Change search
Refine search result
1 - 18 of 18
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Sub-till glaciofluvial sediments at Hultsfred, South Swedish Upland2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 3&4, 153-159 p.Article in journal (Refereed)
    Abstract [en]

    In a gravel pit near Hultsfred, at the eastern margin of the South Swedish Upland, gravelly, sandy and silty-sandy beds covered by a thick, strati?ed gravelly diamicton are exposed. Large folds and shear-planes indicate post-depositional deformation of the sorted sediments, which according to OSL dating have a maximum Middle Weichselian (,60 ka) age. The sand and gravel are interpreted as glacio?uvial sediments that were deposited laterally during a Middle Weichselian deglaciation, or possibly subglacially during the Late Weichselian. The large-scale deformation was due to glaciotectonics, caused by an overriding wet-based ice sheet during the last deglaciation. The subglacial hydrostatical pressure was high and led to the formation of downward-injected clastic dykes. A basal till, which forms the cover moraine in the area, caps the succession. The fairly frequent occurrence of sub-till sediments on the South Swedish Upland demonstrates the limited effect of glacial erosion in parts of this area. During the Last Glacial Maximum, the South Swedish Upland was an ‘island’ of slow-moving, polythermal and at least partly non-erosive ice, surrounded by faster ice-streams in the Baltic and in the Skagerrak. The ice sheet may have left its main impact on the landscape during short periods during advance and deglaciation only.

  • 2.
    Andren, Thomas
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Andren, Elinor
    Berglund, Bjorn E.
    Yu, Shi-Yong
    New insights on the Yoldia Sea low stand in the Blekinge archipelago, southern Baltic Sea2007In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 129, 277-285 p.Article in journal (Refereed)
    Abstract [en]

    One sediment core from the Jarnavik bay in Blekinge archipelago has been investigated for its content of pollen and diatoms and its chemical properties. Two levels were also dated by radiocarbon. Based on the results the sediment sequence analysed has been divided into three environmental units largely corresponding to the lithology of the sequence. A lowermost unit consisting of weakly varved and homogeneous clay was deposited during the end of the brackish phase of the Yoldia Sea at a moderate water depth. On top of this unit a gyttja-clay unit was deposited. The onset of the deposition of this unit has been dated to c. 11 100 cal. yrs. BP. An increasing organic production and increased terrestrial influence is recorded in the chemical data and a very shallow water depth is indicated in the pollen and diatom flora. These results point to conditions in a bay probably isolated from the Yoldia Sea. A local tentative shore displacement curve have been constructed and it is proposed that this unit represents the low stand at c. -18 m during the Yoldia Sea stage in this part of the Baltic Sea basin. The uppermost unit consists of homogeneous clay with a low content of organic carbon. An increasing water depth is indicated by the composition of both pollen and diatoms. The diatom flora also displays an increase in freshwater species. This environmental change was probably the result of a transgression in the beginning of the Ancylus Lake stage.

  • 3.
    Broman, Curt
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sturkell, Erik
    Fallick, Anthony E.
    Oxygen isotopes and implications for the cavity-grown quartz crystals in the Lockne impact structure, Sweden2011In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 133, no 02-jan, 101-107 p.Article in journal (Refereed)
    Abstract [en]

    Well-developed quartz crystals are found in open cavities in the intensely fractured crystalline basement of the marine-target impact structure at Lockne in central Sweden. The 458 Ma impact structure has a well-preserved crater in Precambrian granitic basement rock that is covered by resurge deposits composed of breccias and fine-grained sedimentary units of mixed Ordovician limestone, Cambrian black bituminous shales and the basement granite. Directly after the impact, the resurge deposits formed when the seawater rushed back into the crater. The residual heat from the impact facilitated a short-lived hydrothermal system accompanied by the inflowing seawater, which resulted in mineral growth in fractures and open cavities of the granite basement. The oxygen isotope values of the first-precipitated minerals, the cavity-grown quartz crystals, range from +15.2 to +16.2 parts per thousand (Vienna Standard Mean Ocean Water) and differ from those of the hosting granite basement rock with delta(18)O quartz between +10.1 and +11.7 parts per thousand. The delta(18)O values of the quartz are more consistent with derivation from a fluid of relatively high delta(18)O probably attributable to oxygen isotope exchange during seawater-rock interactions in the resurge deposits. The occurrence of organic matter in association with the cavity-grown quartz strongly indicates a relationship to the black bituminous shale in the matrix of the breccia that rests on the crater floor. Comparing the results with previously obtained oxygen data on fracture-grown calcite from Lockne shows that oxygen isotope composition of the cavity-grown quartz crystals is less variable and probably more accurately reflects the original fluid source.

