Holocene deposits in the Mangyshlak Peninsula, North Caspian sea regionстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 11 мая 2021 г.
Аннотация:Comprehensive analysis of the data of highprecision seismoacoustic profiling, drilling and sampling of deposits using seabed corers, biostratigraphic studies, and radiocarbon age data was performed for the first time for Mangyshlak sediments in several bottom sites of the North Caspian. It was found that the Mangyshlak sediments comprise numerous linearly stretched depressions of 5–10 m in depth (morphologically similar to modern substeppe ilmen areas in the Volga River delta), which are covered by the Novocaspian sedimentary cover, and river incisions (among them the largest Volga River valley). In addition, the Mangy
shlak sediments comprise the deltaic alluvial fans of different sizes along the shelf zone of the North Caspian. Analysis of mollusks and biogenic remains indicates that accumulation of the Mangyshlak sediments occurred in freshwater and slightly salty water environments under various hydrodynamic and hydrochemical conditions. According to radiocarbon dating of organic matter, the Mangyshlak sediments formed during sea regression in the range of 10–8 ka (isotopic age) or 11.5–8.5 ka (calendar age). Several types of sediments are
distinguished: clayeycarbonate sediments, enriched with organic matter up to the formation of sapropel and peat, accumulated at the lowest sea level; weakly calcareous siltyclayey silts, formed during the subsequent intense filling of paleodepressions with terrigenous material. The features of the mineral composition of sediments are as follows: polymineral composition of clayey material with a high proportion of hydromica and disordered mixedlayered formations, a high content of minerals of the epidote group, amphiboles, and other
accessory minerals. All of this indicates a genetic relationship between the Mangyshlak sediments and the Volga terrigenous material.