Nordic Seas surface ice drift reconstructions: evidence from ice rafted coal fragments during oxygen isotope stage 6

Abstract

Sixteen long sediment cores from the eastern Arctic Ocean, the Fram Strait and the Norwegian-Greenland Sea, documenting 200 000 years of sedimentation, were studied for their qualitative dropstone composition (>500 lain-fraction). In sediments from oxygen isotope stages 1-5, coal particles are usually subordinate components of the coarse fraction. In contrast to younger deposits, coal content in oxygen isotope stage 6 (186-128 ka) varies between 20% and 65% in the eastern Arctic Ocean and the Fram Strait and between 5% and 20% in the Norwegian Sea. Southward decreasing coal content and similarities in maturity and petrography of the coals indicate that the coal was transported by iceberg or sea ice rafting more than 1000 km to the south. It is suggested that during intervals of oxygen-isotope stage 6 drifting ice carried abundant coal fragments from the eastern Arctic Ocean southward through the Fram Strait into the eastern Norwegian Sea. Thus, surface circulation was then opposite to that of today.

Depositional regimes in the Norwegian-Greenland Sea: the last two glacial to interglacial transitions

“…According to their spatial distribution, their temporal frequency and their characteristic sedimentological composition (e.g. the pulse-like increased contents in TOC and temgenous coarse fraction or the abundance of IRD tracer lithologies), differing reconstructions of depositional regimes and ice drift patterns have been proposed (Bischof et al 1990;Henrich 1992). A conflicting circulation model for periods of diamicton deposition is deduced from stable isotope evidence Weinelt et al 1992).…”

“…Based on a southward decreasing trend in coal clast abundance in Isotope Stage 6 deposits of the NGS, the Fram Strait and the eastern Arctic Ocean, Bischof et al (1990) reconstructed a temporary southward ice drift from the Arctic Ocean into central areas of the NGS, as far as the Vering Plateau. Owing to the low thermal maturity of coal dropstones, the postulated source areas were the Franz Josef Land archipelago or the extensive Siberian Shelf.…”

“…For specific glacial time slices Bischof et al (1990) deduce from abundance variations of coal clasts a southward ice drift along the eastern margin of the NGS. In contrast, a northward ice drift along the eastern margin, occasionally reaching as far north as the Fram Strait, is reconstructed from the occurrence of chalk dropstones (Henrich 1990;Hebbeln 1991;Spielhagen 1991).…”

Late Quaternary paleoceanography in the Fram Strait

“…The Fram Strait between Greenland and Svalbard is the most hnportant passage for poleward heat transport and water exchange between the Arctic Ocean and the world ocean [Aagaard and Greisman, 1975 [Morris, 1988;Bischof, 1990;Spielhagen, 1991] and allow a correlation of the marine sequence to the onshore geological record of the glacial history of Svalbard and the Barents Sea of the last 110 kyr [Hebbeln, 1992].…”

Sediment transport to the Laptev Sea–hydrology and geochemistry of the Lena River

“…The sediments supplied by rivers are partly incorporated into sea ice and transported from the Laptev Sea shelf across the Arctic Ocean and through the Fram Strait via the Transpolar drift (Bischof et al 1990;Eggertsson 1994;Stein & Korolev 1994). For that reason the characterisation and quantification of recent sediment transport from the Eurasian continent to the Arctic Ocean and its variations between glacial and interglacial stages reveal important information on the paleoclimate of Eurasia and the history of ice cover and drift patterns in the Arctic Ocean.…”