Structure, Composition, and Origin of the Yedoma Suite around the Laptev Sea

• Main Authors: Schirrmeister, Lutz, Wetterich, Sebastian, Grosse, Guido, Siegert, Christine, Kunitsky, V.
• Format: Conference Object
• Language: unknown
• Published: 2007
• Subjects: East Siberian Sea; Ice; laptev; Laptev Sea; lena river; permafrost; wedge*; Siberia
• Online Access: https://epic.awi.de/id/eprint/17043/; https://hdl.handle.net/10013/epic.26864

Yedoma, consisting of so-called Late Pleistocene Ice Complex deposits, is a special type of permafrost formation widely distributed in Northeast Siberia, especially in the coastal lowlands of the Laptev and the East Siberian Sea as well as on the New Siberian Archipelago. Its most impressive characteristics is the supersaturation with segregated ground ice in the deposits (gravimetric ice content 40 to 250 wt %), the occurrence of huge ice wedges, and its total deposit thickness of 10 to 60 m. A wide variety of hypotheses for the genesis of these deposits were developed in the past decades. Our study, based on eight years of intensive investigations of Yedoma exposures within joint German-Russian expeditions along the Laptev Sea coast, in the Lena River Delta, and on the New Siberian Archipelago, provides the first integrated study of a wide variety of Ice Complex sequences in this region and new insights into their genesis. Yedoma sequences consist of several buried palaeo-soils of different maturity formed within a polygonal landscape. Variations in organic carbon contents (1 to 25 wt %) as well as numerous datasets of palaeo-environmental proxies reflect changing environmental conditions during the period of Yedoma formation. Based on heavy mineral analyses, the clastic sediment material mainly originated from nearby located mountain ridges or rocky hills. Accumulation of the Yedoma Suite occurred as the result of a complete transformation of the hydrological regime proved by the consistent occurrence of fluvial sand deposits below Yedoma horizons, dated between 50 to 100 ky by Optical Stimulated Luminescence and U/Th methods. The fluvial dominated hydrological regime shifted to an irregular runoff from the mountain and hill areas fed by highly a seasonal runoff from perennial snowfields. This runoff occurred over less-inclined, poorly drained plains in the Laptev Sea shelf lowland in front of the mountains. The highly seasonal runoff from these snowfields delivered clastic material from nival-eolian and ...