Lutz Schirrmeister

Paleoenvironmental and paleoclimatic records from permafrost deposits in the Arctic region of Northern Siberia

Ice Complexes, extremely ice-rich permafrost deposits with large ice wedges, are widely distributed in the Arctic region of northeast Siberia. They present excellent archives for the reconstruction of Late Quaternary paleoenvironmental conditions in nonglaciated areas. In 1998, 1999, and 2000 Russian and German scientists worked together on the Bykovsky Peninsula southeast of the Lena Delta in order to investigate the Ice Complex and its associated sediments. Intensive cryolithological and sedimentological studies, Radiocarbon age determinations, paleobotanical studies, micropaleontological investigations, studies of mammal and insect fossils, and stable isotope analyses of ground ice were performed. Radiocarbon data have been obtained from the entire exposed sequence coveringapproximately the last 60,000 years. The results indicate that compared with modern time the investig ated Ice Complex sequence was formed duringtwo cooler and more arid stages of the Late Pleistocene with relatively uniform environmental conditions, separated by a stage with environmental variations and more intensive soil formation caused by climate amelioration. The Late Pleistocene environmental changes were not as strong as those occurring during the Pleistocene/Holocene transition where a sharp break is evident. r 2002 Elsevier Science Ltd and INQUA. All rights reserved.

Modern terrigenous organic carbon input to the Arctic Ocean

The main objective of this chapter is to assess recent fluxes of terrigenous dissolved and particulate organic carbon into the Arctic Ocean. The most important terrigenous sources of organic matter (OM) in the ocean are (1) river and groundwater discharge, (2) coastal erosion, (3) sea-ice input and (4) aeolian material fluxes. The organic carbon fluxes of each of these pathways will be considered separately and a evaluation will be made of their roles in the total balance of OM input to the ocean.

The deep permafrost carbon pool of the Yedoma region in Siberia and Alaska

[1] Estimates for circumpolar permafrost organic carbon (OC) storage suggest that this pool contains twice the amount of current atmospheric carbon. The Yedoma region sequestered substantial quantities of OC and is unique because its deep OC, which was incorporated into permafrost during ice age conditions. Rapid inclusion of labile organic matter into permafrost halted decomposition and resulted in a deep long-term sink. We show that the deep frozen OC in the Yedoma region consists of two distinct major subreservoirs: Yedoma deposits (late Pleistocene ice- and organic-rich silty sediments) and deposits formed in thaw-lake basins (generalized as thermokarst deposits). We quantified the OC pool based on field data and extrapolation using geospatial data sets to 83 + 61/−57 Gt for Yedoma deposits and to 128 + 99/−96 Gt for thermokarst deposits. The total Yedoma region 211 + 160/−153 Gt is a substantial amount of thaw-vulnerable OC that must be accounted for in global models.

Deposition and degradation of a volatile‐rich layer in Utopia Planitia and implications for climate history on Mars

[1] We investigate the surface morphology of a study area in western Utopia Planitia, Mars, which is characterized by a variety of landforms that resemble those of terrestrial periglacial landscapes. Polygonally fractured ground and thermokarst-like depressions are found to be located in a young mantling deposit with a thickness of several tens of meters. We observe a latitudinal dependence of the degradation of this mantling deposit. Larger depressions, whose floors reveal the underlying basement rocks, cover a higher fraction of the total terrain in the southern part of the study area than in the northern part, indicating a more intense degradation of the mantle in the south. All depressions have an asymmetric cross section in north-south direction, interpreted to be the result of the different solar radiation on differently oriented slopes. On the basis of our morphological observations, we develop a conceptual model for landscape evolution in western Utopia Planitia. It involves subaerial deposition of a layered, ice-rich mantle and its subsequent degradation by polygon formation and sublimation. A terrestrial analog to the polygonally fractured mantling deposit and its thermokarst-like depressions is the Siberian Ice Complex or ‘‘Yedoma,’’ which consists of subaerial ice-rich deposits and is connected to nonglaciated landscapes with highly continental cold-climatic environmental conditions. Our comparison suggests that no unusual or exotic processes need to be invoked to explain the current morphology of western Utopia. However, the young age of the deposition and degradation implies climatic excursions in the very recent past on Mars.

