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  • 1.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Petrakov, Dmitry A.
    Ivanov, Mikhail N.
    Alexander, Orkhonselenge
    Rudoy, Alexei N.
    Walther, Michael
    Glacial geomorphology of the Altai and Western Sayan Mountains, Central Asia2016In: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 12, no 1, p. 123-136Article in journal (Refereed)
    Abstract [en]

    In this article, we present a map of the glacial geomorphology of the Altai andWestern Sayan Mountains, covering an area of almost 600,000 km2. Although numerous studies provide evidence for restricted Pleistocene glaciations in this area, others have hypothesized the past existence of an extensive ice sheet. To provide a framework for accurate glacial reconstructions of the Altai and Western Sayan Mountains, we present a map at a scale of 1:1,000,000 based on a mapping from 30 m resolution ASTER DEM and 15 m/30 mresolution Landsat ETM+ satellite imagery. Four landform classes have been mapped: marginal moraines, glacial lineations, hummocky terrain, and glacial valleys. Our mapping reveals an abundance of glacial erosional and depositional landforms. The distribution of these glacial landforms indicates that the Altai and Western Sayan Mountains have experienced predominantly alpine-style glaciations, with some small ice caps centred on the higher mountain peaks. Large marginal moraine complexes mark glacial advances in intermontane basins. By tracing the outer limits of present-day glaciers, glacial valleys, and moraines, we estimate that the past glacier coverage have totalled to 65,000 km2 (10.9% of the mapped area), whereas present-day glacier coverage totals only 1300 km2 (0.2% of the mapped area). This demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology in remote mountain areas and for quantifying the past glacier dimensions. The glacial geomorphological map presented here will be used for further detailed reconstructions of the paleoglaciology and paleoclimate of the region.

  • 2.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jon M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Lifton, N. A.
    Heyman, J.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Petrakov, D. A.
    Caffee, M. W.
    Ivanov, M. N.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Rogozhina, I.
    Usubaliev, R.
    Evaluating the timing of former glacier expansions in the Tian Shan: A key step towards robust spatial correlations2016In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 153, p. 78-96Article in journal (Refereed)
    Abstract [en]

    The timing of past glaciation across the Tian Shan provides a proxy for past climate change in this critical area. Correlating glacial stages across the region is difficult but cosmogenic exposure ages have considerable potential. A drawback is the large observed scatter in Be-10 surface exposure data. To quantify the robustness of the dating, we compile, recalculate, and perform statistical analyses on sets of 10Be surface exposure ages from 25 moraines, consisting of 114 new and previously published ages. We assess boulder age scatter by dividing boulder groups into quality classes and rejecting boulder groups of poor quality. This allows us to distinguish and correlate robustly dated glacier limits, resulting in a more conservative chronology than advanced in previous publications. Our analysis shows that only one regional glacial stage can be reliably correlated across the Tian Shan, with glacier expansions occurring between 15 and 281 a during marine oxygen isotope stage (MIS) 2. However, there are examples of older more extensive indicators of glacial stages between MIS 3 and MIS 6. Paleoglacier extent during MIS 2 was mainly restricted to valley glaciation. Local deviations occur: in the central Kyrgyz Tian Shan paleoglaciers were more extensive and we propose that the topographic context explains this pattern. Correlation between glacial stages prior to late MIS 2 is less reliable, because of the low number of samples and/or the poor resolution of the dating. With the current resolution and spatial coverage of robustly-dated glacier limits we advise that paleoclimatic implications for the Tian Shan glacial chronology beyond MIS 2 are speculative and that continued work toward robust glacial chronologies is needed to resolve questions regarding drivers of past glaciation in the Tian Shan and Central Asia.

  • 3.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Caffee, Marc W.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Rogozhina, Irina
    Ivanov, Mikhail N.
    Petrakov, Dmitry A.
    Walther, Michael
    Rudoy, Alexei N.
    Zhang, Wei
    Orkhonselenge, Alexander
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lifton, Nathaniel A.
    Jansson, Krister N.
    Paleoglaciation on opposite flanks of the Ikh-Turgen Mountains, Central Asia: Importance of style of moraine deposition for 10-Be surface exposure datingManuscript (preprint) (Other academic)
    Abstract [en]

    The ages of marginal moraines that record extensive glacier expansions across the Altai Mountains of Central Asia are poorly documented. We present 18 10Be exposure ages from moraines in valleys on opposite flanks of the Ikh-Turgen Mountains. On the eastern side, exposure ages from a latero-frontal moraine indicate deglaciation during MIS 3 (45.3±2.7 ka) and MIS 2 (22.8±3.5 ka). Corresponding exposure ages, from the western side, indicate a more complex story with large scatter (~14-53 ka). Owing to their close proximity, the paleoglaciers should have responded similarly to climate forcing, yet they exhibited a distinctly different behavior. We propose that differences in glacier dynamics caused differences in ice-marginal depositional environments, explaining the scatter in exposure ages on the western side. This study shows the importance of style of deposition in chronological studies of glacial landforms and demonstrates that certain moraine types can be difficult to use as paleoclimate proxies.

  • 4.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Bern, Switzerland.
    Caffee, Marc W.
    Heyman, Jakob
    Rogozhina, Irina
    Ivanov, Mikhail N.
    Petrakov, Dmitry A.
    Walther, Michael
    Rudoy, Alexei N.
    Zhang, Wei
    Orkhonselenge, Alexander
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lifton, Nathaniel A.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Timing and dynamics of glaciation in the Ikh Turgen Mountains, Altai region, High Asia2018In: Quaternary Geochronology, ISSN 1871-1014, E-ISSN 1878-0350, Vol. 47, p. 54-71Article in journal (Refereed)
    Abstract [en]

    Spanning the northern sector of High Asia, the Altai region contains a rich landform record of glaciation. We report the extent, chronologies, and dynamics of two paleoglaciers on opposite flanks of the Ikh Turgen mountains (In Russian: Chikhacheva Range), straddling the border between Russia and Mongolia, using a combination of remote sensing-based glacial geomorphological mapping, Be-10 surface exposure dating, and geomorphometric analysis. On the eastern side (Mongolia), the Turgen-Asgat paleoglacier, with its potential for developing a large accumulation area (similar to 257 km(2)), expanded 40 km down valley, and mean ages from a latero-frontal moraine indicate deglaciation during marine oxygen isotope stage (MIS) 3 (45.1 +/- 1.8 ka, n = 4) and MIS 2 (22.8 +/- 3.3 ka, n = 5). These minimum age constraints are consistent with other Be-10 glacial chronologies and paleoclimate records from the region, which indicates glacier culmination during cold and wet conditions coinciding with MIS 3 (piedmont-style glaciation; inferred for a few sites across the region) and glacier culmination during cold and dry conditions coinciding with MIS 2 (mainly valley-style glaciation; inferred from several sites across the region). On the western side (Russia), the Boguty paleoglacier had a smaller accumulation area (similar to 222 km(2)), and advanced 30 km down valley across a low gradient forefield. Surface exposure ages from two moraine complexes on this side of the mountains exhibit wide scatter (similar to 14-53 ka, n = 8), making paleoclimate inferences and comparison to other proxies difficult. Ice surface profile reconstructions imply that the two paleoglaciers likely shared an ice divide.

  • 5.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Topographic and climatic controls on paleoglaciation patterns across the Tian Shan and Altai Mountains, Central AsiaManuscript (preprint) (Other academic)
    Abstract [en]

    Reconstructing spatial patterns of the extents and dynamics of paleoglaciers across Central Asia is key in understanding the mechanisms of global environmental change. The Tian Shan and Altai Mountains are located in the continental interior of Eurasia, at the confluence of several major climate systems. In order to test hypothesized patterns in paleoglacier extent, and to test the role of paleoclimate and mountain topography in modulating the evolution of these glacial systems, we perform a domain-wide terrain analysis. We first divide the Tian Shan and the Altai Mountains into six physiographic regions delineated by major drainage divides and outlining generalised climate zones. Thereafter we mine published datasets on the distribution of glaciers and glacial landforms, calculate their area-elevation distributions (hypsometry), and extract present-day regional equilibrium line altitudes (ELAs) and long-term average ELAs (paleo-ELAs). We show that the use of glacial landform hypsometry is an effective tool to quantify broad-scale paleoglaciation patterns and find that there is a regional variability in glacier extents across the Tian Shan and Altai Mountains. Reconstructed ELAs show pronounced spatial gradients; increasing ELAs from northern to southern Tian Shan, and increasing ELAs from the northern to both the southeastern and southwestern Altai Mountains. In contrast, maximum paleoglaciation patterns and paleo-ELAs were more uniform across the two mountain systems, with inter-regional topographic variability influencing moraine distributions and thus complicating regional paleo-ELA determinations. Because estimated paleo-ELAs were relatively uniform across the Tian Shan and Altai Mountains, the paleo-ELA lowering were most pronounced in the more continental southern and eastern regions. Our current data is insufficient to explain whether this observation is the result of a different regional paleoclimatic regime than today, or if paleoglaciers responded dynamically different to a paleoclimate forcing of the same magnitude. Our ELA reconstructions also lack temporal constraints, so we furthermore propose that future studies systematically compare hypsometry-derived ELA reconstructions with those stemming from surface energy mass balance models, other proxy records (i.e. lake- and ice core records), and from chronologically constrained ice-marginal moraines.  

  • 6.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hall, Adrian M
    University of St Andrews, Scotland, UK.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pre-glacial landforms on a glaciated shield: the inselberg plains of northern Sweden2012In: Norsk Geologisk Tidsskrift, ISSN 0029-196x, Vol. 92, no 1, p. 1-17Article in journal (Refereed)
    Abstract [en]

    We investigate the long-term geomorphological evolution of the inselberg plains on the glaciated northern Fennoscandian shield. The shield surface has been largely stripped of pre-Quaternary correlative sediments and saprolites by non-glacial and glacial erosion, which makes investigations of pre-Quaternary landscape development a challenge. The relief of the study area, covering 33,000 km3 in the centre of the shield in northern Sweden, includes an abundance of inselbergs that provide the basis for the study. We examine the relief of the inselberg plains, integrated with glacial-geomorphologic features, geology, and weathering remnants, by using GIS-analysis and fieldwork. Several key areas are used to demonstrate the impact of glaciations on the large scale relief, and the influence of geology, structure and deep weathering on relief formation.

    Glacial erosion had only a minor impact on the large-scale bedrock morphology of northern Sweden. Based on excavations and observations in the Parkajoki area, an area largely preserved under cold-based ice during Quaternary glaciations, we infer that grus weathering, resulting in saprolite covers of up to 10-20 m thickness, occurred in the Neogene. However, inselbergs are considerably higher than that, and must therefore be the result of older deep weathering and erosional events. Narrow fracture zones associated with deep kaolins found in northern Fennoscandia may represent the roots of older generations of deep weathering covers but their age and formation is yet unclear.  The geology of the area has greatly influenced the present surface relief. The positions and footprints of the inselbergs are often closely controlled by bedrock type and fracturing. Granite inselbergs generally have dome forms where dome shape and slopes are determined by joint patterns. Steps between palaeosurfaces locally coincide with lithological boundaries and major faults. These links indicate the fundamental importance of etch processes in shaping the relief through multiple cycles of deep weathering and stripping. Palaeosurfaces have been extended and lowered through time, with isolation of small inselbergs during erosion of higher palaeosurfaces. The timescales for relief generation remain uncertain and there is a pressing need to understand the significance of and to date the sediments, saprolites and weathered ore bodies that rest on the surface of the northern Fennoscandian shield.

