Last glacial loess dynamics in the Southern Caucasus (NE-Armenia) and the phenomenon of missing loess deposition during MIS-2.

Autor: Wolf D; Institute of Geography, Technische Universität Dresden, Helmholtzstr. 10, 01069, Dresden, Germany. daniel_wolf@tu-dresden.de., Lomax J; Department of Geography, Justus Liebig University Giessen, Senckenbergstr. 1, 35390, Giessen, Germany., Sahakyan L; Institute of Geological Sciences, National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019, Yerevan, Armenia., Hovakimyan H; Institute of Geological Sciences, National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019, Yerevan, Armenia., Profe J; Department of Geography, Justus Liebig University Giessen, Senckenbergstr. 1, 35390, Giessen, Germany., Schulte P; Department of Geography, RWTH Aachen University, Wüllnerstr. 5b, 52062, Aachen, Germany., von Suchodoletz H; Institute of Geography, Leipzig University, Johannisallee 19a, 04103, Leipzig, Germany., Richter C; Institute of Geography, Technische Universität Dresden, Helmholtzstr. 10, 01069, Dresden, Germany., Hambach U; BayCEER & Chair of Geomorphology, University of Bayreuth, 95440, Bayreuth, Germany., Fuchs M; Department of Geography, Justus Liebig University Giessen, Senckenbergstr. 1, 35390, Giessen, Germany., Faust D; Institute of Geography, Technische Universität Dresden, Helmholtzstr. 10, 01069, Dresden, Germany.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2022 Aug 02; Vol. 12 (1), pp. 13269. Date of Electronic Publication: 2022 Aug 02.
DOI: 10.1038/s41598-022-17021-5
Abstrakt: The Marine Isotope Stage (MIS) 2 is considered the coldest, driest and stormiest period during the last Glacial-Interglacial cycle in large parts of Eurasia. This resulted from strongly decreased northern hemisphere temperature and related maximum extension of northern ice sheets that strongly reinforced large-scale circulation modes such as westerlies and East Asian Winter Monsoon driven by the Siberian High. Normally, this intensified circulation is reflected by maximum loess deposition in numerous loess regions spanning Europe and Asia. However, here we present a new loess record from the Caucasus region in NE-Armenia providing evidence in support of heavily reduced or even lacking loess formation during the MIS-2. Owing to implementations of comprehensible luminescence dating work and a provenance survey using rock magnetic and geochemical data, we are able to define distinct loess formation phases and to retrace sediment transport pathways. By comparing our results to other Eurasian palaeo-records, we unveil general atmospheric circulation modes that are most likely responsible for loess formation in the Southern Caucasus. Moreover, we try to test different scenarios to explain lacking loess formation during MIS-2. In line with other archive information, we suggest that loess formation was hampered by higher regional moisture conditions caused by a southward-shift of westerlies and renewed moisture absorption over the Black Sea. Our results show that modifications of MIS-2 circulation modes induced a very heterogeneous moisture distribution, particularly in the lower mid-latitudes of Eurasia producing a juxtaposition of very dry (morphodynamically active) and moderately dry (morphodynamically stable) areas.
(© 2022. The Author(s).)
Databáze: MEDLINE
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