Suchergebnisse

Bauxite rocks of the pre-Jurassic complex of the Urmano- Archinskaya area of the West Siberian Plate are considered, which were formed mainly due to proluvial-deluvial-alluvial redeposition of weathering products into karst traps. The parent rocks could be volcanic rock of intermediate composition and clay deposits, drilled by wells into erosion-tectonic uplift of the basement to the north-east of the study area. The reservoir properties and alumina enrichment of study sediments are due to the leaching by hydrothermal solutions of bauxite rocks during deep-burial diagenesis.

The carbon and oxygen isotopic composition of secondary carbonates from acidic effusives fro investigated. Ϭ13С (VPDB) and Ϭ18О (VSMOW) values of siderite vary from –6,6 to –2,4‰ m the top of the Western Siberia pre-Jurassic complex (Tomsk Region) was and from 7,8 to 12,3‰, while Ϭ13С and Ϭ18О values of calcite vary from –8,9 to –8,4‰ and from 2,5 to 3,7‰ respectively. Light oxygen isotopic composition indicates formation of studied carbonates from heated hydrothermal solutions.

The study of secondary changes of acidic effusives with reservoir properties from the top of the Western Siberia pre-Jurassic complex (Tomsk Region) was produced. Lithological, petrographic and mineralogical features of these rocks indicate their change by low-temperature hydrothermal solutions, while weathering products, which are widely spread at the top of the basement, have not been clearly defined. Reservoir properties of studied rocks were formed probably due to fracturing and leaching.

Based on study of the lithology of the Taman Konkian, reflecting the accumulation of mainly clays, the two types carbonate rocks related to planktonogenic and microbial sediments were determined. Planktonogenic and microbial carbonate rocks have different carbon and oxygen isotopic compositions. Based on statistical processes, including Lomb-Scargle and REDFIT periodograms, cyclicities related to solar forcing were detected.

The shallow-marine sediments of the Middle Miocene (mainly the Konkian) of the Eastern Georgia (Eastern Paratethys, Kura basin) were investigated by cyclostratigraphy methods. Time series analysis (Lomb-Scargle and REDFIT periodograms, Gaussian filters) revealed statistically significant signal with 2,4–2,7 m wavelength corresponding most likely to the precession cycle. Based on statistical processes, a sedimentation rate of the studied sediments from 8,75 to 13,75 cm/kyr for different depositional setting was detected. We suggest that the studied Eastern Georgia Konkian sediments (Sartaganian and Veselyankian beds) accumulated during of at least 475–600 kyr. The Sartaganian (beds with most diverse marine fauna of the Konkian) can be correlated with interval of highest sea-level rise of TB 2,5 cycle.

With the goal to correlate the magnetostratigraphic data of the Eastern Paratethys obtained by researchers in different years a rockmagnetic and paleomagnetic investigations of the Tarkhanian sediments of the Skelya section was carried out. The main carrier of the natural remanent magnetization is titanomagnetite in the Argunian beds of the Tarkhanian regional stage; in addition to titanomagnetite there is iron sulfide (monoclinic pyrrhotite and/or greigite) in the deposits of the Terskian and Kuvinian beds. The paleomagnetic fold test of natural remanent magnetization directions, recorded in the rocks of the Argunian beds, is positive, which indicates a pre-folding age of the magnetization formation. A comparison with the magnetochronological scale GTS 2020 shows that the normal polarity interval in the lower part of the Argunian beds can presumably be compared with the С5Bn chron. The reversal polarity interval in the upper part of the Argunian beds is with C5ADr. The age of the С5Bn/C5ADr boundary can be estimated as ~14.7 Ma.

Geochemical studies of sarmatian clays and silts of the Kerch Strait and the Taman Peninsula to determine the paleogeographic features of their formation were researched for the first time. Proxies for paleosalinity and paleobatimetry were built using geochemical data to specify previous reconstructions. Two regressive (early Sarmatian; from the middle of the Late Sarmatian) and two transgressive (middle and early Late Sarmatian; late Late Sarmatian — early Meotian) stages in the development of the study area were distinguished. Data on salinity in ppm were obtained. The effectiveness of the used methods of interpreting geochemical data in paleogeographic reconstructions, which can subsequently be successfully applied to deposits deprived of fossil remains or characterized by a weak indicator function of the species of fauna and flora, is proved.