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  • 1. Andersen, J. L.
    et al.
    Egholm, D. L.
    Knudsen, M. F.
    Linge, H.
    Jansen, J. D.
    Goodfellow, Bradley W.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pedersen, V. K.
    Tikhomirov, D.
    Olsen, J.
    Fredin, O.
    Pleistocene Evolution of a Scandinavian Plateau Landscape2018In: Journal of Geophysical Research - Earth Surface, ISSN 2169-9003, E-ISSN 2169-9011, Vol. 123, no 12, p. 3370-3387Article in journal (Refereed)
    Abstract [en]

    The origins and Pleistocene evolution of plateau landscapes along passive continental margins of the North Atlantic have been debated for more than a century. A key question in this debate concerns whether glacial and periglacial surface processes have substantially eroded plateau areas during late Cenozoic climatic cooling or whether the plateaus have mainly been protected from erosion by cold-based and largely nonerosive ice sheets. Here we investigate the Pleistocene evolution of a prominent plateau landscape in Reinheimen National Park, southern Norway. We estimate erosion rates across the plateau via inverse modeling of 141 new cosmogenic Be-10 and Al-26 measurements in regolith profiles and bedrock. We combine these results with sedimentological analyses of the regolith. In the vicinity of Reinheimen's regolith-covered summits, the combination of uniformly slow erosion (<10m/Myr) and near-parabolic slope geometry suggests long-term equilibrium with the presently active periglacial mass-wasting processes. Outside summit areas, erosion is faster (up to >50m/Myr), possibly due to episodic glacial erosion. Despite some indications of chemical alteration, such as grusic saprolite and small amounts of secondary minerals, the fine regolith comprises low clay/silt ratios and is dominated by primary minerals with no sign of dissolution. Together with our modeled erosion rates, this indicates that the regolith cover formed, and continues to develop, during the cold climate of the Late Pleistocene. Plain Language Summary Plateaus dissected by steep-sided valleys and fjords are common landscape elements within the mountains bordering the North Atlantic. Most of these plateaus have likely experienced millions of years of near-freezing temperatures and were repeatedly covered by ice sheets during recent glacial periods. Yet the imprint of cold-climate erosion processes on the plateau landscape evolution remains poorly understood. Here we investigate the Pleistocene evolution of an extensive Scandinavian plateau landscape in Reinheimen National Park, southern Norway. We measure cosmogenic nuclides within the surficial layers of rock and sediment on the plateau. The concentration of these cosmogenic nuclides reflects the erosion of the plateau landscape and thereby the impact of recent cold-climate surface processes. We find that erosion has influenced the plateaus within the latest glacial cycles. In the vicinity of the highest, sediment-clad summits, the plateau shape is determined by processes related to freezing and thawing of rocks and sediment, while the influence of erosion by glaciers and streams increases further downslope.

  • 2.
    Fritzon, Ruben
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Goodfellow, Bradley
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Skelton, Alasdair
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Estholm, Madelene
    Caffee, Marc
    Evaluating geochemical evidence of earthquake periodicity, Sparta Fault, Southern GreeceManuscript (preprint) (Other academic)
    Abstract [en]

    Determining prehistoric earthquake periodicity and magnitudes is important for risk assessments in seismically active areas. We evaluate a geochemical method, which has previously been used to identify prehistoric slips on normal fault scarps through an analysis of variations in the concentration of rare earth elements and Y (REE-Y) along vertical transects. Our study object is the Sparta Fault, a normal fault in southern Greece, developed in limestone and previously documented, and dated using 36Cl, to have been last active 464 BC. From geochemical analyses of 39 fault rock samples, we conclude that REE-Y concentrations correlate strongly with the abundance of quartz and possibly other heterogeneities in the fault scarp. Because the sampled fault rock is a protocataclasite, formed at depth, variations in the abundance of quartz are not associated with prehistoric movements along the fault. We therefore conclude that geochemical evidence does not provide a reliable paleoseismic proxy for fault movement. We also present data indicating a co-variation between quartz and 36Cl concentrations, which we suggest requires a re-examination of this widely used application of the cosmogenic nuclide surface exposure dating method.

