Filling a White Spot on the Yedoma Map: the Baldwin Peninsula, West Alaska

• Main Authors: Strauss, Jens, Grosse, Guido, Jongejans, Loeka L., Jones, Benjamin M., Fuchs, Matthias, Nitze, Ingmar, Laboor, Sebastian, Lenz, Josefine
• Format: Conference Object
• Language: unknown
• Published: 2017
• Subjects: Bering Land Bridge; Chukchi; Chukchi Sea; Ice; permafrost; Seward Peninsula; Thermokarst; wedge*; Alaska; Siberia; Yukon
• Online Access: https://epic.awi.de/id/eprint/45150/; https://epic.awi.de/id/eprint/45150/1/ACOP2017_Strauss_abstract.pdf; https://hdl.handle.net/10013/epic.51331; https://hdl.handle.net/10013/epic.51331.d001

Vast regions of Arctic Siberia, Alaska and the Yukon are covered with ice-rich silts penetrated by large ice wedges, resulting from syngenetic sedimentation and freezing during the Pleistocene. These deposits are termed yedoma permafrost. Because of rapid incorporation of organic material into permafrost during sedimentation, yedoma deposits are expected to store poorly degraded organic matter. The total amount of organic carbon in the yedoma region is estimated to be approx. 400 gigatons. As a consequence of the high ground ice content, yedoma deposits are especially prone to degradation triggered by climate changes and/or human activity. When yedoma deposits degrade, large amounts of previously sequestered carbon as well as nutrients will be released which is of global significance for the climate system. Following on the tracks of permafrost pioneer David M. Hopkins, who studied this region during his conceptualization of the Bering Land Bridge in the 1950/60s (Hopkins et al. 1959, 1962), we conducted a field campaign to the Baldwin Peninsula in West Alaska. Based at the town of Kotzebue, one of the aims of this expedition was to describe yedoma landscapes and start a carbon inventory of this previously undocumented part of yedoma. The intention was to search for and characterize yedoma deposits whose presence was inferred from landscape morphometrics typical for yedoma (deep thermokarst lake basins, multiple overlapping lake basin generations, rolling hills with uplands where small deep thermokarst ponds are found, steep erosion margins along lake and coastal shores) on the neighboring Seward Peninsula and in Siberia as identified in remote sensing imagery. We were able to identify several yedoma upland exposures eroded by the Chukchi Sea on the western shore of the Baldwin Peninsula. We found clear evidence of yedoma permafrost occurrence at Cape Blossom, 20 km south of Kotzebue. We used a cryostratigraphical approach to sample yedoma and drained thaw lake basin exposures at this site. Moreover, different ...