A biomarker-based paleoclimatic reconstruction of MIS1, MIS3 and MIS5e based on permafrost deposits from NE Siberia

• Main Authors: Martens, Jannik, Kusch, Stephanie, Winterfeld, Maria, Mollenhauer, Gesine, Schwamborn, Georg, Schirrmeister, Lutz, Wetterich, Sebastian, Overduin, Paul, Rethemeyer, Janet
• Format: Conference Object
• Language: unknown
• Published: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research International Permafrost Association 2016
• Subjects: permafrost; Siberia
• Online Access: https://epic.awi.de/id/eprint/42022/; https://hdl.handle.net/10013/epic.48817

Understanding long-term environmental dynamics is crucial to elucidate recent and predict future feedback processes of permafrost in a changing environment. Northeastern Siberia is a key site to study organic matter (OM) that has been formed during the Pleistocene. This OM contains information about past vegetation, environment, and organismic communities,thus, offering the potential to understand environmental change of Arctic Russia on glacial and interglacial timescales. We analyzed five permafrost cores from Bol’shoy Lyakhovsky Island and the Buor Khaya Peninsula to study the environmental history of Northeastern Siberia for the past 130 kyr (MIS1, MIS3, and MIS5e) using molecular and isotopic tools. We present a comprehensive biomarker data set including terrestrial vascular plant biomarkers such as n-alkanes, n-fatty acids, and lignin phenols. In addition, we analyzed bacterial and archaeal membrane lipids including branched and isoprenoid glycerol dialkyl glycerol tetraethers (brGDGTs and isoGDGTs) and bacteriohopanepolyols (BHPs) from which environmental properties including mean annual air temperatures (MAAT) and pH, and bacterial taxonomic information can be constrained. Initial results show that MAATs as determined using brGDGTs were on average higher during MIS3 than MIS1 on both Bol’shoy Lyakhovsky Island and the Buor Khaya Peninsula. Higher MAATs during MIS3 are accompanied by lower BIT indices (based on brGDGTs and isoGDGTs) indicating relatively higher in-situ archaeal production than during MIS1 when bacteria dominate and soil pH is lower. On Bol’shoy Lyakhovsky Island vascular plant-derived, high molecular weight (HMW) n-alkanes are also more abundant in the MIS1 deposits than the MIS3 deposits and co-vary with low pH and low MAAT while the opposite trend is observed for the Buor Khaya Peninsula deposits. HMW n-alkanes characteristic for Poaceae and Cyperaceae dominate the n-alkane assemblages during warm stages, while n-alkanes typical for the moss Hylocomium are less abundant indicating the ...