From the Allerød to the mid-Holocene: Palynological evidence from the south basin of the Caspian Sea

This article has been made available through the Brunel Open Access Publishing Fund. Copyright @ The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.Pollen and dinoflagellate cysts have been analysed in a core from the south basin of the Caspian Sea, providing a picture of respectively past vegetation and water salinity for the Late Pleistocene to middle Holocene. A relatively sharp lithological change at 0.86 m depth reflects a shift from detrital silts to carbonates-rich fine silts. From this depth upwards, a Holocene chronology is built based on ten radiocarbon dates on ostracod shells and bulk carbonates. From the vegetation point of view, the Late Pleistocene deserts and steppes were partially replaced in the most sheltered areas by an open woodland with Pinus, Juniperus-Hippophae-Elaeagnus and even Alnus-Quercus-Pterocarya and Fraxinus, related to the Allerød palynozone. This was interrupted by the Younger Dryas palynozone when Artemisia reaches a maximum in a first instance followed by a very dry phase with only a slight return of Pinus and Quercus and the rare presence of Ulmus-Zelkova. From 11.5 to 8.4 cal. ka BP, an open landscape dominated by shrubs such as Ephedra and progressively increasing Quercus appeared. The final spread of diverse evergreen and deciduous trees is delayed and occurs after 8.4 cal. ka BP. It is suggested that this delay is caused by an arid climate in the Early Holocene linked to high insolation and perhaps to a lake effect. The dinocyst assemblages fluctuate between slightly brackish (Pyxidinopsis psilata and Spiniferites cruciformis, 7 psu and lower) and more brackish (Impagidinium caspienense, ∼13 psu). In the Lateglacial (Khvalynian highstand), the assemblages remained dominated by relative low salinity taxa. A late and brief increase of salinity occurred prior to 11.2 cal. ka BP associated with the Mangyshlak lowstand. It is suggested that it was caused by a brief drop in meltwater flow from both the north and the southeast (Uzboy) and a likely evaporation increase. This lowstand occurs quasi at the same time as the end of a longer lowstand in the Black Sea. The freshest waters are then inferred as having occurred between 8.4 and ≤4.4 cal. ka BP, linked to a connection with the Amu Darya and the melting glaciers on the Pamir Mountains. The Caspian Sea is a sensitive environment, easily perturbed by global climatic changes, such as the Allerød and Holocene warming, and the Lateglacial and Younger Dryas cooling, as well as by regional changes in its hydrography, such as shifts in the Eurasian meltwater and the Volga and Amu Darya inflows.Centre National de la Recherche Scientifique, Franc

Gyromagnetic remanence acquired by greigite (Fe3S4) during static three-axis alternating field demagnetization

A magnetic study was carried out on lacustrine sediments from the Zoigebasin, Tibetan Plateau, in order to obtain a better understanding ofpalaeoclimatic changes there. Gyromagnetic remanence (GRM) acquisitionis unexpectedly observed during static three-axis alternating field (AF)demagnetization in about 20 per cent of a large number of samples. X-raydiffraction (XRD) analysis on a magnetic extract clearly shows thatgreigite is the dominant magnetic mineral carrier. Scanning electronmicroscopy (SEM) reveals that the greigite particles are in the grainsize range of 200-300 nm, possibly in the single-domain state. Greigiteclumps of about 3 mu m size are sealed by silicates. Fitting of XRDpeaks yields a crystalline coherence length of about 15 nm, indicatingthat the particles seen in the SEM are polycrystalline.GRM intensities of most samples are of the same order as the NRM, whileothers show much stronger GRM although their magnetic properties aresimilar. Variation of the demagnetization sequence confirms that GRM ismainly produced perpendicular to the AF direction. The anisotropydirection can be derived from GRM, but more systematic studies areneeded for detailed conclusions. An attempt to correct for GRM faileddue to high GRM intensities and because smaller GRM acquisition was alsofound along the demagnetization axis. Behaviours of acquisition and AFdemagnetization of GRM are comparable with those of NRM, ARM, IRM,indicating fine grain sizes of remanence carriers

The Ponto-Caspian basin as a final trap for southeastern Scandinavian Ice-Sheet meltwater