  • 7.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hall, Adrian M.
    School of GeoSciences, University of Edinburgh, Edinburgh, UK.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Multi-phase development of a glaciated inselberg landscapeManuscript (preprint) (Refereed)
    Abstract [en]

    We investigate the evolution of a glaciated inselberg landscape in northern Sweden since the late Mesozoic, c. 65 million years ago. The study area is part of the Fennoscandian shield and has been stripped of cover rocks and also largely of weathering mantles by preglacial and glacial erosion to leave low relief inselberg plains, with a thin cover of Quaternary deposits. We use these inselbergs as the basis for study of the impact of glacial and preglacial erosion on the shield landscape. GIS-analyses of digital elevation models (DEMs) enable us to identify the morphometry of the inselbergs. Field mapping and mechanical excavations of inselberg margins allow links to be explored between dome-like granite inselbergs and sheet structures and to examine till and saprolite mantles. Very low glacial erosion in the Parkajoki area allows the final stages of preglacial relief development to be reconstructed for the Late Neogene. The hypsometry of the study area, in combination with inselberg elevation and distribution, allows four palaeosurfaces to be identified.

     

    The effects of glacial erosion on the bedrock forms of the inselbergs of the study area were generally restricted to inselberg streamlining by steepening of inselberg flanks. The inselberg landscape relief was enhanced by the removal of saprolite mantles during the Quaternary glaciations. The saprolites formed during the late Neogene, thin or absent close to the inselberg summits and of 10-20 m thickness at the inselberg feet and on the plains. The inselbergs are much older features, however, and deep kaolinization and soft ores are evidence for development by etching from a Mesozoic base level surface. Eocene marine clays on the continuation of the inselberg plains in northern Finland at around 260 m a.s.l. indicate that the inselberg plains above the Pakko palaeosurface generation predate the Paleogene-Eocene thermal maximum. Erosion rates, calculated for two reconstructed summit envelope surfaces, range between 1.5m/Myr and 4.8m/Myr since the late Mesozoic. The inselberg plains of northern Sweden are therefore directly comparable to other shield landscapes in extra-glacial areas that have experienced episodes of deposition of thin cover rocks, long periods of weathering and very low long term rates of erosion.

  • 8.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    The impact of Quaternary glaciations on inselbergs in northern Sweden2010In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 115, no 1-2, p. 56-66Article in journal (Refereed)
    Abstract [en]

    We investigate the glacial modification of inselbergs (large, isolated bedrock hills) in northern Sweden. Inselbergs are generally regarded as products of deep weathering (etching) and stripping under warm and humid climates. Unlike inselbergs found in the tropics, the inselbergs in northern Sweden were exposed to ice sheet glaciation for long periods of the Quaternary. We used DEMs to examine 794 inselbergs in our study area and they were classified according to their degree of glacial modification. Bedrock structural control was assessed using GIS data on the regional geology. Clusters of inselbergs were mapped in the field for features indicative of glacial erosion, such as glacial cliffs and stripped bedrock surfaces, and for features indicative of limited erosion, such as tors and blockfields. The results of the study indicate that inselbergs in the area were mostly modified by Quaternary ice sheets only to a low or moderate extent and that the degree of glacial erosion is dependent on their relief and location. Inselbergs with a relative relief of < 100 m and in areas of lower absolute relief experienced the strongest glacial modification, where the strongest glacial modification can result in lateral erosion of the inselberg flanks. Inselberg summits often display signs of minimal glacial erosion, such as tor-like bedrock outcrops with signs of strong weathering. In summary, we argue that inselbergs in northern Sweden have largely retained their pre-Quaternary shape despite long periods of ice sheet cover.

  • 9.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    DEM-analysis of palaeosurface remnants in the mountain zone of northern SwedenManuscript (preprint) (Refereed)
    Abstract [en]

    Palaeosurface remnants are parts of old planation surfaces that have been elevated and partly down-cut by subsequent erosion. Such surfaces constitute an important landscape element when reconstructing the evolution of a landscape’s tong term development, although their morphological identification may be uncertain. In this study we examine to which degree palaeosurface remnants and surface generations can be identified objectively by GIS-analyses. A combination of fieldwork and GIS-analysis of digital elevation models (DEMs) was used to investigate palaeosurface remnants in two study areas, Ätnajåkki valley and Tjeuralako plateau in the northern Scandes of Sweden.

    Our results indicate that surfaces with an inclination of less than 11 °, and that were not affected by glacial erosion, correspond well with palaeosurface remnants as mapped subjectively in the DEM, air photos and in the field. Peaks in the hypsographic curves, at similar elevation intervals for both areas, show the altitudinal distribution of several palaeosurface generations that were identified in the field.

    The DEM analysis is shown to be a useful tool, but subjective mapping of glacially eroded areas is necessary to exclude glacially eroded areas, some of which may otherwise be misinterpreted as palaeosurface remnants, in the DEM. Hence, the combination of field observations and GIS-analyses is important when mapping and analysing palaeosurface remnants and their distribution correctly in a DEM. The method shown is nonetheless straightforward and reproducible.

  • 10.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hall, Adrian M.
    University of Edinburgh, UK.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    DEM identification of macroscale stepped relief in arctic northern Sweden2011In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 132, no 3-4, p. 339-350Article in journal (Refereed)
    Abstract [en]

    Stepped relief is a characteristic feature of many upland areas on Earth. In this study, we examine if stepped relief can be identified objectively by GIS-analysis of digital elevation models (DEMs). We specifically study the stepped relief landscapes of northern Sweden, comprising areas of contrasting topography in the mountainous northern Scandes and on the inselberg plains of the Precambrian basement east of the Caledonides.We mainly use hypsographic curves to examine the elevation distribution of the study areas and to identify palaeosurfaces. Peaks in the hypsographic curves are interpreted as palaeosurfaces, while hypsographic minima are interpreted as breaks in slope, separating these surfaces. In the northern Scandes, where only patchy remnants of palaeosurfaces remain, we use empirical cutoff values of slope angles to restrict palaeosurface areas to those identified in thefield and in air photos. In addition, air photo andfield mapping of glacially eroded areas is necessary to exclude glacially formed low relief surfaces, such as valley floors. These latter procedures introduce an unavoidable degree of subjectivity to the study. Our results indicate that in the northern Scandes, surfaces with an inclination of 11°, after glacially formed features are abstracted, correspond well with palaeosurface remnants. Breaks in slope separating the surface generations in themountains are centred around 860, 1320, and 1520 masl (above sea level), respectively. On the plains east of the northern Scandes, hypsographic data were filtered to remove inselbergs in order to analyse only the plains. Hypsographic curves of both the filtered and the unfiltered data of the inselberg plains show minima at elevations that correspond to steps separating multiple palaeosurfaces at elevations of 190, 250, and 400 masl. The steps separating the different palaeosurfaces are, in places, aligned with known geological discontinuities, but extensive remnants also transect structure. The presence of stepped relief is consistent with existing models of phased Cenozoic uplift and incision in northern Fennoscandia.

  • 11.
    Ebert, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Willenbring, Jane
    Norton, Kevin P.
    Hall, Adrian
    University of St Andrews, Scotland, UK.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Meteoric Be-10 concentrations from saprolite and till in northern Sweden: Implications for glacial erosion and age2012In: Quaternary Geochronology, ISSN 1871-1014, E-ISSN 1878-0350, Vol. 12, p. 11-22Article in journal (Refereed)
    Abstract [en]

    We examine Be-10 concentration in two pit profiles in the Parkajoki area at similar to 67 degrees N on the northern Fennoscandian shield in northern Sweden. Due to repeated cover by cold-based, non-erosive ice sheets, the area retains many relict non-glacial features, including tors and saprolites. In the examined pit profiles, gruss-type saprolite developed from weathering of intermediate igneous rocks is overlain unconformably by Weichselian till.

    Our results show that Be-10 concentrations found in the till greatly exceed the levels of Be-10 that can have accumulated since deglaciation at similar to 11 ka and are comparable to those reported from Pliocene and Early Pleistocene tills in North America. Old tills with grussified boulders at depth were excavated in the Parkajoki area and correlations with neighbouring parts of Finland indicate a Middle Pleistocene or older age. Evidence from pit excavations and geochemistry shows that the underlying saprolites have been truncated by glacial erosion and that previously weathered material has been incorporated into the till sequence. Hence, Be-10 inventories in the tills are dominated by material recycled from Middle Pleistocene or older soils, near-surface sediments and saprolite, and cannot be used to date the periods of till deposition. The retention of relict Be-10 in the tills nonetheless confirms minimal glacial erosion.

    Concentrations of meteoric Be-10 in the saprolites are lower than any reported saprolite concentrations measured in other settings. Uncertainty in the pre-glaciation Be-10 concentrations in the saprolites makes age determinations difficult. One possibility is that that the saprolite had higher Be-10 concentrations in the past but that saprolite formation ended after glaciation and burial by till and that the Be-10 has substantially decayed. Modelling of the meteoric Be-10 depth profiles in this case suggests that the saprolites in the Parkajoki area were formed at a minimum of 2 Ma. Erosion of the saprolite allows an older age of up to similar to 5 Ma, with up to 250 cm of material removed and incorporated into later tills. A second possibility is that concentrations of meteoric Be-10 in the saprolite were originally lower, with formation of the saprolite in a period or periods of ice- and permafrost-free conditions before 0.8 Ma.

  • 12. Fabel, D.
    et al.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, J.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dahlgren, K.I.T.
    Retreat rate of the northern Fennoscandian Ice Sheet margin2007In: Geophysical Research Abstracts, 2007Conference paper (Refereed)
    Abstract [en]

    The deglaciation chronologies of the northern and north-eastern margins of the Fennoscandian Ice Sheet are relatively poorly constrained. This is because the principal methodological tool to trace and date the deglaciation pattern, the occurrence of deglaciation varves, does not apply in the northernmost regions of Fennoscandia. Moreover, a paucity of radiocarbon dates allows for only a most generalised pattern for the post-Younger Dryas shrinkage of the ice sheet to its final deglaciation configuration in the northern Swedish mountains. We are tracing the deglaciation of the Fennoscandian Ice Sheet from its Younger Dryas terminal moraines in northern Norway and eastern Finland towards the northern Swedish mountains, using cosmogenic nuclide apparent exposure ages of depositional and erosional features related to the former ice sheet margin. Because the ice sheet had initially warm-based conditions close to its margin, the dominant morphology is one of eskers and aligned lineation systems such as crag-and-tails. Abundant meltwater has locally eroded bedrock to considerable depth and deposited fans or deltas perched above current local base levels. Subglacial conditions during final deglaciation close to the mountain range were cold-based, thus inhibiting the formation of eskers and lineation systems. However, there is a ubiquity of meltwater erosional imprints and occasional plucking scars where, locally, pressure-melting conditions were reached. Surface exposure ages from these different geomorphological settings should yield true deglaciation ages provided the following conditions are met, (i) erosion on crags of crag-and-tails, across transverse erosional scarps, and in meltwater channels has exposed bedrock surfaces without a prior exposure history, and (ii) depositional features contain exposed boulders without a prior exposure history. Results show that transverse erosional scarps and erratics yield reliable deglaciation ages, but that bedrock samples from meltwater channels and crag-and-tails and sediment samples from eskers occasionally yield unreliable deglaciation ages due to cosmogenic nuclide inheritance and potential shielding by snow. Apparent deglaciation ages range from _14 ka at the Younger Dryas moraine to _8 ka approximately 500 km to the south in the northern Swedish Mountains. The spread of ages do not deviate from what would be expected for a regular uninterrupted retreat by the ice margin

  • 13.
    Fredin, Ola
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Relict lateral moraines in northern Sweden: evidence for an early mountain centered ice sheet2002In: Sedimentary Geology, ISSN 0037-0738, E-ISSN 1879-0968, Vol. 149, no 1-3, p. 145-156Article in journal (Refereed)
    Abstract [en]

    Glacial geomorphology along the eastern rim of the Scandinavian mountain range includes glacial landforms from the last deglaciation as well as from earlier glacial stages. One of the most prominent landform groups from earlier glacial stages, and the most diagnostic for ice sheet reconstruction, is a set of lateral moraines. In this paper, we describe these lateral moraines within a key area around Kvikkjokk, northern Sweden. Position of these lateral moraines in relation to the last deglaciation patterns indicates that they were formed before the last glacial maximum (LGM). The location and morphology of moraines show that they were deposited by a mountain centred ice sheet with outlet glaciers along major valleys, emanating from the highlands west of the Kvikkjokk area. This ice sheet was likely less than 170-km wide and no more than 600-m thick. Climatologically and glaciologically, we expect the relict lateral moraines to have been deposited before 75 ka BP (marine oxygen isotope stage 4). Their preservation is a consequence of subsequent overriding of nonerosive cold-based ice. Ice-marginal landforms and deposits from mountain centred ice sheet configurations in Fennoscandia are scarce. Therefore, the relict lateral moraines are important tools for reconstructing these elusive early glacial stages, possibly correlated to the ice sheet inception.