  • 4.
    Greenwood, Sarah L.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Clason, Caroline C.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Mikko, Henrik
    Nyberg, Johan
    Peterson, Gustaf
    Smith, Colby A.
    Integrated use of LiDAR and multibeam bathymetry reveals onset of ice streaming in the northern Bothnian Sea2015In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 137, no 4, 284-292 p.Article in journal (Refereed)
    Abstract [en]

    Geomorphological mapping from the new LiDAR (Light Detection and Ranging)-derived digital elevation model for Sweden and a high-resolution multibeam bathymetry data-set for the Gulf of Bothnia reveals a continuous system of glacial landforms crossing the transition between the modern terrestrial and marine environments. A palaeo-ice stream in the northern Bothnian Sea is reconstructed, with an onset tributary over the present-day angstrom ngermanland-Vasterbotten coastline. Systematic contrasts in landform morphology and lineation length indicate that this ice stream comprised a relatively narrow (approximate to 40km) corridor of fast flow, flowing first SW then S, and likely fed by converging flow around the upper Bothnian Sea. The geometry and landform associations of this system imply that ice, at the time period represented here, did not flow across the Gulf of Bothnia: SSE-ward ice flow indicators on the northern Swedish coast do not correspond directly with landform assemblages of the large SE-oriented Finnish deglacial lobes. Instead, we suggest they may contribute to a late-stage fast-flow event to the S and SW. Multibeam bathymetry data offer entirely new access into the rich, landform-scale geomorphological record on the seafloor of the Gulf of Bothnia. The combination of offshore multibeam with the new terrestrial LiDAR data provides unprecedented insight into and renewed understanding of the glacial dynamics of the Bothnian Sea sector of the Fennoscandian Ice Sheet, hitherto interpreted over large areas of unmapped ice sheet bed.

  • 5. Henkel, Herbert
    et al.
    Piazolo, Sandra
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Worman, Anders
    Jing, Lanru
    A deep rock laboratory in the Dellen impact crater2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 1, 45-54 p.Article in journal (Refereed)
    Abstract [en]

    The Deep Rock Lab is a platform to establish a comprehensive subsurface bedrock characterization approach, by integrating site characterization techniques applied from different disciplines of geo-mechanics, geochemistry, hydrogeology, structural geology, lithology and geophysics, with consideration of the effects of coupled geological processes of importance for the understanding of groundwater renewal, continental shield deformations, engineering issues related to geological disposal of nuclear waste and CO2, and geothermal energy retrieval in crystalline rocks. The approach will focus on the physics and chemistry of crystalline rocks and groundwater with down-the-hole measurements of relevant variables, using and developing more efficient geo-scientific site investigation techniques for deep boreholes at a chosen site, and develop more advanced down-the-hole measurements and numerical modelling methods with more advanced inversion algorithms to help integrate data interpretations and object representations. The goal is to develop this platform into a long-term research facility that can be readily used by the scientific community for both subsurface fundamental and engineering-oriented research. Such a platform will be especially important for the education of PhD students for generations to come. The integrated drilling and research facility is suggested to be located at the Dellen site. This site has an impact crater with a large range of expected physical property changes with depth, complex and multiple thermal processes that have affected the bedrock, a favorable infrastructure and local supporting activities, and a large body of existing geo-scientific data.

  • 6. Henkel, Herbert
    et al.
    Piazolo, Sandra
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Wörman, Anders
    Jing, Lanru
    Proposal for a Deep Rock Laboratory in the Dellen Impact Crater.2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 1, 45-54 p.Article in journal (Refereed)
    Abstract [en]

    The Deep Rock Lab is a platform to establish a comprehensive subsurface bedrock characterization approach, by integrating site characterization techniques applied from different disciplines of geo-mechanics, geochemistry, hydrogeology, structural geology, lithology and geophysics, with consideration of the effects of coupled geological processes of importance for the understanding of groundwater renewal, continental shield deformations, engineering issues related to geological disposal of nuclear waste and CO2, and geothermal energy retrieval in crystalline rocks. The approach will focus on the physics and chemistry of crystalline rocks and groundwater with down-the-hole measurements of relevant variables, using and developing more efficient geo-scientific site investigation techniques for deep boreholes at a chosen site, and develop more advanced down-the-hole measurements and numerical modelling methods with more advanced inversion algorithms to help integrate data interpretations and object representations. The goal is to develop this platform into a long-term research facility that can be readily used by the scientific community for both subsurface fundamental and engineering-oriented research. Such a platform will be especially important for the education of PhD students for generations to come. The integrated drilling and research facility is suggested to be located at the Dellen site. This site has an impact crater with a large range of expected physical property changes with depth, complex and multiple thermal processes that have affected the bedrock, a favorable infrastructure and local supporting activities, and a large body of existing geo-scientific data.

