Mineral associations of late Quaternary permafrost deposits - Bol’shoy Lyakhovsky Island compared to other locations in northern Siberia.

• Main Authors: Schirrmeister, Lutz, Wetterich, Sebastian, Schwamborn, Georg, Matthes, Heidrun, Grosse, Guido, Klimova, I., Kunitsky, Viktor V., Siegert, Christine
• Format: Conference Object
• Language: unknown
• Published: Melnikov Permafrost Institute (MPI) 2020
• Subjects: Ice; permafrost; Yakutsk; Siberia
• Online Access: https://epic.awi.de/id/eprint/53064/; https://epic.awi.de/id/eprint/53064/1/Schirrmeister_et_al_2020.pdf; https://hdl.handle.net/10013/epic.9b0227d9-1103-402c-93a8-85f2812abc57

Bol’shoy Lyakhovsky Island has been a major focus area in Yedoma research in course of joint Russian-German expeditions in 1999, 2007 and 2014 conducted by colleagues from the Mel’nikov Permafrost Institute Yakutsk and the Alfred Wegener Institute Potsdam [1,2]. However, origins and genesis of periglacial deposits such as the late Pleistocene Yedoma Ice Complex are still debated [3] and referred to by some researchers as pure windblown sediments, while other researchers suggest more local sediment sources from intense nivation and periglacial weathering, or even a polygenetic origin under comparable cold-climatic, highly continental conditions in different regions. To disentangle sources and potential transport pathways of sediments, mineral associations are useful indicators. Identifying linkages of mineral associations in sediments to local bedrock, fluvial sources, or fare ranging sources for potential eolian transport are therefore important. Various studies on palaeoecology [4,5], stable isotopy [6], geophysics [7], biogeochemistry [8] and palaeogenetics [9] have been carried out over the last more than 20 years. In the present study, we analyzed the mineral associations in sediments of one of the best-dated permafrost sequences including the Yedoma Ice Complex exposed at the southern coast of Bol’shoy Lyakhovsky Island near the Zimov’e River mouth. The permafrost record spans about 200 ka covering the Marine Isotope Stages (MIS) 6 to MIS 1 [10,11,12,13,15], although not continuously. From these deposits, exposed from sea level to about 35 m above sea level, we studied heavy and light minerals of 65 samples from different cryostratigraphic horizons in both the 63-125 µm and the 125-250 µm fractions. The studied mineral grains used are subangular to slightly rounded. The heavy mineral associations are dominated by amphibole, epidote, pyroxene, titanite, ilmenite, garnet, zircon, apatite, and rutile. Leucoxene is found in several samples as well as biotite, chlorite and weathered micas. The light mineral ...