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- Költringer, Chiara, et al.
(author)
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Quaternary sediment sources and loess transport pathways in the Black Sea - Caspian Sea region identified by detrital zircon U-Pb geochronology
- 2022
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In: Global and Planetary Change. - : Elsevier. - 0921-8181 .- 1872-6364. ; 209
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Journal article (peer-reviewed)abstract
- Constraining the controls on the distribution of sediment at a continental scale is a critical step in understandinglong-term landscape and climate evolution. In particular, understanding of the role of rivers in wider sedimentrouting and impacts on aeolian loess formation on a continental scale remains limited. Extensive Quaternaryloess deposits are present on the East European Plain and in the Black Sea - Caspian Sea region and are associatedwith major rivers draining numerous surrounding cratonic and orogenic hinterland areas. Coupled with this,complex changes in local and global sea level have affected the extent and drainage of the Caspian Sea and theBlack Sea, and Quaternary glaciations have impinged on the northern margin of the East European Plain. Thissuggests that sediment routing and loess formation may show complex patterns and controls. Here, we applyU–Pb dating of detrital zircons from fluvial, marine and aeolian (dominantly loess) sedimentary records on theEast European Plain and in the Black Sea - Caspian Sea region. This shows a strong control of large rivers on thedistribution of sediments at a continental scale in the region, through long-distance transport of several 1000 km,sourced from continental and mountain glacier areas prior to marine or atmospheric reworking and trans-portation. Strong spatial variability in zircon U–Pb data from loess deposits on the East European Plain revealsmultiple diverse sources to the different individual loess sections, whereas no significant temporal variability inloess source is detected during the Late Pleistocene of the Lower Volga loess in South Russia. While the sedimentsupply from glacial areas via rivers plays an important role for the provenance of East European Plain loessdeposits, our data indicate that the stark spatial diversity in loess provenance on the East European Plain is oftendriven by the input of multiple local sources. Similar to the loess, marine sediments from different basins of theBlack Sea and the Caspian Sea also show significant spatial variability. This variability is controlled by the ba-thymetry of the seas, leading to sedimentary intermixing by sea currents within, but not between differentseparated sea basins. A direct comparison of marine and aeolian sediments at the same depositional site suggeststhat although loess and marine sediments are both dominantly sourced from river sediments containing fartravelled sedimentary material, local sources play a more important role in many loess deposits.
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- Lukyanycheva, Mariya S., et al.
(author)
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Dating post-LGM aeolian sedimentation and the Late Palaeolithic in Central Yakutia (northeastern Siberia)
- 2024
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In: Quaternary Geochronology. - : Elsevier. - 1871-1014 .- 1878-0350. ; 83, s. 101563-101563
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Journal article (peer-reviewed)abstract
- Central Yakutia is a large region in northeastern Siberia characterized by extensive permafrost, large river valleys, mountain glaciers, and large massifs of aeolian sands; the geological history of the region is complex and, at present, poorly constrained. In recent years, it has been shown that aeolian sands cover up to 60% of large parts of Central Yakutia. This paper presents the results of luminescence dating of aeolian sedimentation at the Diring Yuriakh Palaeolithic site located in the middle reaches of the Lena River. Field studies identified several thick units of aeolian sand, which cover an old deflation surface with Late (Duktai culture) and Early Palaeolithic (Diring culture) artefacts. The reliability of the OSL chronology was assessed by comparison of ages based on the optically stimulated luminescence from quartz and the infra-red stimulated luminescence from potassium-rich feldspars; these age pairs are in good agreement, implying that at least the quartz grains were sufficiently bleached before sedimentation. We obtained OSL ages that reflect three periods of accumulation between the LGM and the Holocene: ∼21 ka, 15-14 ka, and 12.5–10 ka. These periods of accumulation broadly coincide with global cooling episodes during the Last Glacial Maximum, the Older Dryas, and the Younger Dryas, with some extension into subsequent warmer intervals, whereas the intervening intervals without preserved sediments are taken to reflect dune stability during warmer periods. The sand on the terraces, sourced from alluvial bars in the river channel, was blown up the valley slope during cold and dry periods when the vegetation cover was sparse. When the climate warmed, the vegetation took some time to spread, and so the accumulation of aeolian sand on the high terraces continued into the warm periods. We also infer periods of deflation (wind erosion) that occurred before 21 ka and between 20 and 15 ka, presumably due to increased aeolian activity and localized remobilization of sediment. The new OSL chronology shows that the younger artefacts located at the cape of Diring Yuriakh, belonging to the Late Palaeolithic Duktai culture, are older than 15 ka. The new ages also show that the post-LGM aeolian sand sequences at Diring Yuriakh are correlated with the regionally developed subaerial Dolkuma Formation.
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