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The comparison of the AMS units in Jelínek (a, c, e) and Flinn-type (b, d, f) diagrams.

The comparison of the AMS units in Jelínek (a, c, e) and Flinn-type (b, d, f) diagrams.

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Magnetic fabric (MF) investigations complemented by geochemical and grain surface analyses of the understudied and controversial marine isotope stage (MIS) 5 b, 4 and 3 loess deposits in the Lower Volga region, Russia show that the material has been transported and deposited by wind and to a large extent experienced post-depositional reworking. Gra...

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... the depth dependent separation of the 9 AMS units, their MF characteristics were compared in Jelínek and Flinn-type diagrams (Fig. 5). The grouping of the samples from the different AMS units illustrate that the R unit contains mostly oblate samples but also several prolate ones, with uniform low anisotropy. F varies more than L for most samples, some plot along the line indicating neutral shape control ( Fig. 5a and b). Two subgroups exist among the P group: P3 is, ...
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... characteristics were compared in Jelínek and Flinn-type diagrams (Fig. 5). The grouping of the samples from the different AMS units illustrate that the R unit contains mostly oblate samples but also several prolate ones, with uniform low anisotropy. F varies more than L for most samples, some plot along the line indicating neutral shape control ( Fig. 5a and b). Two subgroups exist among the P group: P3 is, apart from two exceptions, strongly oblate with anisotropies >2% for 6 samples, whereas P1 and P2 are mostly prolate and show low anisotropies ( Fig. 5c and d). Also, for the IR groups two sets of samples can be distinguished. An increase of Pj and F with increasingly oblate T, together ...
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... prolate ones, with uniform low anisotropy. F varies more than L for most samples, some plot along the line indicating neutral shape control ( Fig. 5a and b). Two subgroups exist among the P group: P3 is, apart from two exceptions, strongly oblate with anisotropies >2% for 6 samples, whereas P1 and P2 are mostly prolate and show low anisotropies ( Fig. 5c and d). Also, for the IR groups two sets of samples can be distinguished. An increase of Pj and F with increasingly oblate T, together with constant L, are seen for one set of IR samples despite strong scatter of the data. These observations are most obvious for IR5 (Fig. 5e and f). A smaller subgroup of IR samples displays prolate character, ...
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... samples, whereas P1 and P2 are mostly prolate and show low anisotropies ( Fig. 5c and d). Also, for the IR groups two sets of samples can be distinguished. An increase of Pj and F with increasingly oblate T, together with constant L, are seen for one set of IR samples despite strong scatter of the data. These observations are most obvious for IR5 (Fig. 5e and f). A smaller subgroup of IR samples displays prolate character, which does not coincide with an increase in Pj (Fig. 5e). It appears that the mostly prolate IR subgroup is similar to P1 and P2 as well as to a few samples from ...
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... samples can be distinguished. An increase of Pj and F with increasingly oblate T, together with constant L, are seen for one set of IR samples despite strong scatter of the data. These observations are most obvious for IR5 (Fig. 5e and f). A smaller subgroup of IR samples displays prolate character, which does not coincide with an increase in Pj (Fig. 5e). It appears that the mostly prolate IR subgroup is similar to P1 and P2 as well as to a few samples from ...
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... the alignment of the principal susceptibility axes (Fig. 6b) and the predominantly foliated, oblate character of R ( Fig. 5a and b) indicate a primary aeolian MF (Table 2). However, post-depositional influence and the development of secondary MF is suggested by the prolate character of several samples within this unit and the varying inclination of the principal susceptibility axes (Supp. Table 3; Figs. 4 and 6b). Despite some scattering, a flowaligned MF is ...
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... and Pj. Similar to that seen in P1, L is comparably high in relation to F. Considering the vertical component of k max , its prolate character, together with the indication for weathering from the element ratios, the high CIA and the alteration of grain surfaces (SEM), P2 appears to be affected by pedogenesis, most profoundly in its upper part ( Fig. 5c and d, 6d and 7, Table 2). The less distinct sign of chemical weathering in the lower section of P2 might be in relation to frost action and the connected potential removal of clay minerals. This is suggested by the presence of distinct cracks/wedges in this part of the pedogenic ...
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... contains several samples of foliation controlled primary, aeolian MF (Fig. 6e). The lack of a preferred orientation and the predominately oblate character, might indicate gravitational affected MF but could also reflect the dominance of paramagnetic matrix minerals (Fig. 5c). P3 also differs from P1 and P2 by showing significantly higher F and Pj, even compared to the pristine loess layer R (Figs. 3 and 5). Similar to Lagroix and Banerjee (2004b), who also observed increasing F and Pj for palaeosols, our results contrast with the observation from some loess studies that Pj is systematically lower in ...
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... the straight grooves on the grain surfaces are known from glacial environments and rather connected to the grains' provenance than in situ frost action (Mahaney, 2002). The secondary MF of IR2 shows evidence for reworking (Fig. 6g). Samples with strong F, T > 0, and high Pj stand in contrast to samples with prolate character, weak F, and low Pj (Fig. 5e and f). The latter group of characteristic properties are similar to those of P1 and P2, and several R samples (Figs. 3 and 5). The partly strong F and pronounced L suggest the occurrence of frost action. Frost action may also be reflected by the biaxial prolate MF (Fig. 6g; Lagroix and Banerjee, 2004a). Considering the presence of cracks in ...

