The polygenetic hypothesis of Yedoma origin – comparing grain-size distributions of Alaskan and Siberian Yedoma
The formation of late Pleistocene Yedoma in western Beringia (Siberia) is still widely debated. Moreover, different geological and cryostratigraphical views on Yedoma exist between researchers focusing on western or eastern Beringia (Alaska and Northwest Canada). These differences largely concern th...
| Main Authors: | , , , , |
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| Format: | Conference Object |
| Language: | unknown |
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Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research International Permafrost Association
2016
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| Online Access: | https://epic.awi.de/id/eprint/42019/ https://epic.awi.de/id/eprint/42019/1/Yedoma_polygenetics.pdf https://hdl.handle.net/10013/epic.48806 https://hdl.handle.net/10013/epic.48806.d001 |
| Summary: | The formation of late Pleistocene Yedoma in western Beringia (Siberia) is still widely debated. Moreover, different geological and cryostratigraphical views on Yedoma exist between researchers focusing on western or eastern Beringia (Alaska and Northwest Canada). These differences largely concern the prominence of the role of eolian processes. In particular, previous studies on Yedoma in the Yukon Territories and Alaska interpret these deposits as being largely loess or re-transported loess (muck). In contrast, several hypotheses have emerged over decades of research in the extensive Siberian Yedoma region, including (1) alluvial genesis, (2) ice-sheet-dammed basin sediments, (3) deltaic formation, (4) proluvial and slope deposits, (5) cryogenic-aeolian deposits, (6) nival deposits, and (7) polygenetic origins. Characteristics that most studies agree on include the dominance of large syngenetic ice wedges, mainly allochthonous silty to sandy sediment deposition in low-center polygons in combination with deposition of mainly autochthonous organic remnants from plants and animals, very harsh continental, glacial climate conditions. In terms of landscape and relief characteristics, various Yedoma types seem to exist across the extensive region where Yedoma does occur, ranging from spatially confined Yedoma valley fills including slopes to vast accumulation plains on Arctic lowlands and shelves. Accordingly, we here support the notion that Yedoma may have different depositional properties and genetic origins under a common frame of similar environmental and climatic conditions during the Late Pleistocene. This hypothesis is known as polygenetic formation of Yedoma. An important aspect of Yedoma is the dominating presence of excess ground ice. Ice wedges and segregated intra-sedimentary ice constitute the majority of this deposit by volume (50-80%) in most Yedoma regions and are thus one of the most critical factors in deposit genesis in contrast to accumulations of silty to sandy deposits in temperate regions. The ... |
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