Ice Complex deposits, or so-called Yedoma formations, are widely distributed in the North Siberian coastal lowlands. These terrestrial accumulations of up to several 10 m thickness are usually characterised by fine to medium grained clastic sediments (silt or silty loam with layers of sand), a very high ground ice content, and high total organic carbon (TOC) contents (2-4%, in some layers of buried soils up to 16%). Ground ice contents can be up to 90%, including large ice wedges, and segregated ground ice in the form of small ice lenses and ice bands. Accumulated during the Late Pleistocene glacial period (Zyryan, Kargin, and Sartan; MIS 4-2), the Ice Complex is a rich palaeoenvironmental archive for this period with excellent preservation conditions for organic plant and animal remains. The Ice Complex formed under various facies regimes, indicating its dependence from cold-climatic continental conditions rather than sedimentary processes alone (nival, proluvial, fluvial, alluvial, aeolian). Permafrost degradation by thermokarst and thermo-erosion in the Yedoma regions appears to be a major agent in the partial transformation of the TOC stored in the ice-rich Ice Complex into greenhouse gases. Therefore, the Ice Complex is an important compartment of the terrestrial carbon cycle. To evaluate the past and possible future impacts of permafrost degradation on the Ice Complex and resulting matter fluxes, the quantification of sediment, ground ice content, and TOC content of the Ice Complex is an important task. We use field data, remote sensing, and terrain modelling within a geographical information system (GIS) environment to quantify these essential parameters of Ice Complex deposits for a variety of sites in the Laptev Sea region. Field data consists of Ice Complex distribution, thickness, ice content, and TOC, and was collected within several Russian and joint Russian-German expeditions during the last years. Remote sensing was applied for the mapping of Yedoma extent and distribution of thermokarst and thermo-erosion surface features. We quantified the volume of Ice Complex deposits with terrain modelling based on digital elevation models, stratigraphical information, the collected field data, and our mapping results. Finally, we highlight some implications for mass balance calculations of the Yedoma formation in Siberia and possible feedbacks of Ice Complex accumulation and permafrost degradation by thermokarst with the terrestrial carbon cycle.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL7-From permafrost to deep sea in the Arctic