Deglacial to Holocene biomarker records of terrigenous input and sea surface temperature in the NW Pacific and the western Bering Sea

• Main Authors: Meyer, Vera, Tiedemann, Ralf, Max, Lars, Hefter, Jens, Schefuß, Enno, Mollenhauer, Gesine
• Format: Conference Object
• Language: unknown
• Published: 2014
• Subjects: Bering Sea; Greenland; Greenland ice core; Ice; ice core; Kamchatka; Kamchatka Peninsula; permafrost; Siberia
• Online Access: https://epic.awi.de/id/eprint/41853/; https://hdl.handle.net/10013/epic.48683

Polar regions are strongly affected by global climate change since warming is projected to be strongest in high latitudes. Understanding temperature changes is crucial to unravel the impact of climate change there. Rising sea surface temperatures (SST) modify oceanographic conditions of the polar and subpolar seas. In the northern hemisphere, increasing mean annual air temperatures (MAAT) lead to thawing of permafrost soils which may initiate release of vast amounts of fossil carbon to the environment. In order to study changes in SST, MAAT and the intensity of carbon export from East Siberia to the adjacent NW Pacific and Bering Sea over the last deglaciation we analyzed terrigenous and marine biomarkers (n-alkanes, branched GDGT & isoprenoid GDGTs) from two sediment cores recovered at the continental margin off Kamchatka peninsula (NW Pacific), and from the western Bering Sea. We test the applicability of TEX86 as a tool for SST-reconstructions over the last deglaciation and thereby produce a TEX86 based SST-record in the Bering Sea. The results are compared to Uk’37 and Mg/Ca based SST. The TEX86 record is interpreted to reflect summer subsurface temperatures. We further investigate the CBT/MBT indices calculated from the branched GDGTs as well as δD of n-alkanes as tools for the reconstruction of MAAT. MAAT based on CBT/MBT shows a pattern similar to Greenland ice core temperature records with cooling events during the Heinrich Event 1 (HE1) and the Younger Dryas (YD). The results for the late Holocene match the modern MAAT of Kamchatka peninsula. However, from the Last Glacial Maximum to the onset of the Bølling/Allerød interstadial (B/A) CBT/MBT produces unrealistic temperatures that are as high as during Holocene. Possibly the record shows summer temperatures during LGM and the early deglaciation and reflects the annual mean at the beginning of the B/A. When interpreting these findings one has to keep in mind that concentrations of branched GDGT are very low (BIT lower than 0.1). Thus it is ...