  • 3.
    Goodfellow, Bradley
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Relict non-glacial surfaces in formerly glaciated landscapes2007In: Earth-Science Reviews, Vol. 80, no 1-2, p. 47-73Article in journal (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. Relict non-glacial surfaces are distinguishable from glacial surfaces by large-scale morphologies, including rounded summits, fluvial valleys, and cryoplanation terraces and pediments, and the presence of tors, blockfields, and/or saprolites. Preservation during glaciation occurs either through coverage by non-erosive, cold-based, ice or as nunataks. Although surface morphologies and denudation rates indicate a continuous non-glacial surface history since pre-glacial times, relict non-glacial surfaces are dynamic features that have evolved during the Quaternary. Depending on spatial variables such as lithology, slope, regolith cover, 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. Denudation rates also display high temporal variability, with much surface evolution having perhaps occurred soon after the initial onset of glaciation or during paraglacial phases. While some parts of non-glacial landscapes are currently active, others may be largely inactive relicts of past higher energy regimes. Although non-glacial surfaces are dynamic much remains to be determined regarding surface denudation rates and the magnitude of morphological changes over time.

  • 4.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, D.
    Stroeven, Arjen
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Caffee, M.
    Bintanja, R.
    Vertically mixed and unmixed: Do surface features tell the whole story? An investigation of glacial regolith profiles using in-situ produced cosmogenic radionuclides2007In: EOS, 2007Conference paper (Refereed)
    Abstract [en]

    Whether a regolith is unmixed or mixed is critical to determining its erosion rate or age from in situ-produced cosmogenic nuclides. We use in situ-produced 10Be and 26Al in quartzite clasts extracted from depth profiles to investigate mixing of a periglacially-sorted till blanketing a plateau in the northern Swedish mountains. Our data indicate significant intra-site variations from a completely unmixed to a fully mixed regolith. We conclude that caution must be exercised in assuming that an entire regolith is either unmixed or mixed from interspersed depth profiles and that the degree of mixing may differ significantly from that indicated by observation of surface features. From the difference between the surface isotope concentration of an unmixed profile and the average isotope concentration of a fully mixed profile, we confirm that the regolith is a glacial till and that it could have been emplaced in a single event. Incorporating isotope concentrations, 26Al/10Be ratios, and an isostasy and ice sheet burial model we date the till emplacement to the Saalian glaciation (~ 200 to 130 ka).

  • 5.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stephenson, Wayne
    Beach morphodynamics in a strong-wind bay: a low energy environment?2005In: Marine Geology, Vol. 214, p. 101-116Article in journal (Refereed)
    Abstract [en]

    The morphodynamic behaviour of a multibarred beach in a fetch-limited, strong-wind bay (Seaford Beach, SE Australia) was examined during both high and low-energy conditions, and considered in the context of a definition of low-energy provided in the literature. Measurements of nearshore waves, currents, and morphology revealed a bimodal behaviour. Under initial low-energy conditions, the beach exhibited a “low tide terrace” state, and waves and currents were of very low magnitude. During subsequent high-energy conditions, the beach demonstrated dynamic behaviour through the formation of a transitional “transverse bar and rip – rhythmic bar and beach,” and migration of the middle bar, with the morphology remaining in an arrested high-energy state during intervening low-energy periods. Although broadly conforming to the morphodynamic model, the beach did exhibit some distinct characteristics attributable to its fetch-limited location; limited progression through the morphodynamic model, and the importance of wind direction and magnitude in governing morphodynamic behaviour. Furthermore, rip currents were not significant in driving beach change through intermediate states. The presence of infragravity energy in the storm wave spectra; a dissipative, multibarred surf zone; dynamic inner and middle bars; and the attainment of a “transitional transverse bar and rip – rhythmic bar and beach” state during rising wave conditions, underline Seaford Beach as “bimodal”, exhibiting process and morphologic features of both higher and lower-energy beaches. As an example of a beach in a strong-wind bay, Seaford illustrates that not all fetch-limited beaches are low-energy. Furthermore, the presence of infragravity energy in a highly fetch-limited environment indicates that infragravity energy may occur commonly in fetch-limited environments that are subject to periodic strong winds; a process that has remained largely unrecognised.

