The lithofacies zonality and lithmological structure of Eifelian deposits of Dobrudja Foredeep

: pp. 50 - 62
Received: February 03, 2016
Institute of Geology and Geochemistry of Combustible Minerals of the National Academy of Science of Ukraine
Institute of Geology and Geochemistry of Combustible Minerals of National Ukrainian Academy of Sciences
Institute of Geology and Geochemistry of Combustible Minerals of National Ukrainian Academy of Sciences
Institute of Geology and Geochemistry of Combustible Minerals of the National Academy of Science of Ukraine
Institute of Geology and Geochemistry of Combustible Minerals of NAS of Ukraine

Purpose. The main purpose of this work is studying of lithology features of sedimentary complex of Eifelian age within Biloliskyi block of Dobrudja Foredeep. Methods. Methods include lithofacial, lithmological and mineralogy-petrographical analyses. Results. Lithology structure of sections of Eifelian deposits has been determined. It is presented with variable interlayering of sulphate (anhydrites), carbonate (limestones, dolomites, and marlstones) and terrigenous (sandstones, siltstones, argillites) rocks. Six types of deposit section have been distinguished: dolomite-limestone-anhydrite, dolomite (limestone)-marlstone-anhydrite, argillite-marlstone-anhydrite, anhydrite-limestone-dolomite, dolomite-anhydrite-limestone, dolomite-anhydrite-marlstone; which characterized by some lateral zonality of occurrence, that constructed lithologic models display. Thus, anhydrites dominate in the sections of south-western part, dolomites and limestones in the sections of northern and southern, marlstones and argillites in the sections of central part of Biloliskyi block. Regional distribution of basal carbonate-terrigenous-clayey measures, which represents intergrade layers from terrigenous deposits of Lower Devonian to sulphate-carbonate deposits of Middle and Upper Devonian, has been determined. Petrographic features of main types of rocks have been studied in detail. The lithmological sections have been done. They show that Eifelian strata is characterized by storied structure that developed in four regional and subregional sulphate bedsets, demarcated by terrigenous-carbonate horizons. Scientific novelty. For the first time lithologic sections of Eifelian deposits and their typification have been done. The lithofacies and lithmological models have been constructed, which allow turning out spatial-age variation of lithologic structure of sedimentary deposits of Eifelian age. Practical significance. Studying of features of lithologic structure of strata, making lithofacies and lithmological models will contribute to clarification of some stratigraphical questions, finding out spatial-temporal occurrence of sedimentary complexes of different composition and genesis sediments. All this serves for geologic (lithogenetic) basis for more reasonable prognosis of spatial- temporal occurrence oil and gas objects connected, first of all, with limestone-dolomite accumulated bodies.

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