  • 14.
    Fu, Ping
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Purdue University.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Zhou, Li Ping
    Peking University.
    Glacial geomorphology and paleoglaciation patterns in Shaluli Shan, the southeastern Tibetan Plateau — Evidence for polythermal ice cap glaciation2013In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 182, p. 66-78Article in journal (Refereed)
    Abstract [en]

    Glacial geomorphological mapping from satellite imagery and field investigations provide the basis for a reconstructionof the extent and style of glaciation of the Shaluli Shan, a mountainous area on the southeastern TibetanPlateau. Our studies provide evidence for multiple glaciations, including the formation of regional ice caps andvalley glaciers. The low-relief topographywithin the Shaluli Shan, the Haizishan Plateau, and Xinlong Plateau displayzonal distributions of glacial landforms that is similar to those imprinted by Northern Hemisphere ice sheetsduring the last glacial cycle, indicating the presence of regional, polythermal ice caps. Abundant alpine glaciallandforms occur on high mountain ranges. The pattern of glaciated valleys centered on high mountain rangesand ice-scoured low relief granite plateaus with distinctive patterns of glacial lineations indicate a strong topographiccontrol on erosional and depositional patterns by glaciers and ice caps. In contrast to the Shaluli Shan,areas farther north and west on the Tibetan Plateau have not yielded similar landform evidence for regionalice capswith complex thermal basal conditions. Such spatial differences across the Tibetan Plateau are the resultof variations in climate and topography that control the extent and style of glaciations and that reinforce the importanceof detailed geomorphological mapping for understanding paleoclimate variations and characteristics offormer glaciations.

  • 15.
    Fu, Ping
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University.
    Heyman, Jakob
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Glacial geomorphology of the Shaluli Shan area, southeastern Tibetan Plateau2012In: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 8, no 1, p. 48-55Article in journal (Refereed)
    Abstract [en]

    We present a glacial geomorphological map covering 1.04 x 10(5) km(2) of the Shaluli Shan (Shan Mountain), southeastern Tibetan Plateau. Using a 90 m digital elevation model from the Shuttle Radar Topography Mission and 15/30 m Landsat Enhanced Thematic Mapper Plus satellite imagery, we have mapped glacial valleys, marginal moraines, hummocky terrain, glacial lineations and ice-scoured terrain. Lineations and scoured areas largely overlap on the low relief granite plateau of the Shaluli Shan and relate to former ice cap glaciation. These landscape features indicate that past ice cap glaciation included basal sliding conditions, and thus warm-based ice. Glacial valleys and marginal moraines are dominant landforms in the high mountain ranges of Shaluli Shan and occur on and fringing the plateau. This glacial geomorphological map forms the basis for paleoglaciological reconstructions of this southeastern Tibetan Plateau region and indicates the former presence of multiple glaciations involving valley glaciers and ice caps. The map is presented at a scale of 1:630,000.

  • 16.
    Fu, Ping
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University, USA.
    Zhou, Liping
    Department of Urban and Environmental Sciences, Peking University, China.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial geomorphology of the Haizi Shan area, SE Tibetan Plateau2009Conference paper (Refereed)
    Abstract [en]

    The Haizi Shan area on the SE Tibetan Plateau is characterized by an elliptical relatively low relief plateau surrounded by steeper fluvial valleys. Glacial deposits and erosive imprints are widely distributed indicating former glacier expansions of varying extents in a presently ice-free area. We have initiated a project on the glacial history of the Haizi Shan area and we here present some initial mapping results. Glacial landforms have been mapped based on remote sensing (SRTM digital elevation model, Landsat ETM+ satellite imagery, and Google Earth) and one short reconnaissance field season. Well-preserved moraines from different stages and distinctive U-shaped glacial valleys are abundant (Fig. 1). In the Daocheng Valley southwest of the Haizi Shan Plateau we have mapped glacial deposits in the form of discontinued moraine ridges at Sangdui village. This line, which might be the maximum Quaternary glacial extent, can be traced for several kilometers along the western side of the valley as dispersed erratic boulders. This implies that during the maximum glaciation, ice from the Haizi Shan Plateau crossed the valley and reached up to the piedmont of the opposite mountain. Smaller in extent than the former, numerous large moraine ridges reach down towards valley floors along the edges of the Haizi Shan Plateau. In several locations these valleys lack cirque heads indicating former outlet glaciers emanating from a Haizi Shan ice cap. We will use TCN and OSL dates of samples collected from numerous ice marginal moraines of the Haizi Shan Plateau to determine a glacial chronology. Hence, using remote sensing, field investigations and numerical dating techniques for the Haizi Shan we aim to advance our knowledge on Quaternary glaciations of the SE Tibetan Plateau.

  • 17. Fu, Ping
    et al.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Heyman, Jakob
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Caffee, Marc W.
    Ice cap erosion patterns from bedrock Be-10 and Al-26, southeastern Tibetan Plateau2019In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 44, no 4, p. 918-932Article in journal (Refereed)
    Abstract [en]

    Quantifying glacial erosion contributes to our understanding of landscape evolution and topographic relief production in high altitude and high latitude areas. Combining in situ Be-10 and Al-26 analysis of bedrock, boulder, and river sand samples, geomorphological mapping, and field investigations, we examine glacial erosion patterns of former ice caps in the Shaluli Shan of the southeastern Tibetan Plateau. The general landform pattern shows a zonal pattern of landscape modification produced by ice caps of up to 4000 km(2) during pre-LGM (Last Glacial Maximum) glaciations, while the dating results and landforms on the plateau surface imply that the LGM ice cap further modified the scoured terrain into different zones. Modeled glacial erosion depth of 0-0.38 m per 100 ka bedrock sample located close to the western margin of the LGM ice cap, indicates limited erosion prior to LGM and Late Glacial moraine deposition. A strong erosion zone exists proximal to the LGM ice cap marginal zone, indicated by modeled glacial erosion depth >2.23 m per 100 ka from bedrock samples. Modeled glacial erosion depths of 0-1.77 m per 100 ka from samples collected along the edge of a central upland, confirm the presence of a zone of intermediate erosion in-between the central upland and the strong erosion zone. Significant nuclide inheritance in river sand samples from basins on the scoured plateau surface also indicate restricted glacial erosion during the last glaciation. Our study, for the first time, shows clear evidence for preservation of glacial landforms formed during previous glaciations under non-erosive ice on the Tibetan Plateau. As patterns of glacial erosion intensity are largely driven by the basal thermal regime, our results confirm earlier inferences from geomorphology for a concentric basal thermal pattern for the Haizishan ice cap during the LGM.

  • 18.
    Fu, Ping
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Purdue University.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, Marc W.
    Purdue University.
    Complex erosion patterns produced by the Haizishan paleo-ice capManuscript (preprint) (Other academic)
    Abstract [en]

    Determining patterns and rates of glacial erosion is important in understanding landscape evolution, topographic relief production, geochemical cycles, climate change, and glacial thermal regimes of paleo glaciers and ice sheets. Combining in situ $^{10}$Be and $^{26}$Al apparent exposure age dating, geomorphological mapping, and field investigations, we examine glacial erosion patterns of the almost 4 000 km$^2$ Haizishan paleo-ice cap on the southeastern Tibetan Plateau. Our results show that ice caps developed several times on the low relief Haizishan Plateau and produced a zonal pattern of landscape modification. In locations where apparent exposure ages on bedrock are consistent with last deglaciation, complete resetting of the cosmogenic exposure age clock indicates that more than 2 m of glacial erosion occurred during the last major glaciation (which in this area correlates with the global Last Glacial Maximum (gLGM)).  However, older apparent exposure ages on bedrock and in saprolites profiles in areas known to have been covered by the paleo ice cap during gLGM indicate inheritance and thus limited or no erosion by the last ice cap in several areas, including the central zone of the paleo ice cap and at the head of an outlet glacier. Similarly, cosmogenic radionuclide depth profiles in saprolites show erosion of $>$2 m in an outlet valley bottom and in the mountains that make up the northern border of the paleo ice cap, while samples from saprolites in areas of otherwise scoured terrain have a large nuclide inheritance indicating limited erosion. As patterns of glacial erosion intensity are largely driven by basal thermal regime, our results are consistent with a hypothesis of complex thermal regimes for the paleo Haizishan ice cap during gLGM that was proposed previously on the basis of landform patterns. Future work, including glaciological modeling, is required to fully understand the implications and mechanisms of the complex thermal regime of this paleo ice cap.

  • 19.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Deciphering a non-glacial/glacial landscape mosaic in the northern Swedish mountains2008In: Geomorphology, Vol. 93, no 3-4, p. 213-232Article in journal (Refereed)
    Abstract [en]

    Relict surfaces contain information on past surface processes and long-term landscape evolution. A detailed investigation of relict non-glacial surfaces in a formerly glaciated mountain landscape of northern Sweden was completed, based on interpretation of colour infrared aerial photographs, analysis in a GIS, and fieldwork. Working backwards from landscape to process, surfaces were classified according to large- and small-scale morphologies that result from the operation of non-glacial processes, the degree of weathering, regolith characteristics, and the style of glacial modification. Surfaces were also compared in the GIS according to elevation, slope angle, and bedrock lithology. The study revealed five types of relict non-glacial surfaces but also two types of extensively weathered glacial surfaces that were transitional to relict non-glacial surfaces, illustrating spatially variable processes and rates of non-glacial and glacial landscape evolution. Rather than being static preglacial remnants, relict non-glacial surfaces are dynamic features that have continued to evolve during the Quaternary. The classification provides hypotheses for landscape evolution that can be field tested through, for example, terrestrial cosmogenic nuclide studies and geochemical analyses of fine matrix materials. The classification may be applicable to relict non-glacial surfaces in other formerly glaciated landscapes

  • 20.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Fredin, Ola
    Derron, M.-H.
    Relict non-glacial surfaces in formerly glaciated landscapes: dynamic landform systems?2007In: Quaternary International, 2007Conference paper (Refereed)
    Abstract [en]

    Relict non-glacial surfaces occur within many formerly glaciated landscapes

    and contain important information on past surface processes and long-term landscape evolution. While cosmogenic dating has confirmed

    the antiquity of relict non-glacial surfaces, the processes that contribute to their evolution and, consequently, the time scales over which they develop remain poorly understood. Of particular importance

    is the possibility that relict non-glacial surfaces may provide geomorphic markers for the reconstruction of preglacial landscapes, which would allow subsequent glacial erosion to be quantified. Furthermore,

    relict non-glacial surfaces may also hold information on preglacial

    and interglacial environmental conditions. An investigation of relict non-glacial surfaces was undertaken through remote sensing, mapping and analysis of surfaces in a GIS, and regolith studies involving

    cosmogenic dating-, grain size-, X-ray diffraction-, and X-ray fluorescence

    analyses. On the basis of these on-going studies, we show that depending on spatial variables such as bedrock lithology, slope, regolith thickness, and the abundance of fine matrix and water some surfaces are denuding very slowly, while others display more rapid denudation. High spatial variability in denudation rates results in changing surface morphologies over time. Rather than being static preglacial

    remnants, relict non-glacial surfaces are dynamic features that have evolved during the Quaternary. While reconstructions of preglacial

    landscapes and subsequent quantifications of glacial erosion from relict non-glacial surfaces remain valid, the Quaternary evolution of these surfaces should also be considered.

