ARCTIC-OCEAN EVIDENCE FOR LATE QUATERNARY INITIATION OF NORTHERN EURASIAN ICE SHEETS

A high-resolution multiparameter stratigraphy allows the identificatio n of late Quaternary glacial and interglacial cycles in a central Arct ic Ocean sediment core. Distinct sandy layers in the upper part of the otherwise fine-grained sediment core from the Lomonosov Ridge (lat 87 .5 degrees N) correlate to four major glacials since ca. 0.7 Ma. The c omposition of these ice-rafted terrigenous sediments points to a glaci ated northern Siberia as the main source. In contrast, lithic carbonat es derived from North America are also present in older sediments and indicate a northern North American glaciation since at least 2.8 Ma. W e conclude that large-scale northern Siberian glaciation began much la ter than other Northern Hemisphere ice sheets.