  • 7. Hogdahl, Karin
    et al.
    Jonsson, Erik
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Selbekk, Rune S.
    Geological relations and U-Pb geochronology of Hyttsjo granites in the Langban-Nordmark area, western Bergslagen, Sweden2007In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 129, no 1, 43-54 p.Article in journal (Refereed)
    Abstract [en]

    The Hyttsjo granites occur in the extensively mineralised Langban-Nordmark area in the westernmost part of the Bergslagen ore province. They have been classified as late Svecokarelian granites due to their homogeneous and generally isotropic appearance in addition to a WR Rb/Sr age. Moreover, they have been considered as possible candidates for supplying essential metals to epigenetic mineralisation in this classic ore district. Two Hyttsjo granites yield U-Pb zircon data ages of 1791 2 and 1793 3 Ma, respectively, which overlap with emplacement ages of the adjacent 1.80-1.78 Ga Filipstad suite belonging to the Transscandinavian Igneous Belt (TIB). Mafic rocks occur quite abundantly associated with the Filipstad-type granite (sensu lato) and various types of mafic enclaves as well as hybrid rocks are present, suggesting a co-magmatic origin. Such mafic intrusives are also exposed in the vicinity of most known Hyttsjo-type plutons. Not least our observations that the former exhibit back-veining by granitic melts suggest intimate causal and temporal relationships between granite formation and mafic TIB rocks. The Hyttsjo granites were probably produced through partial melting related to the intrusion of hot, mafic magmas in and along the border between the TIB and the Svecofennian supracrustal and subvolcanic rocks. Thus, all available observations and data suggest that the Hyttsjo granites are intimately related to and most probable a product of TIB magmatism. Also, they do not lend any support for the hypothesis that the formation of the Hyttsjo granites represent a temporally separate intrusive episode. The Hyttsjo granites are therefore unlikely to be discernibly responsible for specific mineralisation in this area.

  • 8. Hogstrom, Anette E. S.
    et al.
    Sturkell, Erik
    Ebbestad, Jan Ove R.
    Lindström, Maurits
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Ormoe, Jens
    Concentric impact structures in the Palaeozoic of Sweden - the Lockne and Siljan craters2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 1, 65-70 p.Article in journal (Refereed)
    Abstract [en]

    The Ordovician age Lockne and Devonian Siljan craters are two of the largest impact structures in northern Europe. Both formed in targets with a thick, low-strength upper layer. This target configuration is known to generate concentric crater structures with an outer, shallow crater in the low-strength layer, surrounding a central, deeper crater in the more resistant substrate. The concentric craters of Lockne and Siljan are excellent models for studies of similar concentric craters on Earth and elsewhere in the Solar system. Several structural issues remain, and drilling through the craters within the Swedish Deep Drilling Program intends to address the following: the extent of the craters with respect to the time of impact; the effects of cratering on the basement; and the role of basement structure for the crater formation. A problem for the Lockne crater is the relation to the Caledonian orogeny and the lateral extension of the ejecta blanket - the rim is interrupted by a radial depression that has been interpreted both as primary and secondary, tectonically induced. A second feature to study is the deeper and older (1.82-1.80 Ga) NNW-SSE shear zones that cut the basement. In the Siljan area the development of mega block associations comprising the infilling of the graben is disputed. The blocks may either be formed by sagging of peripheral parts of the fault blocks or alternatively by major radial movement involving kilometre long transport.