  • 6.
    Goodfellow, Bradley
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stephenson, Wayne
    Role of infragravity energy in bar formation in a strong wind bay: Observations from Seaford Beach, Port Phillip Bay, Australia2008In: Geographical Research, ISSN 1745-5863, Vol. 46, no 2, p. 208-223Article in journal (Refereed)
    Abstract [en]

    Measurements of the surf zone wave field and morphology were obtained from a multi-barred beach in a fetch-limited, strong-wind bay (Seaford, SE Australia) during both low- and high-energy conditions. Analysis of the infragravity energy present during high-energy events (onshore winds > 7 ms-1) revealed that it was broad-banded, consisting of a mixture of standing and progressive motions and displaying daily variations in standing wave length scales. Infragravity standing waves were therefore not considered significant to the formation and migration of bars at Seaford during this study, with bar behaviour during high energy events potentially attributable to either breaking wave-bed return flow and/or self-organisational mechanisms.

  • 7.
    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

  • 8.
    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.

  • 9.
    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.

  • 10.
    Goodfellow, Bradley W.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stanford University, USA.
    A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins2012In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 57, p. 121-135Article in journal (Refereed)
    Abstract [en]

    A review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation. If present, this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated. These blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm, Neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the Quaternary. Based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields, other regoliths in periglacial settings, and regoliths from non-periglacial settings, a fingerprint of chemical weathering in periglacial landscapes was identified. A mobile regolith origin under, at least seasonal, periglacial conditions is indicated where clay(%) ≤ 0.5*silt(%) + 8 across a sample batch. This contrasts with a mobile regolith origin under non-periglacial conditions, which is indicated where clay(%) ≥ 0.5*silt(%) − 6 across a sample batch with clay(%) ≥ 0.5*silt(%) + 8 in at least one sample. A range of secondary minerals, which frequently includes interstratified minerals and indicates high local variability in leaching conditions, is also commonly present in regoliths exposed to periglacial conditions during their formation. Clay/silt ratios display a threshold response to temperature, related to the freezing point of water, but there is little response to precipitation or regolith residence time. Lithology controls clay and silt abundances, which increase from felsic, through intermediate, to mafic compositions, but does not control clay/silt ratios. Use of a sedigraph or Coulter Counter to determine regolith granulometry systematically indicates lower clay abundances and intra-site variability than use of a pipette or hydrometer. In contrast to clay/silt ratios, secondary mineral assemblages vary according to regolith residence time, temperature, and/or precipitation. A microsystems model is invoked as a conceptual framework in which to interpret the concurrent formation of the observed secondary mineral ranges. According to the fingerprint of chemical weathering in periglacial landscapes, there is generally no evidence of blockfield origins under warm Neogene climates. Nearly all blockfields appear to be a product of Quaternary physical and chemical weathering. A more dominant role for periglacial processes in further bevelling elevated, low relief, non-glacial surface remnants in otherwise glacially eroded landscapes is therefore indicated.

