Influence of Holocene thermokarst activities on mineral element content in Yedoma deposits

• Main Authors: Monhonval, Arthur, Opfergelt, Sophie, Mauclet, Elisabeth, Hirst, Catherine, Strauss Jens, Grosse Guido, Schirmeister Lutz, Kuhry Peter, Artic Week
• Other Authors: UCL - SST/ELI/ELIE - Environmental Sciences
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: Yedoma; Alas; Thermokarst; thawing permafrost; mineral element; Ice; permafrost; Siberia
• Online Access: http://hdl.handle.net/2078.1/224223

Ice-rich permafrost deposits such as Yedoma are highly sensitive to thaw. Given that they contain up to one third of the organic carbon content of the Northern circumpolar permafrost region, their degradation is considered a potential climate tipping point on Earth due to the potential release of greenhouse gases. These deposits are particularly vulnerable to disturbances such as thermokarst and thermo-erosion processes. Such disturbances occurred during the Holocene leading to the formation of alas (drained thermokarst lake basin) in Yedoma regions. With thermokarst processes, Yedoma degradation exposes deeper materials that have not been subjected to liquid water for thousands of years. Those deeper materials are composed of organic carbon but also mineral constituents. The exposure of these constituents may modify the associations between organic carbon and minerals. To more accurately predict the fate of organic carbon from Yedoma upon thawing, it is required to assess local variability of their mineral element content in a context of Yedoma and alas. Based on deep Yedoma permafrost samples from Siberia (Kytalyk, BuorKhaya, Sobo Sise) from the Late Pleistocene until the early Holocene (55 000 - 8000 yr BP), this study provides evidence for changes in total content in Ca, Al and Fe between Yedoma and alas deposits. It is hypothesized that thermokarst disturbance affects mineral element distribution and might therefore affect the mineral elements available to form associations with organic carbon.