Late Quaternary History of the Accumulation Plain North of the Chekanovsky Ridge (Lena Delta, Russia): A Multidisciplinary Approach

Permafrost deposits were studied along the Olenyeksky and the Arinsky distributaries in the western Lena delta using a multidisciplinary approach that included sedimentological, mineralogical, stable-isotope, and paleoecological analyses in order to reconstruct the Late Quaternary landscape and environmental history of this Northeast

Grain‐size properties and organic‐carbon stock of Yedoma Ice Complex permafrost from the Kolyma lowland, northeastern Siberia

The organic carbon stock in permafrost is of increasing interest in environmental research, because during the late Quaternary a large pool of organic carbon accumulated in the sedimentary deposits of arctic permafrost. Because of its potential to degrade and release organic carbon, the organic-matter inventory of Yedoma Ice Complex deposits is relevant to current concerns about the effects of global warming. In this context, it is essential to improve the understanding of preserved carbon quantities and characteristics. The paper aims to clarify the Yedoma Ice Complex origin, and to develop an approach for volumetric organic-matter quantification. Therefore, we analyzed the grain size and the organic-matter characteristics of the deposits exposed at the stratigraphic key site Duvanny Yar (lower Kolyma River, northeast Siberia). A distinct bimodal grain-size distribution confirms a polygenetic origin of the frozen sediments from a flood-plain environment. The total organic-carbon content averages 1.5 ± 1.4 wt% while the volumetric organic-carbon content averages 14 ± 8 kg/m³. However, large-scale extrapolations for Yedoma Ice Complex deposits in general are not reasonable yet because of their rather unclear spatial distribution. We conclude that Yedoma Ice Complex formation at Duvanny Yar was dominated by water-related (alluvial/fluvial/lacustrine) as well as aeolian processes. The total organic-carbon content of the studied deposits is low if compared to other profiles, but it is still a significant pool.

Periglacial landscape evolution and environmental changes of Arctic lowland areas for the last 60 000 years (western Laptev Sea coast, Cape Mamontov Klyk)

Non-glaciated Arctic lowlands in north-east Siberia were subjected to extensive landscape and environmental changes during the Late Quaternary. Coastal cliffs along the Arctic shelf seas expose terrestrial archives containing numerous palaeoenvironmental indicators (e.g., pollen, plant macro-fossils and mammal fossils) preserved in the permafrost. The presented sedimentological (grain size, magnetic susceptibility and biogeochemical parameters), cryolithological, geochronological (radiocarbon, accelerator mass spectrometry and infrared-stimulated luminescence), heavy mineral and palaeoecological records from Cape Mamontov Klyk record the environmental dynamics of an Arctic shelf lowland east of the Taymyr Peninsula, and thus, near the eastern edge of the Eurasian ice sheet, over the last 60 Ky. This region is also considered to be the westernmost part of Beringia, the non-glaciated landmass that lay between the Eurasian and the Laurentian ice caps during the Late Pleistocene. Several units and subunits of sand deposits, peat–sand alternations, ice-rich palaeocryosol sequences (Ice Complex) and peaty fillings of thermokarst depressions and valleys were presented. The recorded proxy data sets reflect cold stadial climate conditions between 60 and 50 Kya, moderate inderstadial conditions between 50 and 25 Kya and cold stadial conditions from 25 to 15 Kya. The Late Pleistocene to Holocene transition, including the Allerød warm period, the early to middle Holocene thermal optimum and the late Holocene cooling, are also recorded. Three phases of landscape dynamic (fluvial/alluvial, irregular slope run-off and thermokarst) were presented in a schematic model, and were subsequently correlated with the supraregional environmental history between the Early Weichselian and the Holocene.

PERMAFROST AND PERIGLACIAL FEATURES | Yedoma: Late Pleistocene Ice-Rich Syngenetic Permafrost of Beringia

Syngenetically frozen deposits that are fine-grained and ice-rich are widely distributed in the lowlands of northeastern Siberia, Alaska, and northwestern Canada. These late Pleistocene sediments are specific to this region summarized as Beringia, and have been termed ‘Ice Complex’ or ‘Yedoma’ in Siberia, and ‘muck’ in North America. Silt is their dominant material, but they also include abundant organic matter preserved in permafrost since the time of deposition. Vegetation and faunal reconstructions indicate that the sediments aggraded largely under a cryoxeric environment characterized by graminoid- and forb-rich vegetation that supported a grazing megafauna population during the Pleistocene.

Application of Landsat-7 satellite data and a DEM for the quantification of thermokarst-affected terrain types in the periglacial Lena–Anabar coastal lowland

Extensive parts of Arctic permafrost-dominated lowlands were affected by large-scale permafrost degradation, mainly through Holocene thermokarst activity. The effect of thermokarst is nowadays observed in most periglacial lowlands of the Arctic. Since permafrost degradation is a consequence as well as a signifi cant factor of global climate change, it is necessary to develop effi cient methods for the quantifi cation of its past and current magnitude. We developed a procedure for the quantifi cation of periglacial lowland terrain types with a focus on degradation features and applied it to the Cape Mamontov Klyk area in the western Laptev Sea region. Our terrain classifi cation approach was based on a combination of geospatial datasets, including a supervised maximum likelihood classifi cation applied to Landsat-7 ETM+ data and digital elevation data. Thirteen fi nal terrain surface classes were extracted and subsequently characterized in terms of relevance to thermokarst and degradation of ice-rich deposits. 78% of the investigated area was estimated to be affected by permafrost degradation. The overall classifi cation accuracy was 79%. Thermokarst did not develop evenly on the coastal plain, as indicated by the increasingly dense coverage of thermokarst-related areas from south to north. This regionally focused procedure can be extended to other areas to provide the highly detailed periglacial terrain mapping capabilities currently lacking in global-scale permafrost datasets.

Spectral characterization of periglacial surfaces and geomorphological units in the Arctic Lena Delta using field spectrometry and remote sensing

Abstract Important environmental parameters in arctic periglacial landscapes (i.e. permafrost temperature, active-layer depth, soil moisture, precipitation, vegetation cover) will very likely change in a warming climate. The thawing of permafrost, especially, might cause massive landscape changes due to thermokarst and an enhanced release of greenhouse gasses from the large amounts of carbon stored in frozen deposits, resulting in positive climate-warming feedback. For the identification, mapping, and quantification of such changes on various scales up to the entire circum-Arctic, remote sensing and spatial data analysis are essential tools. In this study an extensive field-work dataset including spectral surface properties, vegetation, soils, and geomorphology was acquired in the largest Arctic delta formed by a single river, the Siberian Lena River Delta. A portable field spectrometer (ASD FieldSpec Pro FR®) was used for spectral surveys of terrain surfaces, and optical satellite data (Landsat Enhanced Thematic Mapper (ETM+), CHRIS-Proba) were used for the characterization, manual mapping, and automatic classification of typical periglacial land-cover units in the Lena Delta. Qualitative data from soils, vegetation, soil moisture, and relief units were correlated with the field-spectral data and catalogued for a wide variety of surface types. The wide range of micro- and meso-scale variations of periglacial surface features in the delta results in distinctive spectral characteristics for different land-cover units. The three main delta terraces could also be spectrally separated and characterized. The present dataset provides a basis for further spectral data acquisitions in the Lena Delta and for comparisons with periglacial surfaces from other regions.