  • 11.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stanford University, USA.
    Chadwick, Oliver A.
    Hilley, George E.
    Depth and character of rock weathering across a basaltic-hosted climosequence on Hawai` i2014In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 39, no 3, p. 381-398Article in journal (Refereed)
    Abstract [en]

    Using field observations and geochemical and digital terrain analyses, we describe the structure and thickness of the regolith across a climosequence on the island of Hawaii to gain insight into the relative roles of precipitation and the near-surface hydrologic structure in determining weathering patterns. In the wet portion of the climosequence, where the long-term water balance is positive, the regolith thickness reaches an observed maximum of similar to 40m and appears limited by the geomorphic base-level of the landscape. However, even within this thick regolith, distinct units of varying weathering intensity occur; the vertical ordering of which largely reflects differences in the initial permeability structure of the basalt flows rather than a systematic decrease in weathering intensity downwards from the ground surface. In the dry portion of the climosequence, where the long-term water balance is negative, the regolith thickness is confined to similar to 1m, is highly dependent on the inferred permeability structure of the basalt flows, and is independent of geomorphic base-level. Weathering intensity also varies according to permeability structure and decreases in this thin regolith with distance beneath the ground surface. The abrupt change in regolith depth and character that coincides with the transition from net-positive to net-negative long-term water balance implies that small changes in precipitation rates around a neutral water balance result in large changes in the distribution and depth of weathering. Together our observations indicate that the distribution and depth of weathering in basalts (and probably other lithologies) might be best understood by considering how precipitation interacts with the complicated near-surface permeability structure over regolith-forming timescales to weather rock in the vadose zone.

  • 12.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Stanford University, USA; Lund University, Sweden.
    Hilley, George E.
    Webb, Samuel M.
    Sklar, Leonard S.
    Moon, Seulgi
    Olson, Christopher A.
    The chemical, mechanical, and hydrological evolution of weathering granitoid2016In: Journal of Geophysical Research - Earth Surface, ISSN 2169-9003, E-ISSN 2169-9011, Vol. 121, no 8, p. 1410-1435Article in journal (Refereed)
    Abstract [en]

    Surprisingly few studies connect the chemical, mechanical, and hydrological evolution of rock as it weathers to saprolite and soil. We assess this coevolution in granodiorite from Monterey Peninsula, California, by measuring changes in bulk chemistry, mineralogy, volumetric strain, the oxidation state of Fe in biotite crystals, tensile strength, abrasion rate, connected porosity, and hydraulic conductivity in samples covering a range of weathering grades. We identify the oxidative dissolution of biotite as the key chemical reaction because of the volumetric expansion that accompanies formation of altered biotite and precipitation of ferrihydrite. We show how the associated accumulation of elastic strain produces an energy density that is sufficient to support rock fracturing over length scales equivalent to constituent crystals. The resulting intragranular and intergranular cracking profoundly reduces tensile strength and increases the abrasion rate, connected porosity, and hydraulic conductivity of the rock matrix. These changes increase the rate of plagioclase weathering, and ultimately the rock disintegrates into grus and clay. Major changes in rock properties can occur with only minor element leaching, and the threshold behavior of weathering that arises from the coevolution of chemical, hydrological, and mechanical properties may be difficult to capture using simplified weathering models that fail to incorporate these properties. Our results, which combine the mechanical and hydrological evolution of weathering rock with more common measurements of chemical changes, should help to more accurately model the effects of, and mechanical and hydrological feedbacks upon, chemical weathering of rock.

  • 13.
    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

  • 14.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Lund University, Sweden.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, D.
    Fredin, O.
    Derron, M. -H.
    Bintanja, R.
    Caffee, M. W.
    Arctic-alpine blockfields in the northern Swedish Scandes: late Quaternary - not Neogene2014In: Earth Surface Dynamics, ISSN 2196-6311, Vol. 2, no 2, p. 383-401Article in journal (Refereed)
    Abstract [en]