  • 21.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Fredin, Ola
    Derron, M.-H.
    Relict non-glacial surfaces in formerly glaciated landscapes: dynamic landform systems?2007In: Geophysical Research Abstracts, 2007Conference paper (Refereed)
    Abstract [en]

    Relict non-glacial surfaces occur within many formerly glaciated landscapes and contain

    important information on past surface processes and long-term landscape evolution

    (Goodfellow, 2007). While cosmogenic dating has confirmed the antiquity of

    relict non-glacial surfaces, the processes that contribute to their evolution and, consequently,

    the time scales over which they develop remain poorly understood. Of particular

    importance is the possibility that relict non-glacial surfaces may provide geomorphic

    markers for the reconstruction of preglacial landscapes, which would allow

    subsequent glacial erosion to be quantified. Furthermore, relict non-glacial surfaces

    may also hold information on preglacial and interglacial environmental conditions.

    An investigation of relict non-glacial surfaces was undertaken through remote sensing,

    mapping and analysis of surfaces in a GIS, and regolith studies involving cosmogenic

    dating-, grain size-, X-ray diffraction-, and X-ray fluorescence analyses. On

    the basis of these on-going studies, we show that depending on spatial variables such

    as bedrock lithology, slope, regolith thickness, and the abundance of fine matrix and

    water some surfaces are denuding very slowly, while others display more rapid denudation.

    High spatial variability in denudation rates results in changing surface morphologies

    over time. Rather than being static preglacial remnants, relict non-glacial

    surfaces are dynamic features that have evolved during the Quaternary. While reconstructions

    of preglacial landscapes and subsequent quantifications of glacial erosion

    from relict non-glacial surfaces remain valid, the Quaternary evolution of these surfaces

    should also be considered.

    Goodfellow B.W., 2007. Relict non-glacial surfaces in formerly glaciated landscapes.

    Earth-Science Reviews, 80(1-2): 47-73.

  • 22.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stanford University, USA.
    Skelton, Alasdair
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Martel, Stephen J.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Controls of tor formation, Cairngorm Mountains, Scotland2014In: Journal Of Geophysical Research: Earth Surface, ISSN 2169-9003, Vol. 119, no 2, p. 225-246Article in journal (Refereed)
    Abstract [en]

    Tors occur in many granitic landscapes and provide opportunities to better understand differential weathering. We assess tor formation in the Cairngorm Mountains, Scotland, by examining correlation of tor location and size with grain size and the spacing of steeply dipping joints. We infer a control on these relationships and explore its potential broader significance for differential weathering and tor formation. We also assess the relationship between the formation of subhorizontal joints in many tors and local topographic shape by evaluating principle surface curvatures from a digital elevation model of the Cairngorms. We then explore the implications of these joints for tor formation. We conclude that the Cairngorm tors have formed in kernels of relatively coarse grained granite. Tor volumes increase with grain size and the spacing of steeply dipping joints. We infer that the steeply dipping joints largely formed during pluton cooling and are more widely spaced in tor kernels because of slower cooling rates. Preferential tor formation in coarser granite with a wider joint spacing that is more easily grusified indicates that joint spacing is a dominant control on differential weathering. Sheet jointing is well developed in tors located on relatively high convex surfaces. This jointing formed after the gross topography of the Cairngorms was established and before tor emergence. The presence of closely spaced (tens of centimeters), subhorizontal sheeting joints in tors indicates that these tors, and similarly sheeted tors elsewhere, formed either after subaerial exposure of bedrock or have progressively emerged from a regolith only a few meters thick. Key Points <list list-type=bulleted id=jgrf20195-list-0001> <list-item id=jgrf20195-li-0001>Tors form in kernels of coarse-grained granite among finer-grained granite <list-item id=jgrf20195-li-0002>Wide joint spacing in tors attributable to a slow cooling rate of the granite <list-item id=jgrf20195-li-0003>Sheet jointing discounts tor formation within a thick regolith

  • 23.
    Hall, Adrian
    et al.
    University of St Andrews, Scotland, UK.
    Ebert, Karin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pre-glacial landform inheritance in a glaciated shield landscape2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 1, p. 33-49Article in journal (Refereed)
    Abstract [en]

    We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre-glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées.

    Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold-based, non-erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large-scale, pre-glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi-quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre-glacial landforms can survive long periods of glaciation, including episodes of wet-based flow.

  • 24.
    Harbor, Jon
    et al.
    Department of Earth and Atmospheric Sciences, Purdue University.
    Fu, Ping
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Zhou, Liping
    Department of Geography, Peking University.
    Glacial Geomorphology of the Haizi Shan area, SE Tibetan Plateau2010Conference paper (Refereed)
    Abstract [en]

    The Haizi Shan area on the SE Tibetan Plateau is characterized by a relatively low relief plateau surrounded by steeper fluvial valleys. Glacial deposits and erosive imprints are widely distributed indicating former glacier expansions of varying extents in a presently ice-free area. Glacial landforms have been mapped using remote sensing (SRTM digital elevation model, Landsat ETM+ satellite imagery, and Google Earth) and field reconnaissance. Well-preserved moraines from different stages and distinctive U-shaped glacial valleys are abundant. In the Daocheng Valley southwest of the Haizi Shan Plateau we have mapped glacial deposits which likely reflect the maximum Quaternary glacial extent for several kilometers along the western side of the valley. During the maximum glaciation, we infer that ice from the Haizi Shan Plateau crossed the valley and extended in to tributary valleys. Numerous large moraine ridges also reach down towards valley floors along the edges of the Haizi Shan Plateau. In several locations these valleys lack cirque heads indicating former outlet glaciers emanating from a Haizi Shan ice cap. In ongoing work we are using TCN and OSL to determine a glacial chronology for this area and advance our knowledge of Quaternary glaciations of the SE Tibetan Plateau.

  • 25.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    A glacial geomorphological map of the northeastern Tibetan plateau2007In: Geophysical Research Abstracts, 2007Conference paper (Refereed)
    Abstract [en]

    The extent and chronology of Quaternary glaciations on the Tibetan plateau are still elusive, and reconstructions range from an ice sheet covering the entire plateau to local valley glaciers restricted to the highest mountain areas. Glacial landforms and deposits constitute the primary data set used for reconstructing the extent of former glaciers. However, this data has rarely been systematically mapped over large areas, making it problematic to evaluate proposed palaeoglaciological reconstructions. Today, detailed maps of the glacial geomorphology, such as those which form the basis for reconstructions of the North American and European ice sheets, only exist for restricted areas on the Tibetan plateau. Hence, in order to evaluate existing palaeoglaciological reconstructions, and to be able to propose alternative reconstructions, regional-scale or plateau-wide scale mapping efforts are required.

    We here present the first detailed map of the glacial geomorphology covering a large area of the northeastern Tibetan plateau, encompassing the location of a previously suggested regional-scale ice sheet – the Huang He ice sheet. The map covers an area of ~135.000 km2, is centered around the Bayan Har Mountains, and is constrained in the southwest by Chang Jiang (Yangtze River). The map is based on an interpretation of satellite images (Landsat ETM+, Landsat TM, ASTER), a digital elevation model (SRTM 90 m resolution) and Google Earth imagery. Field checks of mapped landforms have been performed during two field seasons, 2005 and 2006. Identified glacial landforms are marginal moraines, marginal moraine remnants, glacial hummocky terrain, glacial lineations and glacial meltwater channels.

    There is a clear pattern of numerous glacial landforms distributed in and around higher mountain areas, whereas glacial landforms are absent on surfaces in-between the higher mountain blocks. Upland areas such as the Bayan Har Mountains display a consistent pattern of glacial lineations in the higher central parts of the mountains, series of end moraines across glacially eroded valleys, and glacial hummocky terrain and meltwater channels mainly in the lower slopes of the mountains. The mapped glacial landforms reveal evidence of glacial advances of varying extent in and around several separate mountain areas. The presented map will be used for reconstructing the outline of former glaciation, which, together with chronological constraints from cosmogenic nuclide- and optically stimulated luminescence samples, will eventually form a new paleoglaciological reconstruction for the northeastern Tibetan plateau.

  • 26.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    A glacial geomorphological map of the northeastern Tibetan plateau2007In: Quaternary International, 2007Conference paper (Refereed)
    Abstract [en]

    The extent and chronology of Quaternary glaciations on the Tibetan plateau remains elusive, despite intensified research over the past 20 years. While reconstructions of the North American and European ice sheets are fairly well established, the extent of Tibetan palaeo-glaciers range from an ice sheet covering the entire plateau to local valley glaciers restricted to the highest mountain areas. The primary data for reconstructing the outline of former glaciers are glacial landforms and glacial deposits. However, for the Tibetan plateau this data has rarely been systematically mapped over large areas, making it problematic to evaluate proposed palaeoglaciological reconstructions. In order to make well motivated reconstructions of the extent of palaeo-glaciers based on sound evidence, regional-scale or plateau-wide scale mapping efforts are required. We here present the first detailed glacial geomorphological map of the northeastern Tibetan plateau, covering an area of c. 135.000 km2 centered on the Bayan Har Mountains and encompassing a previously suggested ice sheet – the Huang He ice sheet. The landscape is characterized by a plateau surface at c. 4300 m asl, higher mountain groups reaching up to 1500 m above the plateau surface and marginal areas of fluvial incision by rivers draining the Tibetan plateau creating a steep, fluvial landscape. The map is based on interpretation of satellite images (Landsat ETM+, Landsat TM, ASTER), a digital elevation model (SRTM 90 m resolution) and Google Earth imagery. Field investigations of the mapped landforms have been performed during two field seasons, 2005 and 2006. We have identified and mapped glacial valleys and cirques, marginal moraines, marginal moraine remnants, glacial hummocky terrain, glacial lineations and glacial meltwater channels. Glacial landforms are abundant mainly in and around higher mountain blocks, whereas there is a lack of glacial landforms identifiable by remote sensing in the intervening, lower areas. Upland areas such as the Bayan Har Mountains display a consistent pattern of glacial lineations in the higher central parts of the mountains, marginal moraines across glacially eroded valleys and glacial hummocky terrain and meltwater channels mainly on the lower slopes of the mountains. The mapped landforms indicate glacial advances of varying extent in and around several mountain areas. The presented map, together with chronological constraints from cosmogenic isotope and optically stimulated luminescence dating, will eventually form the basis for a new palaeoglaciological reconstruction for the northeastern Tibetan plateau.

  • 27.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hättestrand, Clas
    Stroeven, Arjen P
    Glacial geomorphology of the Bayan Har sector of the NE Tibetan Plateau2008In: Journal of Maps, ISSN 1744-5647, Vol. 2008, p. 42-62Article in journal (Refereed)
    Abstract [en]

    We here present a detailed glacial geomorphological map covering 136,500 km2 of the Bayan Har sector of the northeastern Tibetan Plateau - an area previously suggested to have nourished the most extensive Quaternary glaciers of the Tibetan Plateau. The map, presented at a scale of 1:650,000, is based on remote sensing of a 90 m SRTM digital elevation model and 15/30 m Landsat ETM+ satellite imagery. Seven landform types have been mapped; glacial valleys, glacial troughs, glacial lineations,marginal moraines, marginal moraine remnants, meltwater channels and hummocky terrain. A large number of glacial landforms exist, concentrated around mountain blocks protruding above the surrounding plateau area, testifying to former glacial activity. In contrast, large plateau areas of lower altitude lack glacial landforms. The mapped glacial geomorphology indicates multiple former glacial advances primarily by valley and piedmont glaciers, but lends no support to the hypothesis of ice sheet scale glaciation in the area. The presented glacial geomorphological map demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology of the Tibetan Plateau, and it will be used for reconstructing the paleoglaciology of the Bayan Har sector of the northeastern Tibetan Plateau.

