The ice-rafting history in the Norwegian-Greenland Sea for the last two glacial/interglacial cycles

Using a variety of techniques including microscopic grain lithotype analysis, factor analysis, sediment pellet occurrence analysis and mapping, the distribution of coarse-grained ice-rafted material (IRD) in the Norwegian-Greenland Sea (NGS) was investigated for the last two glacial/interglacial cycles (Oxygen Isotope Stages 6+5 and 2+1). This IRD can be classified into three lithotypes: that dominated by quartz (QZF), that dominated by dark siltstones (DSF) and that dominated by biogenic material (BMF). The DSF predominated in NGS cores from Stage 6 and is thus a 'glacial' facies. The main source for the DSF lies east of Svalbard; additional sources are the Norwegian continental shelf and northeastern Greenland. The QZF predominated the IRD in Stages 5, 2 and 1; because the Weichselian (Stage 2) glaciation was much weaker than the Saale (Sage 6) glaciation, the QZF is considered to be a 'deglacial' and 'interglacial' facies. Because the QZF consists of broken-down crystalline rocks, source areas could lie anywhere in the Arctic realm. A peak in the deposition of dark siltstones or of quartz in the NGS generally occurs <1000 years before the deposition of Heinrich layers further south in the North Atlantic Ocean. This, coupled with the fact that accumulation rates at the times of deposition of the Heinrich facies are generally inceasing or high, indicates that there is a possibility that sudden glacier surges and resulting iceberg calving events from the Scandinavian Ice Sheet occurred within 1000 years of those from the Laurentide Ice Sheet. (orig.)SIGLEAvailable from TIB Hannover: RO 4719(50) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman