Research of domanic source rock by pyrolytic gas chromatography-mass spectrometry method

We applied new novel approach based on pyrolytic gas chromatography-mass spectrometry technology (Py-GCMS) developed by Frontier Lab company (Japan) in order to get the same data as it can be acquired by using conventional core analyzer. Experimental part describes the detailed measurement procedure, temperature program and outcomes acquired by using IFP 160000 as a standard sample. We have managed to demonstrate accuracy and reproducibility of tests for the domanic source rock samples and its kerogen extracted respectively. In results of this analytical challenge we were able to get pyrograms providing the S1 (free hydrocarbons), S2 (potential hydrocarbons), Tmax (temperature at which the maximum rate of hydrocarbon generation is reached) information with level of confidence we usually could see doing conventional core analyzer tests. Some important conclusions regarding petroleum generation and thermal maturity have been made. S1 and S2 significantly decrease for kerogen samples with Tmax growth at the same time. Moreover mass spectra data of core samples pyrolizates can be collected easily to detect certain groups of compounds. Sulfur-containing compounds temperature extracted by Py-GCMS can be measured for example. Py-GCMS technology fully comply with mainstream analytical protocol for whole-rock or kerogen analysis and even more, Py-GCMS has a lot of advantages against conventional approach providing us additional valuable information about a sample

The effective action and quantum gauge transformations

The local symmetry transformations of the quantum effective action for general gauge theory are found. Additional symmetries arise under consideration of background gauges. Together with "trivial" gauge transformations, vanishing on mass shell, they can be used for construction simple gauge generators. For example, for the Yang-Mills theory the classically invariant effective action is obtained, reproducing DeWitt's result. For rank one theories a natural generalization is proposed.Comment: Revtex, 11 pages; added reference

Geochemical variations in the Upper Kazanian (Middle Permian) stratotype section, Russia

© 2020 IOP Publishing Ltd. All rights reserved. The present paper shows elemental and carbon and strontium isotope composition of the Upper Kazanian (Middle Permian) stratotype section Pechishchi, Russia. A new version of Noinsky's cycles scheme has been obtained for Martinet and Sougy's Diagram types of carbonates, with the geochemical indices values changing within marine, evaporate and clastic beds. The δ13Ccarb values vary within interval 0 - +10‰ V-PDB with a mean value 6.2 ‰ V-PDB. The negative excursions of δ13Ccarb values (with amplitudes 2-8 ‰) are assigned as significant land-derived sedimentary inputs. The values of 87Sr/86Sr ratio in the data set of 17 samples change from 0.707267 to 0.707417 (mean value 0. 70734). On standard 87Sr/86Sr curve these values correspond to the interval 273 - 268 Ma

Some Aspects Concerning the Formation of Clayey Sediments of the Urzhumian Stage by the Geochemical Data on the Reference Section

This paper considers the genesis of clayey sediments of the Urzhumian stage (the Middle Permian) by the XRF data on samples from the reference section. It was revealed that clayey sediments were formed as a result of the low temperature transformation of smeсtite into other phillosilicates, which occurred during the Urzhumian stage due to the arid climate, specific composition of provenance rocks, sharp and rapid changes in the hydrochemical composition of the sedimentation basin (variation in Mg2+), and terrigenous flows containing feldspars in the amount sufficient for enrichment of the sediments with Al3+ and К+ through the bioinert processes at the stage of diagenesis

Ge-Si ratio for assessing the chemical weathering intensity at the paleocene-eocene boundary in ancient transuralian Basin

© 2020 Tomsk Polytechnic University, Publishing House. All rights reserved. Relevance. Diatomites and their transitional differences formed in the Paleocene-Eocene marine basin are one of the most widespread in the near-surface occurrence of sedimentary rocks in the vast territory of the Trans-Urals. At the same time, with regard to the genetic aspects of such rocks, the discussion on the fundamental sources of silica for formation remains still relevant. An urgent task is to analyze the role of each of two factors in the origin of rocks - continental weathering and upwelling activities. The ratio of Ge to Si can potentially be considered as a tool for deciphering the source of silica in biogenic siliceous rocks, since germanium is delivered to the rock by incorporation into biogenic opal; Ge introduction into the rock from other sources during the diagenesis is not significant, which makes the results indicatively valuable. The main aim is estimation of the chemical weathering intensity at the boundary of the Paleocene and Eocene in the Trans-Urals based on the study of the ratio of Ge and Si in diatomites of different ages. The methods: field studies, X-ray fluorescence analysis, inductively coupled plasma mass spectrometry, scanning electron microscopy. The results. The paper contains the first results of estimation of chemical weathering intensity at the boundary of the Paleocene and Eocene in the Trans-Urals by analyzing the ratios of germanium and silicon in bulk diatomite samples and bioclastic preparations, where clay material was removed. The Ge/Si ratios in bioclastic preparations from the Paleocene (Brusyana section) and Eocene (Irbit deposit) differ almost twofold. The obtained values should be considered as mark that the intensity of chemical weathering undergoes serious changes at this boundary: intensive chemical weathering, strengthening of the hydrological cycle during the PETM period determined an increase in the supply of dissolved silica to the marine basin during the accumulation of biosiliceous rocks in the territory of modern Trans-Urals. The weakening of tectonic movements and land peneplenisation within the East Ural contributed to the weathering intensification. This provided an additional transfer of siliceous matter in the form of true and colloidal solutions to the sedimentation basin for the biosiliceous rocks accumulation. The amount of silica influx from land over a relatively short period of time became more noticeable in the overall balance of silica supplied to the sedimentation basin. For the same reason, i. e. the presence of an additional source of silicic acid, the gross SiO2 content in the Paleocene diatomites is slightly higher than in the Eocene