  • 28.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Caffee, Marc W
    Department of Physics/Purdue Rare Isotope Measurement Laboratory, Purdue University, USA.
    Li, Yingkui
    Department of Geography, University of Missouri-Columbia, USA.
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University, USA.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Zhou, Liping
    Department of Geography, Peking University, China.
    Constraining the glacial chronology of Bayan Har Shan, NE Tibetan Plateau – Cosmogenic exposure dating of boulders, surface pebbles/cobbles and sediment depth profiles2009In: Geophysical Research Abstracts: Vol. 11, EGU2009-12053, 2009, 2009Conference paper (Refereed)
    Abstract [en]

    The paleoglaciology of the Tibetan Plateau remains elusive, with important hiata regarding the style, extent, and timing of glaciations. Bayan Har Shan is a mountain region on the northeastern Tibetan Plateau, in a transition zone from the dry interior of the plateau in the west to the wetter eastern margin affected by the Asian monsoon. Bayan Har Shan hosts an ample record of glacial landforms and deposits indicating paleo-glaciers ranging from cirque and valley glaciers to ice-fields and ice caps. These glaciers, it has been suggested, also nourished a regional ice sheet. In an attempt to constrain the timing of glaciations in Bayan Har Shan, we have performed terrestrial cosmogenic nuclide (TCN) exposure dating on surface boulders and pebbles/cobbles from glacial deposits, and on pebbles in sediment depth profiles. The aim has been two-fold: to constrain the glacial chronology and to compare and evaluate the TCN ages of the three different TCN sample types.

    We present the result of 67 Be-10 measurements from 15 sites in central Bayan Har Shan (40 boulder samples, 12 surface pebbles/cobbles samples and 15 depth profile samples from four depth profiles). The obtained TCN apparent exposure ages of boulders and surface pebbles/cobbles range from 3 ka to 145 ka with wide age spreads within groups of samples collected from one glacial deposit. Our TCN results of three different sample types (boulders, surface pebbles/cobbles and depth profile pebbles) from the northeastern Tibetan Plateau form an intriguing data set that may yield different age estimates with different interpretation strategies. However, they permit the following conclusions to be advanced:

    • Pebbles/cobbles ages are broadly in agreement with boulder ages.

    • Three depth profiles yield exponential curves for Be-10 concentrations with depth, in agreement with theoretical TCN depth profiles; ages are in broad agreement with boulder and surface pebbles/cobbles samples.

    • Maximum ages (adopting an approach where the maximum ages constrain the minimum age of formation) of multiple sample sites are all c. 50 ka or older. This is underlined by the maximum ages around 50 ka from three moraines formed by glaciers just a few kilometres long, indicating that there has been no significant glaciation of central Bayan Har Shan over the last 50 ka.

  • 29.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Li, Yingkui
    Harbor, Jon
    Caffee, Marc
    Zhou, Liping
    Veres, Daniel
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial landforms and deposits of the Bayan Har Shan, NE Tibetan plateau – a dataset for reconstructing the extent of former glaciations2008Conference paper (Refereed)
    Abstract [en]

    Glacial reconstructions of the Tibetan plateau range from a plateau-scale ice sheet to restricted valley glaciers and ice caps. However, the Tibetan glacial landforms and sediments – although forming a crucial tool for paleoglaciological reconstructions – have rarely been mapped for larger areas. We here present data on the glacial landforms and deposits in the Bayan Har Shan area on the northeastern Tibetan plateau, previously suggested to have nourished the most extensive Quaternary Tibetan ice mass. Detailed geomorphological mapping based on remote sensing and extensive field studies reveal a generous array of glacial landforms and deposits, indicating former glaciers of varying extent. Large scale glacial landforms mapped from a digital elevation model and satellite imagery are abundant in elevated mountain blocks. The mapped landforms testify of alpine style glaciation but lend no support to the existence of any ice sheet. Field observations of glacial, and non-glacial, deposits further enhance the dataset concerning former glacial extent. Tills and erratic boulders are present within the glacial landscape based on remote sensing, but in several localities they also exist further down some distance outside mapped glacial landforms. There is a notable absence of glacial deposits around the Huang He valley and in the northern part of the study area, where they have previously been reported as evidence of a paleo-ice sheet. We argue for a non-glacial origin of deposits in these areas, because we have not found any indications of a glacial origin. The mapped landforms and deposits display an interesting dataset for paleoglaciological reconstructions. While the glacial landforms from remote sensing – by virtue of completeness covering extensive areas – present a good image of the more restricted glaciations, the identified most extensive glaciation is so far only recorded as point data in the form of glacial deposits.

  • 30.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Li, Yingkui
    Harbor, Jon
    Caffee, Marc
    Zhou, Liping
    Veres, Daniel
    Reconstructing former glacial extent of the NE Tibetan Plateau – combining remote sensing and field data of glacial geology2008In: Geophysical Research Abstracts, 2008Conference paper (Refereed)
    Abstract [en]

    Glacial reconstructions of the Tibetan Plateau range from a plateau-scale ice sheet to restricted valley glaciers and ice caps. However, glacial landforms and sediments – although forming a crucial fundament for paleoglaciological reconstructions – have rarely been mapped for extensive areas of the Tibetan Plateau. The NE Tibetan Plateau hosts a wide array of glacial landforms and deposits, and the area has been suggested to have nourished an extensive Quaternary ice mass on the Tibetan Plateau – the Huang He ice sheet. We here present data on the glacial geology of the Bayan Har Shan area, NE Tibetan Plateau, based on two diverse methods: remote sensing and field observations. Using the SRTM 90 m resolution digital elevation model, Landsat ETM+ satellite images and Google EarthTM imagery, a detailed mapping of the glacial geomorphology for a 135.000 km2 area has been performed. Mapped landforms include glacial valleys/troughs, marginal moraines, glacial lineations, meltwater channels and hummocky terrain. During 2005-2007 field work we have gathered data on glacial and non-glacial deposits. Deposits affirmative of glacial action occur in the form of till, glaciofluvial sediments and erratic boulders. Using a simple identification scheme, based on the abundance of erratic boulders, striated clasts and presence of diamictic sediments, we have mapped the occurrence of glacial deposits.

    The remote sensing and field data in general strongly support the presence of former glaciers centred on mountain blocks, and offers no support for the former existence of an ice sheet. However, there is a discrepancy between the glacial geomorphology mapped by remote sensing and the distribution of glacial deposits as mapped in the field. Glacial landforms mapped by remote sensing indicate former glaciers of varying extent, ranging from cirque glaciers to extended valley glacier networks, with glacial U-shaped valleys up to 60 km long. Whereas glacial deposits occur most frequently in the areas of mapped glacial landforms, they also occur up to 25 km outside mapped glacial landforms and indicate ice cap/ice field glaciation, presumably predating more restricted glaciations marked by marginal moraines and meltwater channels. The presence of glacial deposits in the absence of glacial morphology has implications for the large-scale glacial imprint, as glacial landforms of the most extensive glaciation(s) have either been eroded/degraded, or been buried by subsequent deposits, or else were never been formed. On the basis of an absence of erosional morphology, we conclude that erosion by such an enlarged ice cap/ice field beyond the mountains has been negligible.

  • 31.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Zhou, Liping
    Dong, Jianyi
    Li, Yinkui
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, Marc
    Ma, Haizhou
    Liu, Gengnian
    Landscape evolution of the northeastern Tibetan plateau - relict surfaces and fluvial margins2007In: Geophysical Research Abstracts, 2007Conference paper (Refereed)
    Abstract [en]

    The actively uplifting Tibetan plateau has a profound impact on climate and displays a landscape marked by geomorphological action. This is because the uplift is counteracted by intense fluvial incision of some of the world’s largest rivers and their tributaries that drain the plateau. Glaciers and glacial landforms occur predominantly in and around the highest elevation areas. By investigating the imprints of glacial and fluvial erosion we can enhance our understanding of the long-term landscape evolution, as well as illuminate the paleoglaciology of the Tibetan plateau. We here present an investigation of the large-scale geomorphology of the northeastern Tibetan plateau and its implication for landscape evolution and paleoenvironmental reconstructions.

    The northeastern part of the Tibetan plateau is characterized by a plateau surface at c. 4300 m asl with higher mountain groups reaching up to 1500 m above the surrounding plateau surface. We used SRTM 90 m digital elevation model, satellite images and Google Earth imagery to map the large-scale geomorphology for an area of c. 135.000 km2 centered around the Bayan Har mountains. Our mapping reveals a clear pattern of substantial glacial erosion on the highest, central parts of the mountain areas and decreasing amounts of glacial erosion with decreasing elevation and increasing distance away from these centers of glaciation. Beyond the areas of glacial erosion, there is a low-relief fluvial landscape that typifies the rest of the plateau surface. The plateau margins are formed by steep fluvial valleys which cut backwards into the gentle sloping relict plateau surface. Thus, the overall landscape may be divided into three classes; (i) glacially eroded surfaces in the highest areas, (ii) a relict, low-relief plateau surface, and (iii) a steep, fluvial landscape juxtaposing the former two classes.

    The distribution of the different landscapes indicates the following temporal evolution of the landscape. The glacial landforms indicate a repeated glaciation of the mountain areas. The steep fluvial valleys consuming the relict plateau surface represent an ongoing adjustment of the river channels to the actively uplifting plateau margin. The pattern of abandoned fluvial erosion of the northern part of the study area supports the notion of a stepwise uplift. This is because progressively younger uplift of the northern parts of the area induced a piracy of originally N-flowing rivers to currently ESE-flowing rivers along major faults (such as we infer for the Huang He river). It is noteworthy that the outline of the relict landscape, that is the pronounced break in slope between the low-relief relict landscape and the young fluvial landscape, coincides almost completely with the outline of a hypothesized former ice sheet, the Huang He ice sheet. We have not been able to confirm the presence of geomorphology or stratigraphy that would support this reconstruction. If true, however, our notion of outline conformance could indicate that the Huang He ice sheet may actually have been larger than suggested and that glacial traces are being consumed by the fluvial incision triggered by plateau uplift.

  • 32.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University, USA.
    Li, Yingkui
    Department of Geography, University of Tennessee, USA.
    Caffee, Marc W
    Department of Physics, Purdue Rare Isotope Measurement Laboratory, Purdue University, USA.
    Zhou, Liping
    Department of Geography, Peking University, China.
    Veres, Daniel
    'Emil Racovita' Institute of Speleology, Romania.
    Liu, Feng
    Department of Geography, Peking University, China.
    Machiedo, Martin
    Department of Geology, University Centre in Svalbard (UNIS), Norway.
    Palaeoglaciation of Bayan Har Shan, northeastern Tibetan Plateau: glacial geology indicates maximum extents limited to ice cap and ice field scales2009In: Journal of Quaternary Science, ISSN 0267-8179, E-ISSN 1099-1417, Vol. 24, no 7, p. 710-727Article in journal (Refereed)
    Abstract [en]

    Key locations within an extensive area of the northeastern Tibetan Plateau, centred on Bayan Har Shan, have been mapped to distinguish glacial from non-glacial deposits. Prior work suggests palaeo-glaciers ranging from valley glaciers and local ice caps in the highest mountains to a regional or even plateau-scale ice sheet. New field data show that glacial deposits are abundant in high mountain areas in association with large-scale glacial landforms. In addition, glacial deposits are present in several locations outside areas with distinct glacial erosional landforms, indicating that the most extensive palaeo-glaciers had little geomorphological impact on the landscape towards their margins. The glacial geological record does indicate extensive maximum glaciation, with local ice caps covering entire elevated mountain areas. However, absence of glacial traces in intervening lower-lying plateau areas suggests that local ice caps did not merge to form a regional ice sheet on the northeastern Tibetan Plateau around Bayan Har Shan. No evidence exists for past ice sheet glaciation.

  • 33.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, Marc W.
    Hattestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jonathan M.
    Li, Yingkui
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Zhou, Liping
    Hubbard, Alun
    Palaeoglaciology of Bayan Har Shan, NE Tibetan Plateau: exposure ages reveal a missing LGM expansion2011In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 30, no 15-16, p. 1988-2001Article in journal (Refereed)
    Abstract [en]

    The Bayan Har Shan, a prominent upland area in the northeastern sector of the Tibetan Plateau, hosts an extensive glacial geological record. To reconstruct its palaeoglaciology we have determined (10)Be exposure ages based on 67 samples from boulders, surface pebbles, and sediment sections in conjunction with studies of the glacial geology (remote sensing and field studies) and numerical glacier modelling. Exposure ages from moraines and glacial sediments in Bayan Har Shan range from 3 ka to 129 ka, with a large disparity in exposure ages for individual sites and within the recognised four morphostratigraphical groups. The exposure age disparity cannot be explained by differences in inheritance without using unrealistic assumptions but it can be explained by differences in post-depositional shielding which produces exposure ages younger than the deglaciation age. We present a palaeoglaciological time-slice reconstruction in which the most restricted glaciation, with glaciers less than 10 km long, occurred before 40-65 ka. More extensive glaciations occurred before 60-100 ka and 95-165 ka. Maximum glaciation is poorly constrained but probably even older. The Bayan Hat Shan exposure age dataset indicates that glaciers on the northeastern Tibetan Plateau have remained surprisingly restricted for at least 40 ka, including the global last glacial maximum (LGM). This case of a missing LGM is further supported by high-resolution glacier modelling experiments.