  • 9. Johnson, Mark D.
    et al.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Casserstedt, Lovise
    Wiborgh, Hanna
    Björck, Svante
    Varved glaciomarine clay in central Sweden before and after the Baltic Ice Lake drainage: a further clue to the drainage events at Mt Billingen2013In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 135, no 3-4, 293-307 p.Article in journal (Refereed)
    Abstract [en]

    Glaciomarine clay found west of Mt Billingen, central Sweden, contains two distinct varve units separated by a sand layer that we interpret to be sediment deposited in the North Sea during the catastrophic drainage of the Baltic Ice Lake (BIL). The lower varve series was deposited proximal to the retreating ice margin and consists of varves that grade upward from gray to red. The upper varve series was deposited after the drainage event when fresh water within the Baltic basin flowed westward north of Billingen; the upper varves grade from red to gray. Grain size, elemental composition (determined by X-ray fluorescence (XRF)), iron and organic-carbon content vary within each varve, with values that grade upward through each varve, but with a sharp contact with the overlying varve. The two varve units differ from each other, with the lower sequence being coarser and the upper containing a higher iron and organic-carbon content. We attribute the differences between pre- and post-drainage varves to reflect changes in distance to the ice margin and provenance. The stratigraphy at the site suggests that the BIL drainage lasted <1 year. Lithostratigraphic correlations to the Lake Langen basin west of Mt Billingen support the idea of glacier ice in the Langen basin during the drainage and a retreat and advance of the ice sheet during Allerod and Younger Dryas, including the possibility of an earlier, Allerod drainage.

  • 10.
    Jonsson, E.
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Billström, K.
    Lead isotope systematics in the Langban deposit and adjacent sulphide mineralisations in western Bergslagen, Sweden2009In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 131, no 3, 215-227 p.Article in journal (Refereed)
    Abstract [en]

    The Langban mines and the investigated sulphide deposits are situated in the westernmost part of the Bergslagen ore province, where it borders the voluminous, younger intrusives of the Transscandinavian igneous belt (TIB) in south-central Sweden. We report thermal ionisation mass spectrometer (TIMS) lead isotope data from the Langban Mn-Fe-(As-Ba-Pb-Sb) deposit and from Pb-Zn-(Cu-Fe-As-Ag) sulphide mineralisations in the region. Based on a systematic study of lead isotopic compositions of minerals from different assemblages and paragenetic stages (galena, native lead, arsenates, arsenites, oxychlorides, silicates, carbonates) from Langban, we propose that c.1.89-1.88Ga (Svecofennian) volcanic-hydrothermal processes supplied the predominating lead component to this complex deposit. Regional amphibolite facies metamorphism, the intrusion of younger granitoids, as well as a succession of ductile to brittle deformation episodes, led to multiple stages of remobilisation of the pre-existing, syngenetic components. During these stages, variable mixing with a minor component of presumed sedimentary origin, comparatively rich in 207Pb and 208Pb, resulted in a temporally unsystematic variability in lead isotopic compositions in the Langban deposit. Contrary to previous suggestions, our lead isotope data suggest that a significant input from, or overprinting by, fluids derived from post-Svecofennian granitic magmatism is unlikely to have affected the Langban mineralisation. By contrast, such processes were probably locally significant in sulphide +/- oxide deposits situated in the immediate vicinity of 1.78Ga intrusives (e.g. at Lahall and northern Myssberget). Here, the lead isotopic compositions of galena are more radiogenic, which is interpreted to be the result of mixing between Svecofennian ore +/- evolved host-rock lead and a later overprinting lead component related to the intrusion of c.1.78Ga granitoids (Filipstad-type TIB, Hyttsjo intrusive suites). Presently, we cannot unambiguously distinguish whether the source of the major overprinting lead component in some of the sulphide mineralisations was derived from the 1.78Ga magmas themselves, or from evolved Svecofennian metasupracrustal whole-rock lead remobilised at that time, although our data lean towards the latter.

  • 11.
    Kumpulainen, Risto A.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Guide for geological nomenclature in Sweden2017In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 139, no 1, 3-20 p.Article in journal (Refereed)
    Abstract [en]

    This guide provides recommendations on how to introduce formal names for geological units, specifically lithostratigraphic, chronostratigraphic, biostratigraphic, lithodemic, tectonic and tectonostratigraphic units, as well as for other geological features such as deformational structures and bedrock landforms. The recommendations apply to Swedish geology but are crafted to harmonize with international practice in geological nomenclature.

  • 12.
    Kumpulainen, Risto A.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bergman, Stefan
    Claesson, Stefan
    Sweden to review its geological nomenclature2017In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 139, no 1, 1-2 p.Article, review/survey (Refereed)
    Abstract [en]

    All geoscientists working with the geology of Sweden are invited to join a common effort to review Swedish geological nomenclature and the naming of geological units and other features. A new guide, the Guide for geological nomenclature in Sweden, provides advice for this review process. The Geological Survey of Sweden will set up a new open and freely accessible database for geological names, and a dedicated name committee with mandate to formally approve proposed names will supervise the naming process. The success of this vital long-term commitment will depend on active participation of the geoscientific community at large.

  • 13.
    Lidmar-Bergström, Karna
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Olvmo, Mats
    Bonow, Johan M.
    The South Swedish Dome: a key structure for identification of peneplains and conclusions on Phanerozoic tectonics of an ancient shield2017In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 139, no 4, 244-259 p.Article in journal (Refereed)
    Abstract [en]

    The relationships between different denudation surfaces/peneplains formed across crystalline basement rocks give valuable information to the tectonic development of ancient shields. The denudation surfaces can be identified by the aid of their landforms, tilt and remnant weathering mantles in relation to cover rocks. Three types of denudation surfaces are identified across south Sweden (1) a tilted flat plain, (2) a tilted hilly surface with relative relief below 150 m and (3) stepped horizontal plains with residual hills. All three types of denudation surfaces are peneplains, denudation surfaces graded to specific base levels. The re-exposed parts of the inclined flat sub-Cambrian peneplain (SCP) extend as a landscape feature from below cover rocks in the north and east and reaches up on the highest summits of the South Swedish Uplands. The SCP (the exact unconformity) is encountered again below Cambrian covers outside the west coast. Thus south Sweden is a geological dome, the South Swedish Dome (SSD), in relation to the Cambrian cover. The southern and western low flanks of the exposed part of the dome are instead characterized by a hilly peneplain, the inclined sub-Cretaceous denudation surface, with remnants of thick, kaolinitic, clayey saprolites. This sub-Cretaceous peneplain is cut off at a distinct level in the south and west by the almost horizontal South Smaland Peneplain, a never covered, epigene, peneplain. The uplift history of the SSD aids to the understanding on the development of late Tertiary drainage systems of the Baltic Basin by the Eridano River.

  • 14.
    O'Regan, Matt
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Greenwood, Sarah L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Preto, Pedro
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Swärd, Henrik
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Geotechnical and sedimentary evidence for thick-grounded ice in southern Lake Vättern during deglaciation2016In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, no 2, 355-366 p.Article in journal (Refereed)
    Abstract [en]

    A 74-meter Late Pleistocene to Holocene sedimentary sequence was recovered from southern Lake Vattern in the autumn of 2012. At approximate to 54m below the lake floor, shear strength and high-resolution bulk density measurements suggest the presence of an unconformity in the varved proglacial clays. Incremental load consolidation tests reveal highly overconsolidated sediments below this level. Preconsolidation pressures for the underlying sediments are between 1250 and 2100kPa, up to approximate to 1700kPa more than the current in-situ effective stress. The highly overconsolidated sediments indicate either substantial erosion (the removal of 215-360m of sediment), or consolidation under a large grounded ice mass sitting up to 230m above paleo-lake level. Glaciotectonic deformation in underlying sediments supports the interpretation of a grounded ice mass. It is likely that this horizon is either contemporaneous with or older than the Levene moraine, formed between 13.4 and 13.8ka. In the approximate to 30m of overlying proglacial clays, there is no further evidence for grounded ice, indicating that any ice advance to southern Lake Vattern during the Younger Dryas would have been limited to an extremely thin ice tongue.

  • 15. Sjoqvist, Axel S. L.
    et al.
    Lindgren, Paula
    Sturkell, Erik F. F.
    Hogmalm, K. Johan
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ivarsson, Magnus
    Lee, Martin R.
    Shock metamorphism and hydrothermal alteration of mafic impact ejecta from the Lockne impact structure, Sweden2017In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 139, no 2, 119-128 p.Article in journal (Refereed)
    Abstract [en]

    The local geology at Kloxasen is characterised by ejecta deposits from the 458 Ma Lockne marine impact. The Kloxasen ejecta are located on a Caledonian parautochthonous unit, approximately 7 km from the centre of the 7.5-km-wide Lockne crater structure. The ejecta were deposited on the seafloor and were covered with seawater immediately after the impact event. Of special interest is a mafic impact breccia within the ejecta, which before the impact was angstrom sby dolerite that belongs to the Jamtland suite of the 1.25 Ga Central Scandinavian Dolerite Group. The mafic impact breccia occurs mainly as a coherent thin domain within a larger block of granitic breccia, which we interpret as a result of the in situ brecciation of a dolerite sill within granitic bedrock. Shock pressure in the doleritic breccia was low, in the order of 0.4 GPa, constrained by the presence of mechanically twinned clinopyroxene. Low shock pressure and brecciation corresponds well to the spall zone of an impact crater, where ejecta originate from. Whereas spalled ejecta can also show signs of having been exposed to high shock pressures, including shocked quartz, evidence for this was not found in the Kloxasen ejecta. The breccia has been hydrothermally altered, but the ejecta are too far removed from the crater to have been affected by hydrothermal circulation in relation to Lockne's impact event. Fluid inclusion analyses suggest that most of the alteration happened later, during the Caledonian orogeny. Geochemical analyses reflect observed mineral alterations well, such as serpentinisation of olivine.

