GLACIOTECTONICS INDICATE SOUTHERLY FLOW DIRECTIONS ON TAYMYR, SIBERIA

The growth of the Kara Sea Ice Sheet (KSIS) during repeated glacial cycles was initiated by the expansion of local ice caps around the Kara Sea. Later, these ice caps merged on the shallow shelf and grew and behaved as an ice sheet. This ice sheet flowed to the north onto the Severnaya Zemlya archipelago and to the south across the Byrranga Mountains on the Taymyr Peninsula. Prominent moraine ridge complexes – <15 km wide, 100-150 m high, and >100 km long – now represent either terminal positions of different KSIS stages or halts in retreat from maximum positions during overall recession. Some ridges form distinct morainal loops while others are more diffuse. North of the Byrranga Mts., there is a moraine ridge that has a complex structure resulting from the Early Weichselian ice recession, Middle Weichselian ice expansion, and Late Weichselian ice advance. South of the Byrranga Mountains, eight moraine ridges have been documented and identified on Landsat satellite images and associated Digital Elevation Models. However, the age of those moraines is poorly constrained and their structure is inadequately understood. Preliminary results from structural measurements of till and glaciotectonized sediments adjacent to the Severokokorsk moraine indicate ice flow from southerly directions at some stage. There are two working hypotheses to explain this; a) the glaciotectonics reveal local ice flow in the marginal zone of the Kara Sea Ice Sheet which had an overall flow from the north, or b) the glaciotectonics suggest a large Putorana Ice Sheet with ice flow from the south that, perhaps, in a later stage was overtaken by the Kara Sea Ice Sheet coming from the north.

Samples of sediments, mollusks, and organic matter were collected for dating (¹⁴C, OSL, ESR) and analysis of sedimentary environments and marine fauna. Samples of erratics sitting on top of the ridges were collected for radionuclide exposure dating (³⁶Cl). Currently, most samples are “stuck” in Russia due to bureaucratic problems but are anticipated to arrive to Sweden in late 2011. However, 18 radiocarbon datings on shells and organic remains from marine sediments incorporated into the glaciotectonics give ages in excess of 48 kyr (i.e. infinite ages), thus suggesting that all tectonics are of pre LGM age, as expected.