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... Thus the region provides reference stratotypes used in the compilation of the stratigraphic and Pleistocene palaeogeographic scheme for European Russia and a correlation scheme for events in Northern Eurasia. The relevance of the Lower Volga region to palaeogeographic studies is expressed in the large number of representative Quaternary sections, their completeness, the content of sediments of different genesis (both marine and subaerial), the richness of the palaeontological material, and the ready availability for study (Moskvitin, 1962;Goretskiy, 1966;Fedorov, 1978;Rychagov, 1997;Svitoch and Yanina, 1997;Lavrushin et al., 2014;Yanina, 2014;Van de Velde et al., 2020;Költringer et al., 2021;Költringer et al., 2022 and many others). ...
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... Quaternary sediments of considerable thickness cover the Northern Caspian lowland and crop out along the lower branch of the Volga River. These deposits represent important environmental archives and allow the study of climate variations in the region and their relationship with Northern Hemisphere glaciations, Volga River dynamics and Caspian Sea level oscillations (e.g., Grichuk, 1954;Rychagov, 1997;Lebedeva et al., 2018;Költringer et al., 2020Költringer et al., , 2021Taratunina et al., 2021;Makeev et al., 2021). Over the past century, considerable research has described and discussed the marine and fluvial sequences of the Middle to Late Quaternary sediment sections in the Lower Volga valley (Fedorov, 1957;Svitoch, 2014), with the aim of addressing the timing and extent of changes in Caspian Sea level (Zastrozhnov et al., 2020;Leroy et al., 2014;Tudryn et al., 2013). ...
... More recently the intercalated subaerial terrestrial deposits have also received attention and have been described as loess-palaeosol sequences Makeev et al., 2021;Költringer et al., 2020Költringer et al., , 2021. These aeolian deposits, made up of near-source reworked Volga alluvium, are widely distributed in the Northern Caspian lowland (Kurbanov et al., 2018a(Kurbanov et al., , 2018bKöltringer et al., 2022) and show signs of both pedogenic and cryogenic reworking (Yanina, 2012;Költringer et al., 2020Költringer et al., , 2021Lebedeva et al., 2018;Makeev et al., 2021;Rogov et al., 2020;Taratunina et al., 2021). ...
... More recently the intercalated subaerial terrestrial deposits have also received attention and have been described as loess-palaeosol sequences Makeev et al., 2021;Költringer et al., 2020Költringer et al., , 2021. These aeolian deposits, made up of near-source reworked Volga alluvium, are widely distributed in the Northern Caspian lowland (Kurbanov et al., 2018a(Kurbanov et al., , 2018bKöltringer et al., 2022) and show signs of both pedogenic and cryogenic reworking (Yanina, 2012;Költringer et al., 2020Költringer et al., , 2021Lebedeva et al., 2018;Makeev et al., 2021;Rogov et al., 2020;Taratunina et al., 2021). As such, Lower Volga loess is also of great value for palaeoclimate reconstruction, in addition to the marine deposits in the Northern Caspian lowland (Kurbanov et al., 2018a(Kurbanov et al., , 2018bKöltringer et al., 2020Költringer et al., , 2021. ...
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... Despite the long history of studying the LPSs of the Ciscaucasia, there is still no exhaustive explanation of the origin of such a high thickness. Also, questions about the sources of loess material and the main directions of aeolian transport for individual stages of the Quaternary period have not been fully resolved (Fedorovich, 1960;Balaev, Tsarev, 1964;Rozycki, 1991;Sazhin et al., 2012;2013;Költringer, 2021;2022). Mainly, these questions were associated with the lack of a reasonable and generally accepted chronostratigraphic scheme for the LPSs of Ciscaucasia. ...
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... The thick loessic deposits in the Thames Valley may be explained by the proximity of the region to North Sea basin dust sources. Another possible explanation may involve the influence of the Thames itself, in a situation comparable to other great loess rivers such as the Danube, Yellow, Mississippi and Volga rivers (Újvári et al., 2012;Nie et al., 2015;Muhs et al., 2018;Költringer et al., 2021;Fenn et al., 2022). However, in contrast to these rivers, there is no obvious mechanism for the production of large amounts of silt in the Thames basin. ...
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... The main stages of the Caspian Sea evolution -the major transgressionsprovide the stratigraphical basis for the Quaternary of Central Asia, Eastern Caucasus and the southern part of East European plain. The Lower Volga River valley is ideally suited for investigating the Pleistocene history of the Caspian Sea, and a series of sections has been characterized here over a long period of research (Fedorov, 1957;Vasiliev, 1961;Moskvitin, 1962;Svitoch and Yanina, 1997;Költringer et al., 2021;Kurbanov et al., 2021). These sections contain a unique record of the Quaternary history of the Caspian Sea, in the form of alternating marine and subaerial deposits. ...
... In recent years, systematic studies have contributed to the first work on the structure of the loess-soil series in the Lower Volga region Lebedeva et al., 2018;Rogov et al., 2020;Taratunina et al., 2021;Makeev et al., 2021), and on their palaeogeographic significance (Bolikhovskaya et al., 2017;Yanina et al., 2021). Some initial climate reconstructions have also been carried out in the region (Bolikhovskaya et al., 2017;Költringer et al., 2020Költringer et al., , 2021. However, these studies lacked reliable and detailed independent ages since they are based on only a few age-tie points so that a detailed reconstruction of loess-palaeosol formation through time was not possible. ...
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... This MF type is the most common in loess deposits and has widely been used for estimating paleowind directions (e.g. Banerjee, 2002, Zhu et al., 2004;Zhang et al., 2014;Gao et al., 2021;Költringer et al., 2021). ...
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