Climatic variations and sediment provenance during the last 16 000 years in the North Hinlopen Trough, Svalbard

Abstract

Gravity core HH18-1500GC retrieved from the Hinlopen Trough, Arctic Ocean, has been investigated in order to reconstruct the climatic evolution and ocean circulation over the last 16 000 years. The core was taken at the edge of the trough on the northern Svalbard shelf in order to be certain to reach into till, with the intent of dating the retreat of the ice sheet. The Fram Strait is located between Greenland and Svalbard, and is the main gateway for water and heat exchange to the Arctic Ocean. Reconstructing paleoceanography and paleoenvironmental changes in relation to climate change is important to predict future climate changes, as changes occurring in this area probably will affect the whole Arctic. The core was divided into 5 lithological and stratigraphic units based on grain size distribution, magnetic susceptibility, ice-rafted debris data, benthic and planktonic foraminiferal analysis and content of total carbon, total organic carbon and calcium carbonate. An age model was constructed based on AMS-14C dates and correlation with other studies. The core contains sediments from pre-Bølling (> 16 100 cal years BP), the Bølling-Allerød interstadials (16 100 – c. 13 000 cal years BP), the Younger Dryas stadial (c. 13 000 – c. 12 000 cal years BP) and the Holocene (< c. 12 000 cal years). The most recent sediments are c. 6500 cal years BP, indicating erosion or non-deposition due to strong bottom currents activity on the shelf. Five distinct pinkish layers were discovered within the Bølling-Allerød interval, correlating to increasing spectre of lightness, decreasing magnetic susceptibility and decreasing IRD content. Pink sediments were probably derived by melt water run-off from retreating glaciers, under high surface temperatures and at high sedimentation rates.