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O. G. Epshtein 《Lithology and Mineral Resources》2018,53(5):404-416
Common basal moraines display diverse glaciodynamic structures inherited from the parental moraine-containing ice. Since these glacial diamictons are marked by instable structure and composition, they can resemble sediments of another origin and their identification is a difficult task. We cannot make substantiated genetic conclusions based on certain lithological properties typical of glacial diamictons. Only a set of specific features can provide sufficiently reliable determination of their glacial nature. Other methodical approaches applied in different regions, the Barents Sea included, for the identification of glacial diamictons based on the highly superficial analysis of some (usually secondary) features lead to a biased genetic interpretation of moraines. 相似文献
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O. G. Epshtein A. G. Dlugach A. V. Starovoytov B. F. Romanyuk 《Lithology and Mineral Resources》2011,46(2):115-134
The areal geological-geophysical study of Quaternary sediments was carried out in two areas of the eastern Barents Sea (Central
Deep and Murmansk Bank). This communication is mainly dedicated to the results of seismoacoustic investigations. It has been
established that the Quaternary sequence unconformably overlying the pre-Cenozoic strata in the studied areas is as follows
(from bottom to top): marine-glaciomarine Late Glacial-Holocene sediments, massive diamictons (the main part of the section),
and glaciotectonites formed after the underlying Mesozoic unconsolidated sediments. The Pleistocene diamictons, origin of
which is still debatable, are the main studied object. They constitute two seismostratigraphic complexes (SSC). According
to the accepted stratigraphic subdivision, they are represented by the Upper Weichselian SSC III (Maximum Last Glaciation)
and Lower Weichselian SSC V (Middle Weichselian SSC IV is eroded here). Complexes SSC V and SSC III composed of till overlie
the older sediments with the exaration unconformity. Complex SSC V is preserved locally, while SSC III is characterized by
the regional distribution. Complex SSC III is universally enveloped unconformably without erosional surface by an acoustically
uniform thin-bedded member of Late Glacial-Holocene glaciomarine and marine sediments (SSC II+I). Unlike SSC V, SSC III demonstrates
lateral heterogeneity in both studied areas consisting of two seismofacies, one of which forms very specific acoustically
transparent bodies (ATBs). Sediments of SSC III avoided subsequent erosion. Therefore, their glacial nature is distinctly
reflected in the complex distribution of thickness and peculiar morphology of corresponding bodies. 相似文献
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O. G. Epshtein A. G. Dlugach A. V. Starovoytov B. F. Romanyuk 《Lithology and Mineral Resources》2011,46(3):220-249
Llithology of massive diamictons was studied in two areas of the eastern Barents Sea using cores and geophysical data. These
sediments dominate in the Pleistocene section as two seismostratigraphic complexes (SSC): Upper Weichselian (SSC III) and
locally distributed Lower Weichselian (SSC V). Diamictons of these complexes represent tills produced by the geological activity
of the Pleistocene Novaya Zemlya and Scandinavian ice sheets. The Upper Weichselian glacial sequence is laterally heterogeneous.
It includes two seismic facies represented by ordinary (overconsolidated) tills (they also constitute SSC V) and a spacious
moraine of the specific type with the normally consolidated sediments (they avoided compaction by the ice load) and certain
lithological specifics. The last glacial sediments were formed in a specific subglacial setting similar to the sediments under
fast ice streams of Antarctica. However, the specific features allow us to define these sediments as a new (Barents Sea) facies
of tills related to zones of intense basal melting of glaciers. 相似文献
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Doklady Earth Sciences - Analysis of the data of seismoacoustic investigations and geotechnical drilling in the Eastern Barents Sea has shown the following. The cover of the Upper Weichselian... 相似文献
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Doklady Earth Sciences - Analysis of the data of seismoacoustic investigations and engineering-geological drilling in the eastern Barents Sea has shown the following. The Quaternary sedimentary... 相似文献
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O. G. Epshtein 《Lithology and Mineral Resources》2018,53(4):270-282
The facies complex of basal moraines with glaciodynamic structures (common basal moraines) dominates among deposits of the given genetic type. These moraines represent glacial diamictons of diverse structure and lithology. Some of their features are also typical of sediments of other genetic types. Therefore, a comprehensive study of glacial diamictons and their occurrence mode on the glacial bed (unconsolidated or consolidated) within large outcrops is methodically correct. Only such studies can unravel the wide range of specific features typical of common basal moraines. 相似文献
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O. G. Epshtein 《Lithology and Mineral Resources》2017,52(2):125-146
The existing concepts of moraine/till formation are discussed and the available factual data on this issue are analyzed. It is concluded that active glaciers from the transported mineral matter make up exclusively basal moraines on the river bed. The latter moraines, which are composed of material directly deposited from the glacier base on the substrate, represent glacial diamicts. It is believed that material in these deposits always acquire a semisolid-solid (“stiff”) state. We identified a new type of glacial deposits–“mitis” basal moraines, which include the recently defined low consolidated glacial diamicts. Consequently, basal moraines are divided into two facies associations: moraines with glaciodynamic structures (common “stiff” moraines) and “mitis” moraines (M-moraines). Deposits of these associations are formed in different thermal zones (areas) of the ice sheet bed. Moraines of the first facies association are formed in melt zones. Therefore, they are characterized by different lithologies and overconsolidation. The M-moraines formed on the thawed glacial bed are marked by massive structure and low (normal) consolidation. They are subdivided into the Barents Sea and Antarctic types. 相似文献
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