  • 34.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Caffee, Marc W
    Department of Physics, Purdue Rare Isotope Measurement Laboratory, Purdue University.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University.
    Li, Yingkui
    Department of Geography, University of Tennessee, Knoxville.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Zhou, Liping
    Department of Geography, Peking University.
    Hubbard, Alun
    Institute of Geography and Earth Sciences, Aberystwyth University.
    Palaeoglaciology of Bayan Har Shan, NE Tibetan Plateau: the case of a missing LGM expansionManuscript (preprint) (Other academic)
    Abstract [en]

    The Bayan Har Shan, a prominent upland area in the northeastern sector of the Tibetan Plateau, hosts an extensive glacial geological record. To reconstruct its palaeoglaciology we have determined 10Be apparent exposure ages based on 67 samples from boulders, surface pebbles, and sediment sections in conjunction with studies of the glacial geology (remote sensing and field studies) and numerical glacier modelling. Apparent exposure ages from moraines and glacial sediments in Bayan Har Shan range from 3 ka to 129 ka, with a large disparity in ages for individual sites and within the recognised four morphostratigraphical groups. The age disparity is inexplicable as arising from differences in inheritance without the application of unrealistic assumptions but it can be explained as arising from differences in post-glacial shielding, yielding exposure ages younger than the deglaciation age. We present a palaeoglaciological time-slice reconstruction in which the most restricted glaciation, with glaciers less than 10 km long, occurred before 40-65 ka. More extensive glaciations occurred before 60-100 ka and 95-165 ka. Maximum glaciation is poorly constrained but probably even older. The Bayan Har Shan exposure age dataset indicates that glaciers on the northeastern Tibetan Plateau have remained surprisingly restricted for at least 40 ka, including the global last glacial maximum (LGM). This case of a missing LGM is supported by high-resolution glacier modelling experiments.

  • 35.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, Marc W
    Department of Physics/Purdue Rare Isotope Measurement Laboratory, Purdue University, USA.
    Li, Yingkui
    Department of Geography, University of Tennessee, USA.
    Zhou, Liping
    Department of Urban and Environmental Sciences, Peking University, China.
    Liu, Gengnian
    Department of Urban and Environmental Sciences, Peking University, China.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fu, Ping
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University, USA.
    An evaluation of multiple working hypotheses to explain cosmogenic exposure age data from glacial deposits in the Bayan Har Shan, NE Tibetan Plateau2009In: Proceedings, 2009Conference paper (Refereed)
    Abstract [en]

    Many questions remain unanswered regarding the Quaternary glaciations of the Tibetan Plateau. We have used terrestrial cosmogenic nuclide (TCN) exposure age dating of glacial deposits to examine the style, extent, and timing of past glaciations of the Bayan Har Shan, a mountain region on the northeastern Tibetan Plateau. This area lies within a transition zone between the dry interior of the Tibetan Plateau and the wetter eastern margin affected by the Asian monsoon. Bayan Har Shan has many glacial landforms and deposits that provide evidence for former glaciation ranging from cirque and valley glaciers to ice-fields and ice caps.

    In an attempt to constrain the timing of glaciations in Bayan Har Shan, we have performed TCN exposure dating on 65 samples in central Bayan Har Shan from glacial deposits. boulders (39 samples), on surface pebbles/cobbles (12 samples), and on pebbles in sediment depth profiles (14 samples from four profiles) allow us to examine the timing and extent of glaciations in this area. As is often the case, there are some challenges in interpreting the range of TCN apparent exposure ages that is found in data from several samples and sample types on a single deposit and from samples taken at various sites. Thus we evaluate multiple working hypotheses to explain apparent exposure ages on glacial deposits, which in this case range from 3 ka to 129 ka. We consider three different hypotheses; 1) some samples have erroneously old exposure ages due to inheritance, 2) samples have been preserved under cold-based, non-erosive ice, and 3) samples have experienced only post-glacial shielding. Only when we adopt a hypothesis that assumes no prior exposure, and thus that maximum apparent exposure ages constrain the minimum age of formation of a feature (working hypotheses 3), do we find broad consistency between apparent exposure ages from different sample types (erratic boulders, surface pebbles/cobbles and pebbles from depth profiles). This leads to the conclusion that all of the sites of former glaciations we examined are at least 50ka in age, and that there has been no large-scale expansion of glaciers in the central Bayan Har Shan over the last 50ka.

  • 36.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Caffee, Marc W
    Department of Physics, PRIME Lab, Purdue University.
    Fu, Ping
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Harbor, Jon
    Department of Earth And Atmospheric Sciences, Purdue University.
    Hubbard, Alun
    Institute of Geography and Earth Sciences, Aberystwyth University.
    Li, Yingkui
    Department of Geography, University of Tennessee.
    Zhou, Liping
    Department of Geography, Peking University.
    LGM Tibetan Plateau glaciers were not much larger than today2010In: Geophysical Research Abstracts, 2010Conference paper (Refereed)
    Abstract [en]

    The Tibetan Plateau is the largest and highest elevated area on Earth with consequential impacts on regional (monsoon development) and global (CO2 sequestering) climate patterns and evolution, and with its glaciers providing meltwater for some of the largest rivers of the world. The glacial history of the Tibetan Plateau is dominantly characterized by glaciers and ice caps centered on elevated mountain regions of the plateau, as evidenced by an extensive glacial geological record. Here we present the outcome of a five year project aiming towards a palaeoglaciological reconstruction for the Bayan Har Shan region of the northeastern Tibetan Plateau. We have used remote sensing, field studies and 10Be exposure ages towards a robust reconstruction of former glaciation. Glacial landforms and sediments in Bayan Har Shan, distributed around elevated mountain areas, indicate a maximum Quaternary glaciation significantly larger than today. We have dated 40 boulders, 12 surface pebbles samples, and 15 depth profile samples (in 4 depth profiles) from 15 sites (mainly moraine ridges) using 10Be exposure dating. Our boulder and pebble exposure ages range from 3 ka to 128 ka with large age spreads within populations of individual sites. Based on the premise that cosmogenic age spreads within populations are caused by post-depositional shielding which yields exposure ages younger than deglaciation ages (see Heyman et al. Abstract/Poster in session CL4.7/GM2.4/SSP2.5/SSP3.9: EGU2010-14159-1) and based on the exposure ages of the multiple sample types, all dated glacial deposits pre-date the global Last Glacial Maximum (LGM). Our results further indicate that even the innermost and highest of the dated moraines, formed by glaciers <10 km long, have minimum deglaciation ages of 45 ka. These results agree well with those sites on the Tibetan Plateau where samples close outside present-day glacier margins have yielded exposure ages significantly older than the LGM. In fact, for sites where exposure age studies have been performed on the Tibetan Plateau, it is a rule rather than an exception with pre-LGM exposure ages close outside present-day glacier margins. This indicates that during the LGM, when large ice sheets covered North America and northern Europe, glaciers on the northeastern Tibetan Plateau, and perhaps the plateau at large, did not grow much larger than today.

    To explore the climate implications of restricted Tibetan Plateau LGM glaciers, we employ a high-resolution 3D glacier model forced with static climate perturbations of the present-day climate (WorldClim data:http://www.worldclim.org/). Allowing glaciers to grow and expand to but not exceed well-dated moraines enables us to derive and present climate constraints for the Tibetan Plateau during the LGM.

  • 37.
    Heyman, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Department of Earth and Atmospheric Sciences, Purdue University, USA.
    Caffee, Marc W
    Department of Physics/Purdue Rare Isotope Measurement Laboratory, Purdue University, USA.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Li, Yingkui
    Department of Geography, University of Tennessee, USA.
    Zhou, Liping
    Department of Urban and Environmental Sciences, Peking University, China.
    Liu, Gengnian
    Department of Urban and Environmental Sciences, Peking University, China.
    Fu, Ping
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    A paleoglaciological reconstruction for Bayan Har Shan, NE Tibetan Plateau2009Conference paper (Refereed)
    Abstract [en]

    The paleoglaciology of the Tibetan Plateau has remained elusive because extensive areas still lack detailed scrutiny. We here present a paleoglaciological reconstruction for the Bayan Har Shan region, NE Tibetan Plateau, which could serve as a working model to investigate other poorly investigated regions. The reconstruction is primarily based on three methods for revealing the glacial history; 1) remote sensing (geomorphology), 2) field studies (stratigraphy), and 3) numerical dating techniques. Remote sensing (SRTM elevation data, Landsat ETM+ satellite imagery and Google Earth) of a 136 500 km2 area reveals an abundance of glacial landforms in the highest mountain areas and an absence of glacial landforms on intervening plateau surfaces. Stratigraphical data collected during three field seasons supplement the picture emerging from remote sensing. Glacial deposits (including erratic boulders and till) occur in the elevated mountain areas but are absent on the intervening plateau areas. Marginal moraines in central Bayan Har can be grouped to represent at least three separate glacial extents and scattered observations of glacial deposits indicate the presence of a fourth (and maximum) glacial extent. To tie the glacial geological record to a chronology we have employed terrestrial cosmogenic nuclide (TCN) exposure and optically stimulated luminescence (OSL) dating. Beryllium apparent exposure ages of 65 glacial boulders, surface cobbles/pebbles and depth profile samples yield minimum ages for the three youngest glacial extents of 40-65 ka, 60-100 ka, and 95-165 ka (with the wide age ranges due to TCN dating uncertainties). A preliminary OSL age of c. 160 ka from glacial sediments of the oldest of these glacial extents supports our interpretation based on TCN dating.

    The glacial extent presented here is more restricted than most previous reconstructions, most notably with very restricted glaciers over at least the last 40-65 ka. These results indicate that while continental-scale ice sheets evolved and disappeared in North America and Eurasia over the last half of the last glacial cycle, the NE corner of the Tibetan Plateau experienced relatively minor glacial fluctuations.

  • 38. Hillier, J. K.
    et al.
    Smith, M. J.
    Armugam, R.
    Barr, I.
    Boston, C. M.
    Clark, C. D.
    Ely, J.
    Fankl, A.
    Greenwood, Sarah L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Gosselin, L.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hogan, K.
    Hughes, A. L. C.
    Livingstone, S. J.
    Lovell, H.
    McHenry, M.
    Munoz, Y.
    Pellicer, X. M.
    Pellitero, R.
    Robb, C.
    Roberson, S.
    Ruther, D.
    Spagnolo, M.
    Standell, M.
    Stokes, C. R.
    Storrar, R.
    Tate, N. J.
    Wooldridge, K.
    Manual mapping of drumlins in synthetic landscapes to assess operator effectiveness2015In: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 11, no 5, p. 719-729Article in journal (Refereed)
    Abstract [en]

    Mapped topographic features are important for understanding processes that sculpt the Earth's surface. This paper presents maps that are the primary product of an exercise that brought together 27 researchers with an interest in landform mapping wherein the efficacy and causes of variation in mapping were tested using novel synthetic DEMs containing drumlins. The variation between interpreters (e.g. mapping philosophy, experience) and across the study region (e.g. woodland prevalence) opens these factors up to assessment. A priori known answers in the synthetics increase the number and strength of conclusions that may be drawn with respect to a traditional comparative study. Initial results suggest that overall detection rates are relatively low (34-40%), but reliability of mapping is higher (72-86%). The maps form a reference dataset.

