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On the basis of location levels of push marginal formations and maximal distribution heights of charted lateral moraine, the
surface form of the Late Valdai ice sheet in the region of Khibini and Lovozerskii massifs during cool stadial phases of the
Middle and Younger Dryas was reconstructed. It has been established that the glacier surface came to 700 m and 500 m, respectively,
and its inclination varied from 30 to 70 m per 10 km, which is well below that in marginal fields of ice sheets of Western
Greenland and East Antarctica. The maximal ice thickness in the Middle Dryas came to about 600 m, and in the Younger Dryas,
it was about 400 m. The inclination of the glacier surface increased during the cool stadial phase. On the whole, it coincides
well with the drift directions of detrital sediments by ice streams, established by the transfer direction of detrital sediments,
orientation of drumlins, ice scars, and other factors of ice activity. 相似文献
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V. Ya. Yevzerov 《Lithology and Mineral Resources》2007,42(6):505-514
Rock associations in fluvioglacial deltas reflect climatic cyclicity. Climatic cycles determined the accumulation of sediments in the association of hydrodynamic, debris, and turbidity flows. Hydrodynamic flows formed successively the near-summit part of the delta (pebble and boulder) and its frontal slope in the course of accumulation of the pebble, sand-pebble or sandy and, less common pebble-boulder layers inclined toward the basin. Decrease in energy of flows in the basin resulted in successive reduction of particle grain-size along these layers and toward distal areas of the delta during its formation. The formation of the deltaic frontal slope was followed by the initiation of debris and turbidity flows. They spread along the floor of marine and freshwater basins and deposited successively gravel material, different-size sands, and varved clay. In the study region, sediments of the association under consideration include sand and sand-gravel deposits (up to 40% of total reserves in the Murmansk region) and almost all known brick clay deposits. 相似文献
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Geoffrey D. Corner Vasili V. Kolka Vladimir Y. Yevzerov Jakob J. Mller 《Global and Planetary Change》2001,31(1-4)
A relative sea-level curve for the Holocene is constructed for Polyarny on the Kola Peninsula, northwest Russia. The curve is based on 18 radiocarbon dates of isolation contacts, identified from lithological and diatomological criteria, in nine lake basins situated between 12 and 57 m a.s.l. Most of the lakes show a conformable, regressive I–II–III (marine–transitional–freshwater) facies succession, indicating a postglacial history comprising an early (10,000–9000 radiocarbon years BP) phase of rapid, glacio-isostatically induced emergence (5 cm year−1) and a later phase (after 7000 years BP,) having a moderate rate of emergence (<0.5 cm year−1). Three lakes together record a phase of very low rate of emergence or slight sea-level rise at a level of 27 m a.s.l., between 8500 and 7000 years BP, which correlates with the regional Tapes transgression. Pollen stratigraphy in the highest lake shows that the area was deglaciated before the Younger Dryas and that previously reconstructed Younger Dryas glacier margins along the north Kola coast lie too far north. 相似文献
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Analysis of materials on the geological structure and tectonics of the White Sea depression area suggests that this depression existed in the Middle Pleistocene and was connected with the World Ocean. It is still impossible to determine the exact time of its formation due to an insufficient knowledge of the depression loose cover. However it is most likely that the depression was formed in the Late Miocene and Early Pliocene, when after the regressive development of the continental margin the shelf subsidence began. Probably in the Holocene the divergent regime was replaced by the transform regime. This period saw the subsidence of the Kandalaksha graben to about 150 m and the formation of the Kolvitsa graben. The crystalline rocks surrounding Kandalaksha bay were involved in the subsidence which is reflected in the isobase curve of the glacioisostatic uplift of the area. The combined impact of the tectonic component and the glacioisostatic uplift led to a rise of tensions which discharge caused a high seismic activity of the Kandalaksha graben and its environs. 相似文献
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V. G. Bakhmutov V. Ya. Yevzerov V. V. Kolka 《Izvestiya Physics of the Solid Earth》2009,45(7):567-582
The genesis, varve, and paleomagnetic informativeness of glaciolacustrine sediments are considered based on paleomagnetic and lithological studies. The magnetic properties of varved clays from periglacial basins have been considered using the sedimentological model of formation of varved clays as products of glacial turbidity currents, which explains the differences in the magnetic characteristics and degree of paleomagnetic informativeness of these clays. The distal zone sediments (formed due to precipitation from glacial turbidity currents, suspension, and sometimes along the periphery of the proximal zone) are most successfully used to study secular variations. The possible errors of the secular variation records in varved clays and such errors in estimating annual bedding of these clays have been analyzed. It has been indicated that information about the composition, concentration, and magnetic fraction size should be completed with detailed lithological studies, which make it possible to reconstruct the character of clastic material income into a basin and to decipher a paleomagnetic record. An analysis of the magnetic susceptibility anisotropy parameters and the magnetization formation in a sediment makes it possible to take into account disturbances caused by the sedimentation process and, thereby, to detect a pure geomagnetic signal 相似文献
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