DBPapers
DOI: 10.5593/sgem2017/11/S01.043

MINERALOGICAL AND GEOCHEMICAL CHARACTERISTICS OF TERRIGENOUS SEDIMENTS VANAVAR FORMATION (SIBERIAN CRATON)

E.V. Korbovyak, P.A. Tishin, I.V. Afonin, O.V. Bether, V.A. Konovalova
Saturday 9 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7105-98-8 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 11, 337-344 pp, DOI: 10.5593/sgem2017/11/S01.043

ABSTRACT

The Vanavar Formation is a terrigenous horizon (1 to 200 m thick) at the boundary of the Tonian-Cryogenian and Ediacaran-Fortunian carbonate complexes. The geological position of the Vanavar Formation and the intensive facies variability do not permit a clear characterization of the conditions for its accumulation. Additional interest in the study of Vanavar Formation caused by its oil-and-gas bearing deposits. The objects of research are the core samples selected from well № 3 of Pridutsky area. The mineral and chemical composition of sedimentary rocks was studied for the reconstruction of sedimentation conditions. It is established that in the section of the Vanavar Formation three main packs are distinguished: the lower pack is composed of alternating sandstone with an admixture of argillites; the middle pack is composed of interlacing of greenish-gray and red-colored sandstones with argillites; the third pack is composed of intercalation of argillites with siltstones and sandstones. Lithotypes in the composition of different packs differ from one another in the granulometric composition; the degree of sorting and transformation of the composition of detrital material and authigenic minerals, and the structural-mineralogical type of cement. By the nature of the distribution of clay minerals in the section of the Vanavar Formation, palygorskite, palygorskite-mixed-layer and mixed-layer zones are set up from the bottom. The distribution of authigenic minerals makes it possible to isolate the dolomite, hematite-sulfate and halite zones. The volume of mineral zones coincides with the volume of previously allocated packs. Variations in the chemical composition of the rocks show that the upsurge of the Vanavar Formation increases the indices of maturity of the sediment, its distance from the source of drift, salinity of the sedimentary basin, which indicates a transgressive nature of sedimentation.

Keywords: Siberian craton, Vanavar formation, mineralogy, geochemistry, chemostratigraphy.

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