  • 39.
    Hättestrand, Clas
    Stockholm University.
    Ribbed moraines and Fennoscandian palaeoglaciology1997Doctoral thesis, comprehensive summary (Other academic)
  • 40.
    Hättestrand, Clas
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Koilka, Vasili
    Johansen, Nina
    Cirque infills in the Khibiny mountains, Kola Peninsula, Russia - palaeoglaciological interpretations and modern analogues in East Antarctica2008In: JOURNAL OF QUATERNARY SCIENCE, ISSN 0267-8179, Vol. 23, no 2, p. 165-174Article in journal (Refereed)
    Abstract [sv]

    We report here on cirque infills mapped in the Khibiny Mountains, Kola Peninsula, Russia. Cirque infills are morainic deposits located near the headwalls of valleys and cirques. Their location and shape, often with concave margins towards the valley side, indicate that they were deposited by ice flowing up-valley, into the mountains, rather than by local glaciers. We suggest that they formed during the last deglaciation, when Khibiny was a nunatak and Fennoscandian ice sheet lobes extended into valleys and cirques of the massif. The formation of cirque infills is probably more related to ice sheet dynamic factors, occurring when the ice margin retreated from the cirques, than to climate-driven interruption in the ice-marginal retreat. Glacial conditions similar to those prevalent when the Khibiny cirque infills were formed, occur today in Antarctica where the ice sheets engulf nunatak ranges. In Heimefrontfjella, Antarctica, the formation of supraglacial moraines at the head of cirques are linked to blue-ice conditions, indicating locally low accumulation rates, a dry continental climate and sublimation dominated ablation. We suggest that these Antarctic moraines are modern analogues of cirque infills on the Kola Peninsula, and possibly, that the cirque infills may be used as palaeoenvironmental indicators.

  • 41.
    Hättestrand, Clas
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kolka, Vasili
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    The Keiva ice marginal zone on the Kola Peninsula, northwest Russia: a key component for reconstructing the palaeoglaciology of the northeastern Fennoscandian Ice Sheet2007In: Boreas, Vol. 36, p. 352-370Article in journal (Refereed)
    Abstract [en]

    One of the key elements in reconstructing the palaeoglaciology of the northeastern sector of the Fennoscandian Ice Sheet is the Keiva ice marginal zone (KIZ) along the southern and eastern coast of Kola Peninsula, including the Keiva I and II moraines. From detailed geomorphological mapping of the KIZ, primarily using aerial photographs and satellite images, combined with fieldwork, we observed the following. (1) The moraines display ice contact features on both the Kola side and the White Sea side along its entire length. (2) The Keiva II moraine is sloping along its length from c. 100 m a.s.l. in the west (Varzuga River) to c. 250 m a.s.l. in the east (Ponoy River). (3) The KIZ was partly overrun and fragmented by erosive White Sea-based ice after formation. From these observations we conclude that the KIZ is not a synchronous feature formed along the lateral side of a White Sea-based ice lobe. If it was, the moraines should have a reversed slope. Rather, we interpret it to be time transgressive, formed at a northeastward-migrating junction between a warm-based Fennoscandian Ice Sheet expanding from the west and southwest into the White Sea depression, and a sluggish cold-based ice mass centred over eastern Kola Peninsula. In contrast to earlier reconstructions, we find it unlikely that an ice expansion of this magnitude was a mere re-advance during the deglaciation. Instead, we propose that the KIZ was formed during a major expansion of a Fennoscandian Ice Sheet at a time pre-dating the Last Glacial Maximum.

  • 42.
    Hättestrand, Clas
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Kolka, V.V.
    The Keiva ice marginal zone on the Kola Peninsula, NW Russia – a complex marginal deposit of the Fennoscandian ice sheet2007In: Quaternary International, 2007Conference paper (Refereed)
    Abstract [en]

    One of the key elements in reconstructing the palaeoglaciology of the northeastern sector of the Fennoscandian Ice Sheet is the Keiva ice marginal zone (KIZ) along the southern and eastern coasts of Kola Peninsula, including the Keiva I and II moraines. From detailed geomorphological

    mapping of the KIZ, primarily using aerial photographs and satellite images, combined with field work, we observe the following:

    (a) The moraines display ice contact features on both the Kola Peninsula- and the White Sea side along its entire length; (b) the Keiva II moraine is sloping along its 220 km length from c. 100 m a.s.l. in the west (Varzuga River) to c. 250 m a.s.l. in the east (Ponoy River); (c) the KIZ was partly overrun and fragmented by erosive White Sea based ice after formation. From these observations we conclude that the KIZ is not a synchronous feature formed along the lateral side of a White Sea based ice lobe. If it was, the moraines should have a reversed slope. Rather, we interpret it to be formed time transgressively at the northeastward

    migrating junction between warm-based parts of the Fennoscandian

    ice sheet expanding from the southwest into the White Sea depression and across southeastern Kola Peninsula, and a sluggish cold-based ice mass centred over eastern Kola Peninsula. In contrast to earlier reconstructions, we find it unlikely that an ice expansion of this magnitude was a mere readvance during the deglaciation. Instead, we propose that the Keiva ice marginal zone was formed during major expansion of a Fennoscandian Ice Sheet at a time predating the LGM. Our geomorphological interpretation is consistent with new Be-10 cosmogenic isotope data of several boulders embedded in the eastern part of the Keiva II moraine, with apparent exposure ages between 250 and 420 ka. One interpretation of the data is that these boulders were deposited as an integral part of the moraine ridge, hence indicating that the KIZ, or at least sections of it, is of Middle Pleistocene age. Another interpretation is that the KIZ is younger than 250 ka (but older than LGM on the strength of the evidence of post-depositional overriding) and that all boulders sampled have considerable inheritance from previous

    exposure periods. The results are also consistent with the geomorphological

    observations indicating that the KIZ has a history far more intricate than has previously been acknowledged in most paleoglaciological

    reconstructions.

  • 43.
    Jansen, John D.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. University of Wollongong, Australia.
    Codilean, A. T.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, D.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kubik, P. W.
    Xu, S.
    Inner gorges cut by subglacial meltwater during Fennoscandian ice sheet decay2014In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, p. 3815-Article in journal (Refereed)
    Abstract [en]

    The century-long debate over the origins of inner gorges that were repeatedly covered by Quaternary glaciers hinges upon whether the gorges are fluvial forms eroded by subaerial rivers, or subglacial forms cut beneath ice. Here we apply cosmogenic nuclide exposure dating to seven inner gorges along similar to 500 km of the former Fennoscandian ice sheet margin in combination with a new deglaciation map. We show that the timing of exposure matches the advent of ice-free conditions, strongly suggesting that gorges were cut by channelized subglacial meltwater while simultaneously being shielded from cosmic rays by overlying ice. Given the exceptional hydraulic efficiency required for meltwater channels to erode bedrock and evacuate debris, we deduce that inner gorges are the product of ice sheets undergoing intense surface melting. The lack of postglacial river erosion in our seven gorges implicates subglacial meltwater as a key driver of valley deepening on the Baltic Shield over multiple glacial cycles.

  • 44.
    Kleman, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    de Angelis, Hernán
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Alm, Göran
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glasser, Neil
    Aberystwyth University.
    North American Ice Sheet build-up during the last glacial cycle, 115-21 kyr2010In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 29, no 17-18, p. 2036-2051Article in journal (Refereed)
    Abstract [en]

    The last glacial maximum (LGM) outline and subsequent retreat pattern (21e7 kyr) of North Americanice sheets are reasonably well established. However, the evolution of the ice sheets during their build-upphase towards the LGM between 115 and 21 kyr has remained elusive, making it difficult to verifynumerical ice sheet models for this important time interval. In this paper we outline the pre-LGM icesheet evolution of the Laurentide and Cordilleran ice sheets by using glacial geological and geomorphologicalrecords to make a first-order reconstruction of ice sheet extent and flow pattern. We mappedthe entire area covered by the Laurentide and Cordilleran ice sheets in Landsat MSS images andapproximately 40% of this area in higher resolution Landsat ETMþ images. Mapping in aerial photographsadded further detail primarily in Quebec-Labrador, the Cordilleran region, and on Baffin Island.Our analysis includes the recognition of approximately 500 relative-age relationships from crosscuttinglineations. Together with previously published striae and till fabric data, these are used as the basis forrelative-age assignments of regional flow patterns. For the reconstruction of the most probable ice sheetevolution sequence we employ a stepwise inversion scheme with a clearly defined strategy for delineatingcoherent landforms swarms (reflecting flow direction and configuration), and linking these topreviously published constraints on relative and absolute chronology. Our results reveal that icedispersalcentres in Keewatin and Quebec were dynamically independent for most of pre-LGM time andthat a massive Quebec dispersal centre, rivalling the LGM in extent, existed at times when the SW sectorof the ice sheet had not yet developed. The oldest flow system in eastern Quebec-Labrador (Atlanticswarm had an ice divide closer to the Labrador coast than later configurations). A northern Keewatin-Central Arctic Ice Sheet existed prior to the LGM, but is poorly chronologically constrained. There is alsoevidence for older and more easterly Cordilleran Ice Sheet divide locations than those that prevailedduring the Late Wisconsinan. In terms of ice sheet build-up dynamics, it appears that “residual” ice capsafter warming phases may have played an important role. In particular, the location and size of remnantice masses at the end of major interstadials, i.e. OIS 5c and 5a, must have been critical for subsequentbuild-up patterns, because such remnant “uplands” may have fostered much more rapid ice sheetgrowth than what would have occurred on a fully deglaciated terrain. The ice-sheet configuration duringstadials would also be governed largely by the additional topography that such “residual” ice constitutesbecause of inherent mass balance-topography feedbacks.

  • 45. Lifton, Nathaniel
    et al.
    Beel, Casey
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kassab, Christine
    Rogozhina, Irina
    Heermance, Richard
    Oskin, Michael
    Burbank, Douglas
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, Marc
    Goehring, Brent M.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Ivanov, Mikhail
    Li, Yanan
    Li, Yingkui
    Petrakov, Dmitry
    Usubaliev, Ryskul
    Codilean, Alexandru T.
    Chen, Yixin
    Harbor, Jon
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Constraints on the late Quaternary glacial history of the Inylchek and Sary-Dzaz valleys from in situ cosmogenic Be-10 and Al-26, eastern Kyrgyz Tian Shan2014In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 101, p. 77-90Article in journal (Refereed)
    Abstract [en]

    Paleoclimatic constraints from regions at the confluence of major climate systems are particularly important in understanding past climate change. Using geomorphic mapping based on remote sensing and field investigations, combined with in situ cosmogenic Be-10 and Al-26 dating of boulders associated with glacial landforms, we investigate the chronology of past glaciation in the Inylchek and Sary-Dzaz valleys in the eastern Kyrgyz Tian Shan, a tectonically active area with some of the highest peaks in the world outside of the Himalayas. Cosmogenic Be-10 and (26) Al exposure ages of boulders on moraines record up to five glacial advances including: Lateglacial age lateral moraine remnants and meltwater channels in the upper Inylchek Valley; Last Glacial Maximum (LGM, Marine Oxygen Isotope Stage [MIS] 2) moraines in the Sary-Dzaz Valley and in a terminal moraine complex at the west end of the Inylchek Valley, overriding older moraines; an MIS 4 or 5 moraine remnant above the Inylchek terminal moraine complex; and an older high moraine remnant down-valley from the confluence of the Inylchek and Sary-Dzaz valleys. The evidence for glacial extent in this study is consistent with a limited ice expansion hypothesis for Tian Shan glaciation. Published results from the western and central Kyrgyz Tian Shan do not show evidence for significant LGM glacier expansion, which in combination with the results presented here, indicate a spatial variation in glacier records along the Tian Shan. This may reflect either paleoclimatic gradients or the impact of local physiographic conditions on responses to regional climate change, or both.

