Beenchime Salaatinsky crater in northern Yakutia - origin and late quaternary records in the 8-km circular structure


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Lutz.Schirrmeister [ at ] awi.de

Abstract

Beenchime Salaatinsky Crater (BSC) is a 8 km wide, multi-million-year-old ring structure located west of the Olenyok River in northern Yakutia. This is an area that has not been covered by Pleistocene time glaciers (Ehlers, J., Gibbard, P.L., 2007; Niessen et al., 2013). Short-term scientific goals of our study were (i) to reveal the origin of the crater (impact crater or volcanic crater) based on mineral analysis and (ii) to evaluate prospective Quaternary sediment records in the basin. Following earlier geomorphological surveys, it is assumed that the basin is the result of a volcanic explosion similar to Kimberlite Pipes elsewhere found in Yakutia (Pinchuk et al., 1971). Alternatively, a meteorite impact has been blamed, because suevitic breccias were identified (Mikhailov et al., 1979, Masaitis, 1999). According to geomorphological age estimates, the crater is believed to be between 65 and 40±20 Ma old (EarthImpactDatabase), but a robust physical dating is actually missing. We sampled several landforms of the basin interior after digging soil pits into the ground and extracting short cores from the underlying permafrost. Sample sites were a peat plateau and ancient river terraces. In addition, a modern lake depression in the central part, 300 m in diameter and 4 m deep at maximum, has been studied using 50 MHz ground penetrating radar profiles and short cores. Bedrock samples were taken from representative sites of outcropping Paleozoic formations inside and outside BSC. Thin sections from bedrock were analyzed using polarized light microscopy. In fact, shocked quartz grains with PDFs (planar deformation features) were found in samples taken from a Permian sandstone outcropping in the crater interior. The crystallographic orientations were measured using a U-stage microscope. Some other samples of the crater rim were found to be only slightly shocked. We sum up our results in a preliminary scenario, which suggests a Paleozoic meteoritic impact event, a Mesozoic overburdening of the area and a subsequent erosion in the course of the Olenyok Uplift. Finally, we propose late Quaternary landscape dynamics based on sediment dating using AMS 14C and sediment properties in the crater; fluvial sediment transport is documented for the MIS 3 and MIS 1 periods whereas mid to late Holocene lake formation results from thermokarst dynamics. A distinct grain size change in the fine silt fraction from coarser to finer indicates increasing aridity in the area with lake level lowering during late Holocene time. References EarthImpactDatabase, 2019. http://www.passc.net/EarthImpactDatabase/Beyenchimesalaatin.html. Ehlers, J., Gibbard, P.L., 2007. The extent and chronology of Cenozoic global glaciation. Quaternary International, 164, 6-20. Niessen, F. et al., 2013. Repeated Pleistocene glaciation of the East Siberian continental margin. Nature Geoscience, 6 (10), 842. Grieve, R.A., 1987. Terrestrial impact structures. Annual Review of Earth and Planetary Sciences, 15, 245-270. Masaitis, V.L., 1999. Impact structures of northeastern Eurasia: The territories of Russia and adjacent countries. Meteoritics & Planetary Science, 34, 5, 691-711. Mikhaylov, M.V. et al., 1979. The Beyenchime-Salaata meteorite crater. Doklady Akademii Nauk SSSR, 245, 76-78 [in Russian]. Pinchuk L.Y., 1971. Morphology and genesis of Beenchime-Salaatin depression - Kimberlite volcanism and prospects of primary diamond content of the north-eastern Siberian platform. Proceedings Arctic Geology Research Institute, Leningrad, 123-126 [in Russian].



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Conference (Poster)
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Not peer-reviewed
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Published
Event Details
Processes and Palaeo-environmental changes in the Arctic: from past to present (PalaeoArc), 20 May 2019 - 24 May 2019, Poznań.
Eprint ID
53072
Cite as
Schwamborn, G. , Manthey, C. , Raschke, U. , Schirrmeister, L. , Zhuravlev, A. , Oparin, N. and Prokopiev, A. V. (2019): Beenchime Salaatinsky crater in northern Yakutia - origin and late quaternary records in the 8-km circular structure , Processes and Palaeo-environmental changes in the Arctic: from past to present (PalaeoArc), Poznań, 20 May 2019 - 24 May 2019 .


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