Paleosols from the Kazanian red beds of the Sentyak section, Russia

This article summarizes the results of a comprehensive study of paleosol profiles in the Lower Kama Region – from the Kazanian reference section near Sentyak and from the reference section of the boundary deposits of the Ufimian and Kazanian in Elabuga. The paleosol profiles in the Kazanian deposits were identified, and their features were analyzed to reconstruct the paleoclimatic and paleolandscape conditions. The following three types of paleosols were singled out, differing from one another in their degree of development and pedogenic features: Protosols and moderately and strongly developed Calcisols. The latter proved to be characteristic only of the Lower Kazanian deposits. Based on the obtained sedimentological and paleontological characteristics of the host rocks, the fluviolacustrine depositional settings were reconstructed. The pedofeatures of the paleosols (slickensides, carbonate nodules) indicate a seasonally warm climate. The mean annual precipitation inferred from the geochemical indices of the paleosol profiles is 539 and 476 mm/yr for the Lower and Upper Kazanian paleosols, respectively, which, along with the pedofeatures, is indicative of a subhumid/semiarid climate. The oxygen isotopic composition of the carbonate nodules from the paleosols reflects some aridization of the climate in the Early Kazanian (29.7‰ SMOW δ18O) compared to the Ufimian (18.7‰ SMOW δ18O) and Late Kazanian (22.3‰ SMOW δ18O) times. The lack of gley features argues for the automorphic character of the paleosols, while their small thickness, truncated upper horizons, and weak development in the Upper Kazanian deposits suggest that the rate of sedimentation exceeded the rate of soil formation

Loess-like siltstones from the urzhumian (middle permian) red beds of Kazan Volga Region, Russia

© 2020 International Multidisciplinary Scientific Geoconference. All rights reserved. Here we focused on the massive, non-pedogenic, loess-like siltstones, which are common within the fluvio-lacustrine Middle Permian red sediments of Kazan Volga region, to refine their depositional settings. Sedimentological, mineralogical and geochemical methods including field description, grain size analysis, optical microscopy, bulk geochemistry and X-ray diffraction, were used. Siltstone facies from the Urzhumian red beds of this region are represented by two types: laminated and massive, the last one is commonly modified by pedogenesis. Pedogenically non-altered massive siltstones often look like loessites and are considered by some researches as an aeolian sediments. These siltstones commonly occur in tabular beds of 1-1.2 m thick and underlain by paleosols and overlain by laminated siltstones or lacustrine carbonates. The matrix-supported internal structure, the poor grain sorting, a significant proportion of sand material, gley spots along with convolute microstructures, microlamination fragments and brecciation signs suggest the fluvial character of sedimentation of these siltstones. Lack of fossils and root traces, sheet-like tabular beds with non-erosional contacts and their structural features indicate the rapid sedimentation, most likely, by sheetfloods. Gradual transitions from the massive loess-like to pedogenically modified siltstones and then to developed paleosols can be traced in the Urzhumian succession on the different stratigraphic levels. The mineral composition of studied rocks and geochemical indices including chemical index of alteration (CIA) are similar to those of the underlying rocks, which may indicate the same provenance of siliciclastic material and/or its redeposition. Thus, the massive loess-like siltstones under study are interpreted as fluvial, floodplain or mudflat deposits, formed by rapid sedimentation of sandy-silty material

COMPARING THE RESULTS OF LINEAMENT ANALYSIS WITH ISOTOPE GEOCHEMISTRY DATA

This article presents the results of a geochemical survey carried out in the southwestern part of the Siberian platform, within the Sayan-Yenisei (Angara) syneclise (a superorder Riphean-Middle Paleozoic structure). The object of research was hydrocarbon gases contained in the subsoil rocks (clays). The subsoil samples were taken from the bottom of boreholes (40 mm in diameter) made with an electric drill. The sampling depth was 0.6–1 m. Further laboratory studies included chromatographic and isotope analysis. Lineament analysis of the digital elevation model was carried out as a complementary study. One of the lineament analysis results was a lineament density map, which reflects the permeability (macro-fracture density) of the sedimentary cover. This allowed a comparison of the macro-fracture density with the gas content and isotopic composition. The study revealed that gases with a high content of heavy isotopes tend to gather in the low permeability areas. This can be explained by the fact that the gases disperse quickly within fractured zones, and deep gases should be expected only in the areas with strong cap rocks, i.e. in the areas with low macro-fracture density where stable hydrocarbon deposits have already formed

Erratum to: Crustal Source of Pb and S at the Yubileynoe Porphyry Gold Deposit (Southern Urals, Kazakhstan): High Precision Pb–Pb and δ³⁴S Data (Geology of Ore Deposits, (2021), 63, 3, (173-184), 10.1134/S107570152103003X)

An Erratum to this paper has been published: https://doi.org/10.1134/S1075701521300012

Crustal Source of Pb and S at the Yubileynoe Porphyry Gold Deposit (Southern Urals, Kazakhstan): High Precision Pb–Pb and δ³⁴S Data

Abstract: The Yubileinoe large gold deposit, located at the southern end of the Magnitogorsk megazone, is the only known representative of the Au–porphyry systems in the Southern Urals. It is genetically related to granitoids formed in a suprasubduction setting under mature oceanic island arc environment/setting. The obtained isotope (Pb–Pb and δ34S) data indicate the input of mineral-forming components into the Au–porphyry system of the deposit, mainly from granitoid melts, confirming a common source of ore material and ore-bearing granitoids. The geochemical and isotopic characteristics of granitoids indicate the leading role in their genesis of the crustal source, which is considered Late Precambrian continental crust