  • 46. Stokes, Chris R.
    et al.
    Tarasov, Lev
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Cronin, Thomas M.
    Fisher, Timothy G.
    Gyllencreutz, Richard
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hindmarsh, Richard C. A.
    Hughes, Anna L. C.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Livingstone, Stephen J.
    Margold, Martin
    Stockholm University, Faculty of Science, Department of Physical Geography. Durham University, UK.
    Murton, Julian B.
    Noormets, Riko
    Peltier, W. Richard
    Peteet, Dorothy M.
    Piper, David J. W.
    Preusser, Frank
    Renssen, Hans
    Roberts, David H.
    Roche, Didier M.
    Saint-Ange, Francky
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Teller, James T.
    On the reconstruction of palaeo-ice sheets: Recent advances and future challenges2015In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 125, p. 15-49Article, review/survey (Refereed)
    Abstract [en]

    Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding mechanisms of global climate change and associated sea-level fluctuations in the past, present and future. The significance of palaeo-ice sheets is further underlined by the broad range of disciplines concerned with reconstructing their behaviour, many of which have undergone a rapid expansion since the 1980s. In particular, there has been a major increase in the size and qualitative diversity of empirical data used to reconstruct and date ice sheets, and major improvements in our ability to simulate their dynamics in numerical ice sheet models. These developments have made it increasingly necessary to forge interdisciplinary links between sub-disciplines and to link numerical modelling with observations and dating of proxy records. The aim of this paper is to evaluate recent developments in the methods used to reconstruct ice sheets and outline some key challenges that remain, with an emphasis on how future work might integrate terrestrial and marine evidence together with numerical modelling. Our focus is on pan-ice sheet reconstructions of the last deglaciation, but regional case studies are used to illustrate methodological achievements, challenges and opportunities. Whilst various disciplines have made important progress in our understanding of ice-sheet dynamics, it is clear that data-model integration remains under-used, and that uncertainties remain poorly quantified in both empirically-based and numerical ice-Sheet reconstructions. The representation of past climate will continue to be the largest source of uncertainty for numerical modelling. As such, palaeo-observations are critical to constrain and validate modelling. State-of-the-art numerical models will continue to improve both in model resolution and in the breadth of inclusion of relevant processes, thereby enabling more accurate and more direct comparison with the increasing range of palaeo-observations. Thus, the capability is developing to use all relevant palaeo-records to more strongly constrain deglacial (and to a lesser extent pre-LGM) ice sheet evolution. In working towards that goal, the accurate representation of uncertainties is required for both constraint data and model outputs. Close cooperation between modelling and data-gathering communities is essential to ensure this capability is realised and continues to progress.

  • 47.
    Stroeven, Arjen
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Harbor, Jon
    Zhou, Liping
    Li, Yinkui
    Caffee, Marc
    Ma, Haizhou
    Liu, Gengnian
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Paleoglaciology of the Bayan Har Mountain area, eastern Tibetan Plateau2006In: Asian Conference on Permafrost, 2006Conference paper (Refereed)
    Abstract [en]

    The glacial history of the Tibetan Plateau is a topic of considerable interest because of its significance for regional and global environmental reconstructions, and its interaction with variations in monsoon strength and plateau uplift. Published glacial reconstructions for the last glaciation range from a large ice sheet covering the entire Tibetan Plateau to extended valley glaciation forming discrete glaciated mountain blocks. Although current chronologies appear to underpin the restricted glaciation model, there appears to be enough regional variation to motivate further study, especially the glacial history predating the last glaciation. We therefore study the glacial history of a large upland section of the eastern Tibetan Plateau centered on the currently unglaciated Bayan Har Mountains (BHM), partly because chronological constraints are entirely absent, and partly because the area may once have been covered by an ice sheet of intermediate proportions. The BHM area, which houses the headwaters of the Huang He (Yellow River), contains a wide array of glacial deposits and morphologies. Moreover, it appears that superseding glaciations were ever limiting in extent and the area therefore presents optimal conditions to investigate glaciations over long time periods.

    We report from an on-going investigation into the extent and chronology of Quaternary glaciers in this region, manifested in glacial deposits and landforms (e.g., erratics, end moraines, tills and trough valleys). Previous studies have indicated the occurrence of two phases of mountain glaciation during the last glaciation (OIS 2-4), with mountain glaciers distributed around the highest summits, and two prior glaciations of ice sheet glaciation character (the penultimate glaciation, OIS 6, and the Huang He ice sheet, OIS 12).

    We mapped the glacial morphology of the area using satellite images and a DEM of 90 m resolution. Large-scale glacial landforms such as cirques, glacial troughs and U-shaped valleys indicate repeated glaciations, and so do series of moraine ridges and meltwater channels. The abundance of glacial traces detectable through remote sensing techniques diminish with decreasing elevation, and it appears that evidence for former ice sheets are based mainly on sedimentary evidence.

    In an introductory field work in 2005, surface boulders (including erratics) and boulders in till profiles have been sampled for dating using terrestrial cosmogenic nuclide (TCN) concentrations in quartz. Sampling was carried out along a 300 km stretch of the Qingkang highway, crossing the 80,000 km2 area of the Huang He ice sheet. We intend to present these first TCN results at the meeting.

    Our study will present new data for the paleoglaciology of the eastern Tibetan Plateau, and will contribute to the resolution of questions such as:

    • What glacial fluctuations occurred in the BHM area throughout the last glaciation?

    • When did glaciation pre-dating the last glaciation occur?

    • Was the area ever covered by an ice sheet?

    • What is the relation Tibetan glaciation – uplift – climate variations?

    These are questions of special significance also for former periglacial conditions, as reconstructed glaciers and ice sheets had a fundamental effect on regional paleoenvironmental conditions.

  • 48.
    Stroeven, Arjen
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Geomorphology of the Huang He ice sheet area: towards a reconstruction of the glacial history of the northeastern Tibetan Plateau2006In: INQUA conference on Mountain Glaciation, 2006Conference paper (Refereed)
    Abstract [en]

    Recent terrestrial cosmogenic nuclide (TCN) studies on end moraines of the Tibetan Plateau have yielded a first synthesis of the timing of mountain glacier and ice field maximum extents at discrete times in the past. Although these allow important constraints on the presence of expanded ice on the plateau, they don’t address the question of the presence of areally more extensive ice sheet configurations where mountain ice complexes from discrete mountain blocks coalesce to form larger bodies. Two ice sheets hypothesised to have covered parts of the Tibetan Plateau are the Tibetan ice sheet and the areally much more restricted Huang He ice sheet. In this study we have focussed on the hypothesised Huang He ice sheet area in the headwaters of the Huang He and Yangtze rivers on the north-eastern margin of the Tibetan Plateau.

    Two mountain blocks from which ice might have emanated to inundate the plateau surface around it and form the ice sheet are the marginally-located Anyemaqen and centrally-located Bayan Har Mountains. Of these the Anyemaqen is located closer to the edge of the plateau, is higher, wetter, and is ornamented with glaciers today, which, according to TCN studies have been more extensive during marine oxygen isotope stages 3, 2, and 1.

    Using Landsat 7 ETM+ satellite imagery we have mapped the glacial geomorphology of the entire hypothesised Huang He ice sheet area (50,000-70,000 km2) and concentrated our TCN field sampling to its core area, the Bayan Har Mountains. The area displays widespread morphological evidence of glacial erosion and deposition, particularly around the higher mountain blocks. The erosional landforms include large-scale glacial troughs, U-shaped valleys and occasional lake basins, and small-scale lateral meltwater channels. The depositional landforms include primarily lateral and end-moraines, but also hummocky moraines and drumlins. Field inspection has yielded observations of tills and erratic boulders. Taken together, these traces comprise an impressive record of multiple large-scale erosional events as witnessed by cross-cutting relationships of glacial valleys and multiple glacier advances through the Bayan Har Mountain valleys, some of which terminated onto the plateau surface, by the presence of suites of end-moraines and associated meltwater traces.

    The mapping exercise thus far has established a clear patchiness to the erosional imprint of ice in the uplands comprising the Huang He ice sheet area. Although the integrated imprint of erosion is clear and displays a pattern of topographically-forced selective linear erosion, the rates of glacial landscape change in the absence of TCN measurements remains unknown.

    We note that except for the arguable presence of tills and the reported, but not confirmed, presence of erratics beyond the mountain fronts, we have not been able to establish firm evidence of ice coverage on the intervening plateau surfaces. Rather, many areas display a distinct non-glacial morphology with welldeveloped fluvial valley systems and basins infilled with alluvial deposits. This casts some doubt on the concept of the Huang He ice sheet, although one may argue that, if of considerable age, few glacial traces may have survived degradational processes. Moreover, we conclude that the break in slope between the youthful steep fluvial landscapes of the Huang He and Yangtze rivers and the relict gentle sloping surface of the Tibetan Plateau almost entirely coincides with the outline of the Huang He ice sheet bordering these rivers. This could be used to further question the reality of the Huang He ice sheet or, if indisputable further evidence can be uncovered in the years to come, the coincidence of borders could indicate that the ice sheet was larger but that evidence for this is now flowing down the rivers.

    Finally, an ambitious TCN and OSL sampling campaign in the Bayan Har Mountains region with our colleagues from the USA (Caffee, Harbor, Li) and China (Zhou, Liu, Ma) will likely shed light on the timing of glacial advances through the dating of end moraines, erratics and till stratigraphies and establish contemporary landscape catchment erosion rates through the analysis of river bank sediment TCN concentrations.

  • 49.
    Stroeven, Arjen
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Harbor, Jon
    Li, Yingkui
    Zhou, Liping
    Caffee, Marc
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Ma, Haizhou
    Liu, Gengnian
    Landscape analysis of the Huang He headwaters, NE Tibetan Plateau — Patterns of glacial and fluvial erosion2009In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 103, no 2, p. 212-226Article in journal (Refereed)
    Abstract [en]

    The large-scale geomorphology of the Huang He (Yellow River) headwaters, centered around the Bayan Har Shan (5267 m asl) in the northeastern part of the Tibetan Plateau, is dominated by an uplifted remnant of a low-relief relict plateau with several mountain ranges. We have performed geomorphological mapping using SRTM topographic data and Landsat 7 ETM+ satellite imagery to evaluate landscape characteristics and patterns, and to investigate the relative importance of different erosional processes in the dissection of this plateau remnant. The distribution of valley morphologies indicates that the eastern and southern margins of the plateau remnant have been extensively dissected by the Huang He and Chang Jiang (Yangtze) rivers and associated tributaries, while the mountain ranges have valley morphologies with U-shaped cross-sections that indicate large impacts from glacial erosion during Quaternary glaciations.

    An east-west decrease in the abundance of glacial valleys in mountains above 4800 m asl suggests that the diminishing size of the mountain blocks, coupled with increased continentality, resulted in more restricted glaciations to the west. Glacial valleys in mountain blocks on the plateau remnant are wider and deeper than adjacent fluvial valleys. This indicates that, integrated over time, the glacial system has been more effective in eroding the mountains of the relict upland surface than the fluvial system. This erosion relationship is reversed, however, on the plateau margin where dramatic fluvial rejuvenation in valleys that are part of the Huang He and Chang Jiang watersheds has consumed whatever glacial morphology existed. A remarkable correspondence exists between the outline of the relict plateau remnant and the outline that has been proposed for the Huang He Ice Sheet. This coincidence could mean that the Huang He Ice Sheet was larger than originally proposed, but that evidence for this has been consumed by fluvial incision at the plateau margin. Alternatively, this coincidence could indicate that what has been described as an ice sheet border is merely the outline of a relict plateau landscape.

    In apparent support of the latter, the absence of large-scale glacial geomorphological evidence on the plains of the relict plateau surface is not consistent with the hypothesis of a Huang He Ice Sheet.

  • 50.
    Stroeven, Arjen P.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University .
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Morén, Björn M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Glacial geomorphology of the Tian Shan2013In: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 9, no 4, p. 505-512Article in journal (Refereed)
    Abstract [en]

    The glacial geomorphology of the Tian Shan has been mapped, with the study area covering almost 638,000km(2). The map, designed to be printed at A0 size due to the elongated shape of the mountain range, is presented at a scale of 1:1,100,000. Five glacial landform categories are presented; glacial valleys, marginal moraines, glacial lineations, hummocky terrain and meltwater channels. These landform categories were mapped using the Shuttle Radar Topography Mission (SRTM) digital elevation model (90m resolution), Landsat 7 ETM+ satellite imagery (30m resolution), and images contained in Google Earth. The mapped landforms were created by glaciers that were restricted to mountain areas and their immediate surroundings.

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