Palynomorphs and particulate organic matter in Late Pleistocene–Holocene deep- water sediments in the Nansen Basin (Arctic Ocean): From sources to sink

Abstract

Deep-sea surface clay sediments and ice-dropped clasts collected at 3998 m water depth in the Nansen Basin (88.4⁰N-28.4⁰E) have been examined for palynomorphs and particulate organic matter (POM). Quaternary-Holocene marine palynomorphs and dispersed organic particles are subordinate to pre-Quaternary material and the studied samples contain mostly terrigenous organic matter. Most of the palynomorphs and organic matter are reworked from strata ranging from Late Devonian to late Cenozoic in age. The Quaternary-Holocene marine assemblages contain mostly species with wide thermal tolerances, and only few Arctic to cold-water specimens. This points towards warmer water conditions than today during the time of deposition. Detrital U-Pb geochronology from one ice-dropped clast is compatible with deposition in the Devonian, with a detrital zircon age spectrum characterised by Palaeoproterozoic through Neoproterozoic ages and a youngest peak at c. 400 Ma. The possible provenance areas of most of the reworked POM and ice-dropped clasts in the Nansen Basin are far from the deep-basin sink, including areas on the Siberian Craton drained by the Lena River and other major rivers flowing into the Laptev Sea, as well as areas in the northern Barents Shelf between Svalbard and Severnaya Zemlya, where glacially eroded troughs run into the Nansen Basin.