    Autochthonous blockfield mantles may indicate alpine surfaces that have not been glacially eroded. These surfaces may therefore serve as markers against which to determine Quaternary erosion volumes in adjacent glacially eroded sectors. To explore these potential utilities, chemical weathering features, erosion rates, and regolith residence durations of mountain blockfields are investigated in the northern Swedish Scandes. This is done, firstly, by assessing the intensity of regolith chemical weathering along altitudinal transects descending from three blockfield-mantled summits. Clay / silt ratios, secondary mineral assemblages, and imaging of chemical etching of primary mineral grains in fine matrix are each used for this purpose. Secondly, erosion rates and regolith residence durations of two of the summits are inferred from concentrations of in situ-produced cosmogenic Be-10 and Al-26 in quartz at the blockfield surfaces. An interpretative model is adopted that includes temporal variations in nuclide production rates through surface burial by glacial ice and glacial isostasy-induced elevation changes of the blockfield surfaces. Together, our data indicate that these blockfields are not derived from remnants of intensely weathered Neogene weathering profiles, as is commonly considered. Evidence for this interpretation includes minor chemical weathering in each of the three examined blockfields, despite consistent variability according to slope position. In addition, average erosion rates of similar to 16.2 and similar to 6.7 mm ka(-1), calculated for the two blockfield-mantled summits, are low but of sufficient magnitude to remove present blockfield mantles, of up to a few metres in thickness, within a late Quaternary time frame. Hence, blockfield mantles appear to be replenished by regolith formation through, primarily physical, weathering processes that have operated during the Quaternary. The persistence of autochthonous blockfields over multiple glacial-interglacial cycles confirms their importance as key markers of surfaces that were not glacially eroded through, at least, the late Quaternary. However, presently blockfield-mantled surfaces may potentially be subjected to large spatial variations in erosion rates, and their Neogene regolith mantles may have been comprehensively eroded during the late Pliocene and early Pleistocene. Their role as markers by which to estimate glacial erosion volumes in surrounding landscape elements therefore remains uncertain.

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  • 15.
    Goodfellow, Bradley W.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Lund University, Sweden.
    Viola, Giulio
    Bingen, Bernard
    Nuriel, Perach
    Kylander-Clark, Andrew R. C.
    Palaeocene faulting in SE Sweden from U-Pb dating of slickenfibre calcite2017In: Terra Nova, ISSN 0954-4879, E-ISSN 1365-3121, Vol. 29, no 5, p. 321-328Article in journal (Refereed)
    Abstract [en]

    Estimating the timing of faulting is crucial to modelling tectonics, palaeoseismicity, landscape evolution and fault mechanics. Four slickenfibre calcite samples from a conjugate strike-slip fault set in a platformal limestone, SE Sweden, were dated using U-Pb. Three of the samples yielded an average age of 64.8 +/- 6.5Ma, while the fourth yielded a marginally younger age of 54.7 +/- 5.5Ma. Precipitation of the fibres is interpreted as syn-deformational. Age uncertainty and dispersion reflect incorporation of common Pb and tiny host-rock components into the dated calcite and/or possible fault reactivation through ca. 55Ma. We infer from crystal characteristics, stable isotopes (O-18 and C-13) and rare-earth elements that fibres formed in an environment rich in deep-seated fluids, at temperatures of 40-200 degrees C, with shear stresses exceeding 10 MPa and at a maximum burial depth of c. 4km. This Palaeocene faulting may reflect far-field stresses from shortening in the Alps.

  • 16.
    Stroeven, Arjen
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Goodfellow, Bradley
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Fabel, Derek
    Fredin, Ola
    Derron, M.-H.
    Caffee, M.W.
    Bintanja, R.
    Blockfields of Neogene origin: Challenging the paradigm2007In: EOS, 2007Conference paper (Refereed)
    Abstract [en]

    The prevailing paradigm for cold-climate in situ blockfields is that they are remnants of Neogene deep weathering profiles. This opinion is frequently based on the presence of large quantities of interstitial silt and clay and/or the presence of clay minerals, such as gibbsite and kaolinite. Using in situ-produced cosmogenic isotopes 10Be and 26Al, XRD, and XRF to study blockfield regolith in the northern Swedish mountains, we challenge this paradigm. Incorporating surface burial by ice sheets, the isostatic response to ice sheet loading and unloading, and subaerial surface erosion, the cosmogenic data indicate that the regolith has been accumulating nuclides for up to 464.5 ka. The ubiquitous presence of chlorite makes it impossible to distinguish kaolinite according to standard XRD techniques. However, gibbsite is present in glacial till in addition to wet- location blockfield regolith. Coupled with the ubiquitous presence of poorly crystallized hydroxides, vermiculization in wet-locations, and an absence of smectite, incipient chemical weathering is indicated. Furthermore, XRF data indicate dominance of the interstitial fine matrix by a foreign component, likely of aeolian origin. All of our observations can be explained by processes operating within the Quaternary timeframe. Because we do not need to appeal to Neogene deep weathering to account for the characteristics of blockfields in the northern Swedish mountains we conclude that these blockfields may have Quaternary origins.

  • 17.
    Stroeven, Arjen P.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Kleman, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Fabel, Derek
    Fredin, Ola
    Goodfellow, Bradley W.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Lund University, Sweden.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography. Purdue University, USA.
    Jansen, John D.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Potsdam, Germany.
    Olsen, Lars
    Caffee, Marc W.
    Fink, David
    Lundqvist, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Rosqvist, Gunhild C.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Bergen, Norway.
    Strömberg, Bo
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Deglaciation of Fennoscandia2016In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 147, no SI, p. 91-121Article in journal (Refereed)
    Abstract [en]

    To provide a new reconstruction of the deglaciation of the Fennoscandian Ice Sheet, in the form of calendar-year time-slices, which are particularly useful for ice sheet modelling, we have compiled and synthesized published geomorphological data for eskers, ice-marginal formations, lineations, marginal meltwater channels, striae, ice-dammed lakes, and geochronological data from radiocarbon, varve, optically-stimulated luminescence, and cosmogenic nuclide dating. This is summarized as a deglaciation map of the Fennoscandian Ice Sheet with isochrons marking every 1000 years between 22 and 13 cal kyr BP and every hundred years between 11.6 and final ice decay after 9.7 cal kyr BP. Deglaciation patterns vary across the Fennoscandian Ice Sheet domain, reflecting differences in climatic and geomorphic settings as well as ice sheet basal thermal conditions and terrestrial versus marine margins. For example, the ice sheet margin in the high-precipitation coastal setting of the western sector responded sensitively to climatic variations leaving a detailed record of prominent moraines and other ice-marginal deposits in many fjords and coastal valleys. Retreat rates across the southern sector differed between slow retreat of the terrestrial margin in western and southern Sweden and rapid retreat of the calving ice margin in the Baltic Basin. Our reconstruction is consistent with much of the published research. However, the synthesis of a large amount of existing and new data support refined reconstructions in some areas. For example, the LGM extent of the ice sheet in northwestern Russia was located far east and it occurred at a later time than the rest of the ice sheet, at around 17-15 cal kyr BP. We also propose a slightly different chronology of moraine formation over southern Sweden based on improved correlations of moraine segments using new LiDAR data and tying the timing of moraine formation to Greenland ice core cold stages. Retreat rates vary by as much as an order of magnitude in different sectors of the ice sheet, with the lowest rates on the high-elevation and maritime Norwegian margin. Retreat rates compared to the climatic information provided by the Greenland ice core record show a general correspondence between retreat rate and climatic forcing, although a close match between retreat rate and climate is unlikely because of other controls, such as topography and marine versus terrestrial margins. Overall, the time slice reconstructions of Fennoscandian Ice Sheet deglaciation from 22 to 9.7 cal kyr BP provide an important dataset for understanding the contexts that underpin spatial and temporal patterns in retreat of the Fennoscandian Ice Sheet, and are an important resource for testing and refining ice sheet models.

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