A Holocene pollen record from the Laptev Sea shelf, northern Yakutia

Abstract

Holocene shelf deposits from the Laptev Sea shelf (northern Yakutia) were investigated with palynological means. Data were obtained from a 467-cm-long sediment sequence from the southeastern Laptev Sea (74°30 N/136°00 E). The chronology of the core reaches back to 9.4 calendar years (cal. ka), yielding an average sample resolution of ∼100 years. The temporal changes in pollen and spore spectra of the marine record are primarily the result of variations of transport mechanisms, i.e., the large rivers draining into the shelf sea, the atmospheric circulation, and the coastal erosion. Because of the close land-shelf linkage due to riverine connections, the trends observed in the shelf data seem to be in good agreement with the Holocene vegetational evolution of the coastal hinterland. An enhanced transfer of tree pollen onto the shelf during the middle Holocene began around 7.5 cal. ka and is interpreted as the result of the northernmost occurrence of the treeline between 9 and 3.8 cal. ka. A similar time-coeval accordance between land and shelf pollen records is observed for the late Holocene climatic cooling trend in Arctic Siberia. In the shelf record, this cooling is characterized by increasing abundance of herbaceous pollen that commenced after 2.7 cal. ka, which is about 1 cal. ka later than on land.