|
|
|
|
|
|
|
|
HPQ-01 General contributions to Quaternary geology
|
|
|
|
Middle Weichselian glacial event in the central part of the Scandinavian ice sheet recorded in the Hitura pit, Ostrobothnia, Finland
|
|
|
|
Seija Kultti, University of Helsinki (Finland)
Veli-Pekka Salonen, University of Helsinki (Finland)
Anu Kaakinen, University of Helsinki (Finland)
Kari Eskola, Dating Laboratory (Finland)
Arto Miettinen, Norsk Polarinstitutt (Norway)
Juha Pekka Lunkka, University of Oulu (Finland)
|
|
|
|
Central Ostrobothnia, Finland, is centrally located in relation to the Scandinavian Ice Sheet, and glacial erosion has been relatively weak. The Hitura sequence was investigated using a combination of litho-, bio- and chronostratigraphical data to reconstruct the extent and iceflow pattern during the Middle Weichselian Glaciation (MWG). The results indicate that the sediment succession represents two entire glacial advance and retreat cycles. The lowermost deposits are late Saalian esker and delta sediments overlain by sediments that correlate with the early Eemian lacustrine phase. Remnants of the Eemian soil post-dating the lacustrine phase were also observed. The area was ice-free during the entire early Weichselian (EWG). The first glacial advance recorded in the sediments is related to MWG. It took place after 79 yr ago, and it deformed underlying sediments, and deposited an immature till including large detached sediment pods with remains of organic material, soils and fluvial sediments representing allochthonous material from EWG ice-free stadials and interstadials. The glacial deposits are conformably overlain by glaciolacustrine and littoral accumulations indicating MWG deglaciation between 62 to 55 kyr ago. Based on the till fabric measurements from the till unit overlying the MWG sediments, ice advance during the Late Weichselian (LWG) was initially from the westerly and then north-northwesterly direction.
|
|
|
|
|
|
|
|
|