This paper provides new data on the evolution of the Caspian Sea and Black Sea from the Last Glacial Maximum until ca. 12 cal kyr BP. We present new analyses (clay mineralogy, grain-size, Nd isotopes and pollen) applied to sediments from the river terraces in the lower Volga, from the middle Caspian Sea and from the western part of the Black Sea. The results show that during the last deglaciation, the Ponto-Caspian basin collected meltwater and fine-grained sediment from the southern margin of the Scandinavian Ice Sheet (SIS) via the Dniepr and Volga Rivers. It induced the deposition of characteristic red-brownish/chocolate-coloured illite-rich sediments (Red Layers in the Black Sea and Chocolate Clays in the Caspian Sea) that originated from the Baltic Shield area according to Nd data. This general evolution, common to both seas was nevertheless differentiated over time due to the specificities of their catchment areas and due to the movement of the southern margin of the SIS. Our results indicate that in the eastern part of the East European Plain, the meltwater from the SIS margin supplied the Caspian Sea during the deglaciation until ∼13.8 cal kyr BP, and possibly from the LGM. That led to the Early Khvalynian transgressive stage(s) and Chocolate Clays deposition in the now-emerged northern flat part of the Caspian Sea (river terraces in the modern lower Volga) and in its middle basin. In the western part of the East European Plain, our results confirm the release of meltwater from the SIS margin into the Black Sea that occurred between 17.2 and 15.7 cal kyr BP, as previously proposed. Indeed, recent findings concerning the evolution of the southern margin of the SIS and the Black Sea, show that during the last deglaciation, occurred a westward release of meltwater into the North Atlantic (between ca. 20 and 16.7 cal kyr BP), and a southward one into the Black Sea (between 17.2 and 15.7 cal kyr BP). After the Red Layers/Chocolate Clays deposition in both seas and until 12 cal kyr BP, smectite became the dominant clay mineral. The East European Plain is clearly identified as the source for smectite in the Caspian Sea sediments. In the Black Sea, smectite originated either from the East European Plain or from the Danube River catchment. Previous studies consider smectite as being only of Anatolian origin. However, our results highlight both, the European source for smectite and the impact of this source on the depositional environment of the Black Sea during considered period

The Role of Polish Women in Shaping and Supporting the Identity of Children of Polish Origin in Polish Saturday Schools in France

Historia migracji Polek i Polaków do Francji jest długa, bogata i zróżnicowana pod względem płci migrujących osób, wykształcenia, struktury wieku oraz powodów emigracji. Ostatnia fala emigracji, która opuściła kraj w okresie przystąpienia Polski do Unii Europejskiej i otwarcia francuskiego rynku pracy dla Polaków, charakteryzuje się wyraźną samoorganizacją w sferze praktyk edukacyjnych dla dzieci. Oddolna mobilizacja edukacyjna jest zdecydowanie zdeterminowana przez płeć, a jej siłę i determinację unaoczniają liczne szkoły społeczne powstałe z indywidualnych i kolektywnych inicjatyw. W artykule przedstawię wstępne wyniki moich badań pochodzące z wywiadów pogłębionych z liderkami i nauczycielkami tamtejszego środowiska polonijnego oraz uzupełnię je wnioskami z obserwacji uczestniczącej.The history of migration of Polish women and men to France is long, rich and diverse in terms of gender, education level, age structure and purpose of emigration. The last wave of emigration, which dates to around Poland’s accession to the European Union and the opening of the French labor market for Poles, is characterized by a clear self-organization in the sphere of educational practices for children. The grassroots of educational mobilization is definitely determined by gender and numerous supplementary schools created from individual and collective initiatives illustrate its strength and determination. In the article I present the preliminary results of my research resulting from in-depth interviews with leaders and teachers of the Polish diaspora in France. I conclude with the analysis of questionnaires and participant observation

Magnetic mineral variations of South Caspian Sea sediments at laminae scale.

International audienc

Comparison of quantity and quality of the yield of selected species and varieties of grasses at different harvest dates

В 1972-1983 гг. проводился опыт с последовательностью уборки перевого и второго укоса злаковых трав. Исследовали влияние фенологической и календарной даты уборки первого укоса и период отрастания второго укоса на урожай сухого вещества, а также содержание белка и волокна у видов и сортов злаковых трав. При последовательной уборке первого укоса у раннеспелых злаков установлена связь между качеством урожая и фенологической фазой. По мере старения растений повышалось содержание волокна, а снижалось содержание белка. Качество позднеспелых видов ухудшалось более рано, чем это ухудшение следовало бы из их ростовой фазы. Таким образом при возделывании видов с различной раннеспелостью невозможно получить (позже 25 мая) соответствующего качества корм. Возделывание же сортов с дифференцированной раннеспелостью позволяло получать растительную массу желаемого качества. Качество корма с второго отроста зависело как от периода отрастания так и от сортовых признаков в рамках данного вида.An experiment with succesive harvest of the first and second cut of grasses was carried out in the period 1972-1983. The effect if phenologic and calendar date of the first cut harvest and the regrowth period of the second cut on the dry matter yield, protein and fibre content in species and varieties of grasses, were investigated. At the succesive harvest of the first cut a relationship between the quality and phenologic phase of earlier ripening species and varieties of grasses has been proved. Along with senescence of plants increased the fibre and decreased the protein content. The quality of later ripening species worsened earlier than it would result from the growth phase. Thus in cultivation of species with different earliness no appropriate quality fodder could be ensured (after May 25). On the other hand, the cultivation of varieties of differentiated earliness enabled to gain plant matter of a wanted quality. The quality of the second regrowth fodder depended both on the regrowth period and varietal traits within the given grass species

Magnetic minerals as indicators of major environmental change in holocene black sea sediments: preliminary results

International audienc