  • 16.
    Swärd, Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    O'Regan, Matt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ampel, Linda
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Ananyev, Roman
    Chernykh, Denis
    Flodén, Tom
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Greenwood, Sarah L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Mörth, Carl Magnus
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Preto, Pedro
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Regional deglaciation and postglacial lake development as reflected in a 74m sedimentary record from Lake Vättern, southern Sweden2016In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 138, no 2, 336-354 p.Article in journal (Refereed)
    Abstract [en]

    The withdrawal of the Late Weichselian ice sheet and rapid isostatic uplift in southern Scandinavia led to the entrainment of large volumes of melt water within the proglacial Baltic Ice Lake (BIL). The eventual western outpost of BIL, Lake Vattern, has been a focal point for studying the dynamic retreat history of the Late Weichselian ice sheet in south central Sweden. This part of the deglacial history is described from an abundance of terrestrial studies, but, to date, no complimentary long sediment cores from Lake Vattern have been available. Here, we present the results from a unique, 74m borehole in southern Lake Vattern that recovered a Late Pleistocene to Holocene sedimentary sequence. Physical and chemical analyses of the sediment and pore water, together with geophysical mapping, reveal glacial as well as postglacial imprints implying an oscillating ice sheet margin, evidence for neotectonic activity and one or more marine incursions into the lake during deglaciation. We attribute the glaciotectonic deformation of the sediments at 54m below the lake floor to an ice readvance that likely occurred at the same time or before the advance that formed the Levene moraine (approximate to 13.8-13.4cal.kaBP). After this event, potential readvances were likely restricted to a more northerly position in the basin. We identify the final drainage of the BIL, but find evidence for an earlier marine incursion into the Vattern basin (approximate to 13.0cal.kaBP), indicating water exchange between the North Atlantic and the Baltic Ice Lake during the late Allerod.

  • 17. Uchman, Alfred
    et al.
    Kumpulainen, Risto A.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Trace fossils in Quaternary glacial varved clays near Uppsala, Sweden2011In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 133, no 3-4, 135-140 p.Article in journal (Refereed)
    Abstract [en]

    Trace fossils Broomichnium cf. fliri, Glaciichnium cf. liebegastensis, Planolites isp., ? Undichna isp. and ? Warvichnium ulbrichi have been recognised in early Holocene glacial varved clays near Vittinge, west of Uppsala, Sweden. They are referred to different arthropods and fishes that periodically colonised the lake floor and were important components of the ecosystem. The trace fossils are typical of the Glaciichnium ichnocoenosis within the Mermia ichnofacies, which suggests less stressful conditions in Vittinge than in many other Quaternary varved clays in Europe typified by the Cochlichnus ichnocoenosis.

  • 18.
    Wastegård, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Andersson, Sofia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hohl Perkins, Veronica
    A new mid-Holocene tephra in central Sweden2009In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 131, no 4, 293-297 p.Article in journal (Refereed)
    Abstract [en]

    A mid Holocene tephra, LBA-2 has been found in a peat bog in central Sweden. Geochemical analyses suggest an origin in an evolved volcanic centre, most likely the Snæfellsnes volcanic centre in western Iceland. The geochemistry of the LBA-2 tephra is similar to the youngest of three silicic tephra layers from Snæfellsjökull, Sn-1 dated to 1780 cal yr BP. However, wiggle-match dating indicates an age of 3550-3650 cal yr BP, close in age to the Hekla-S/Kebister tephra (3720 cal yr BP), previously found in several sites in Scandinavia. Detailed geochemical analyses and dating is lacking for the mid Holocene Sn-2 tephra in Iceland but it is likely that the geochemical composition is similar as the Sn-1 tephra. The LBA-2 tephra is tentatively correlated with the Sn-2 tephra and we also suggest that the ‘x’ tephra layer (ca 3500 BP) found in the Dyngjufjöll area, central Iceland (Sigvaldason et al. 1992) can be correlated with the Sn-2 tephra.

1 - 18 of 18
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf