Glacial geology and palaeo-ice dynamics of two ice-sheet margins, Taymyr Peninsula, Siberia and Jameson Land, East Greenland

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)


title = "Glacial geology and palaeo-ice dynamics of two ice-sheet margins, Taymyr Peninsula, Siberia and Jameson Land, East Greenland",
abstract = "The North Taymyr ice-marginal zone (NTZ) on the Taymyr Peninsula, Arctic Siberia and the Ugleelv Valley on Jameson Land, East Greenland, have been investigated with the aim of reconstructing the glacial history, including depositional processes and environments. Geomorphological, sedimentological, stratigraphical and remote sensing methods have been combined to give a comprehensive view of developments in the two areas. Optically stimulated luminescence (OSL) and radiocarbon (14C) dates provide the chronological control. The Kara Sea shelf was glaciated three times during the Weichselian, each time with a smaller ice cover than before. The ice sheets caused a reversal of the fluvial drainage towards the south on the Taymyr Peninsula and, during the Early-Middle Weichselian, also the damming of proglacial lakes. The youngest ice-advance, but probably also the older ones, was warm-based and 'surge-like'. After it had reached its maximum position, the margin froze to its base and compressional flow took place there. The North Taymyr ice-marginal zone (NTZ) was initiated during an Early Weichselian retreat stage (c. 80 ka BP) and added to during the Middle (c. 65 ka BP) and Late Weichselian (<20 ka BP) ice advances, thus revealing a complex history. It comprises ice-marginal and supraglacial landsystems dominated by 2-3 km wide thrust-block moraines. Large areas are still underlain by remnant glacier ice and a supraglacial landscape with numerous ice-walled lakes and kames is forming even today. The proglacial landsystem is characterised by subaqueous or terrestrial environments, depending on altitude and time of formation. The sedimentary succession in the Ugleelv area comprises three tills, glaciolacustrine, glaciofluvial and aeolian sediments. The depositional history started in the early Saalian with a prograding delta in a lake dammed by an outlet glacier in Scoresby Sund. Soon thereafter, and also once during the Weichselian, Jameson Land was inundated by glaciers emanating from Liverpool Land in the east. These glaciers were warm-based and deposited glaciofluvial sediments, local tills and small end moraines. Conditions were less dynamic later in the glacial cycles. During most of the Weichselian the Ugleelv area was ice free and aeolian activity took place, but in the late Saalian the Greenland ice sheet expanded eastwards over the area. This ice was mainly cold-based but in places temporarily warm-based, where a lodgement till was deposited. During deglaciation there was substantial glaciofluvial erosion. The Kara Sea ice sheet and the Greenland ice sheet behave differently through a glacial cycle. The shelf-centred Kara Sea ice experiences large shifts in areal extent and disappears completely during interglacials. 'Individual' ice advances seem to be gover-ned by internal ice dynamics rather than by climatic changes. Contrary to this, the Greenland ice sheet is relatively stable and the climatically driven expansion or retreat of its outlet glaciers through the fjords represents the major changes.",
keywords = "ice dynamics, Pleistocene, Arctic Siberia, East Greenland, Sedimentology, Physical geography, Sedimentologi, pedology, geomorphology, klimatologi, kartografi, markl{\"a}ra, geomorfologi, cartography, Fysisk geografi, ice-marginal processes, glacial history, climatology",
author = "Helena Alexanderson",
note = "Defence details Date: 2002-10-25 Time: 13:15 Place: room 308, S{\"o}lvegatan 13, Lund External reviewer(s) Name: Landvik, Jon Title: Prof. Affiliation: Norges landbruksh{\o}gskole, Norway --- Article: I: Alexanderson, J.H. 2000: Landsat mapping of ice-marginal features on the Taymyr Peninsula, Siberia – image interpretation versus geological reality. Geological Quarterly 44(1), 15-25. Article: II: Alexanderson, H., Hjort, C., M{\"o}ller, P., Antonov, O. & Pavlov, M. 2001: The North Taymyr ice-marginal zone, Arctic Siberia – a preliminary overview and dating. Global and Planetary Change 31(1-4), 427-445. Article: III: Alexanderson, H., Adrielsson, L., Hjort, C., M{\"o}ller, P., Antonov, O., Eriksson, S. & Pavlov, M. 2002: Depositional history of the North Taymyr ice-marginal zone, Siberia – a landsystem approach. Journal of Quaternary Science 17(4), 361-382. Article: IV: Adrielsson, L. & Alexanderson, H.: Two cycles of ice-sheet and coastal mountain glaciation in central East Greenland. Manuscript submitted to Boreas.",
year = "2002",
language = "English",
isbn = "91-86746-48-0",
series = "Lundqua thesis",
publisher = "Quaternary Sciences, Department of Geology, Lund University",
number = "48",
school = "Quaternary Sciences",