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A. B. Kuznetsov M. A. Semikhatov A. V. Maslov I. M. Gorokhov E. M. Prasolov M. T. Krupenin I. V. Kislova 《Stratigraphy and Geological Correlation》2006,14(6):602-628
New data on Sr-and C-isotopic systematics of carbonate rocks from the Upper Riphean stratotype (Karatau Group of the southern Urals) are obtained for several southwestern sections of the Bashkirian meganticlinorium, which have not been studied before. The results obtained supplement the Sr-and C-isotopic information for the group upper horizons thus detailing chemostratigraphic characterization of the entire succession. Limestone and dolostone samples used to analyze the Sr isotope composition satisfy strict geochemical criteria of the isotopic system retentivity and have been subjected to preliminary treatment in ammonium acetate to remove secondary carbonate phases. Data on 255 samples of carbonate rocks (171 studied for the first time) show that δ13C value varies in the Karatau Group succession from ?2.8 to +5.9 ‰ V-PDB with several in-phase excursions from the general trend in all the sections studied in the area 90 × 130 km. The δ13C variation trend demarcates several levels in the carbonate succession of the Karatau Group suitable for objectives of regional stratigraphy and for C-isotope chemostratigraphic subdivision of the Upper Riphean. The results of Sr isotopic analysis of 121 samples (51 unstudied before) from the Karatau Group imply that rocks in its lower part (the Katav Formation and basal horizon of the Inzer Formation) experienced considerable secondary alterations, while limestones and dolostones of the overlying interval of the group are frequently unaltered. In the “best” samples satisfying geochemical criteria of the isotopic system retentivity, the 87Sr/86Sr initial ratio increases from 0.70521–0.70532 in the lower Inzer deposits to 0.70611 in the upper Min’yar carbonates, decreasing to <0.70600 near the top of the latter. Above the regional hiatus separating the Min’yar and Uk formation, this ratio grows from 0.70533 to 0.70605–0.70609 in the limestone succession of the last formation. 相似文献
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E. M. Prasolov I. V. Tokarev G. D. Ginsburg V. A. Soloviev G. M. Eltsova 《Geo-Marine Letters》1999,19(1-2):84-88
He, Ar, Ne contents and 3He/4He, 4He/20Ne, and 40Ar/36Ar ratios in gas-hydrate bearing sea-floor sediments of the Håkon Mosby Mud Volcano show that Ne, Ar, and part of He are atmospheric. Nonatmospheric, deep He (3He/4He=0.9???10-8) is present in all samples. Helium isotopic composition suggests that its origin is uniform, crustal (radiogenic) and, probably, connected with mud volcano gases. Apparently deep helium is residual gas that remains in isolated volumes after hydrate formation. Measured helium content in hydrate gases is very low: 0.5–10?ppm. but in one particular sample it is very high: 7080?ppm. 相似文献
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V. G. Sakhno V. I. Gvozdev A. A. Alenicheva E. M. Prasolov N. V. