A tale of two signals: Global and local influences on the Late Pleistocene loess sequences in Bulgarian Lower Danube

Fenn, Kaja; Thomas, David S.G.; Durcan, Julie A.; Millar, Ian L.; Vereș, Daniel; Piermattei, Alma; Lane, Christine

doi:10.1016/j.quascirev.2021.107264

Cited by 18 publications

(9 citation statements)

References 168 publications

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“…E.g., LPS in the lower Danube Basin clearly lack evidence for higher humidity during MIS-2. Instead, they show maximum loess accumulation rates 25 , 66 . Regions north of the Greater Caucasus showed severe loess deposition during MIS-2, too 100 , 103 .…”

Section: Discussionmentioning

confidence: 96%

“…Regions north of the Greater Caucasus showed severe loess deposition during MIS-2, too 100 , 103 . In case of the lower Danube Basin, it is assumed that increased loess deposition during MIS-2 was caused by stronger effects of the SH that reached far west into E and SE Europe and blocked the Atlantic influences 25 , 66 . This, in turn, shows that the mountain range of the Greater Caucasus formed a kind of climate barrier that sheltered the Kura Basin and surrounding areas against the influences of the SH during MIS-2.…”

Section: Discussionmentioning

confidence: 99%

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

Wolf

Lomax

Sahakyan

et al. 2022

Sci Rep

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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.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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

Wolf

Lomax

Sahakyan

et al. 2022

Sci Rep

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“…2), which indicates different depositional rates. This further implies local influences on the development of each profile on a sub-orbital scale, as suggested by Fenn et al (2021).…”

Section: Research Area and Materialsmentioning

confidence: 87%

Implications of the geochemistry of L1LL1 (MIS2) loess in Poland for paleoenvironment and new normalizing values for loess-focused multi-elemental analyses

Skurzyński,

Jary,

Fenn

et al. 2024

Quat. res.

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Loess paleoenvironmental reconstructions on regional to supra-regional scales have recently gained much attention. Geochemistry comparisons in relation to reference datasets, such as the Upper Continental Crust (UCC) data, have furthered our understanding of the climatic and geomorphological conditions under which terrestrial sites have developed. However, UCC data differs from loess, thereby obscuring important features, and the existing “average loess” datasets also are not sufficient for modern investigations. In this study, we examine the youngest Polish loess (L1LL1 = MIS 2, ca. 26–15 ka) for its suitability as a new, loess-focused reference dataset. Eighty-nine samples from seven sites were analyzed, using inductively coupled plasma spectrometry. The loess had assumedly been homogenized during transportation and/or sedimentary recycling (LaN/SmN = 3.34–4.06, median 3.78; Eu/Eu* = 0.46–0.66, median 0.55; GdN/YbN = 1.08–1.49, median 1.26), and weakly affected by pre- or post-depositional weathering (CIA = 53.64–69.12, median 57.69). The statistically significant differences between sites in elemental medians were mostly conditioned by variations in grain size and in the “fresh” to “re-deposited” sediment ratio. Nonetheless, the overall geochemical composition homogeneity provided a basis for the estimation of Polish Median Loess (PML) data, as determined for 41 chemical elements. When used, PML data highlight differences between loess regions in Europe, thereby providing a tool for cross-continental comparisons.

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“…There is an increasing balance of evidence indicating spatial variability in loess stratigraphy relating to spatial differences in accumulation rates and palaeo-topography, particularly in piedmont regions (e.g., Fitzsimmons, 2017;Dave et al, 2023a), although in aggregate it may still be possible to make regional correlations and identify "representative" type sections (e.g., Marković et al, 2015a). Even over scales of tens to hundreds of meters, variability in stratigraphy may be observed (e.g., Fitzsimmons et al, 2013;Fenn et al, 2021). Furthermore, although the thick loess sequences exposed in the Tajik Depression have long been recognized for their potential as archives down to at least the Brunhes-Matuyama boundary (e.g., Dodonov et al, 2006;Yang et al, 2006, Jia et al, 2018Dodonov et al, 2006, Lü et al, 2020, few sections have been investigated in high resolution and with robust dating over the last full glacial cycle.…”

Section: Considerations Of Loess Stratigraphy In the Tajik Depressionmentioning

confidence: 99%

Variability in geochemical weathering indices in loess over the last full glacial cycle at Karamaidan, central Asia (Tajikistan)

Aquino,

Scardia,

Prud’homme

et al. 2024

Front. Earth Sci.

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This study presents the first quantitative assessment of weathering conditions in the Tajikistan depression throughout the last full glacial cycle. We employed geochemical and magnetic susceptibility analyses to investigate various weathering indices (WIs), with the CPA and FENG indices identified as the most suitable for this region. Our results confirm the formation of a robust pedocomplex, PS2, during the OIS5 interglacial phase, while primary loess deposition occurred during the interstadials. The presence of a weak paleosol, PS1, suggests that OIS3 was not significantly pronounced, and sediment transport and deposition continued during this period. Furthermore, we assessed the effectiveness of various climatic transfer functions, including some recently developed specifically for Chinese loess. These transfer functions have also shown promising applicability to the loess of Central Asia, producing realistic climate trends that are, however, still to be taken with caution. The MAT and mean annual precipitation generated with these functions show for the last interglacial period about 13°C and 665 mm, thus higher temperatures and lower precipitation than the current conditions of 10.8°C and 730 mm. These results indicate a significant increase (c. 15%) in both temperature and precipitation compared to the stadial periods.

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A tale of two signals: Global and local influences on the Late Pleistocene loess sequences in Bulgarian Lower Danube

Cited by 18 publications

References 168 publications

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

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

Implications of the geochemistry of L1LL1 (MIS2) loess in Poland for paleoenvironment and new normalizing values for loess-focused multi-elemental analyses

Variability in geochemical weathering indices in loess over the last full glacial cycle at Karamaidan, central Asia (Tajikistan)

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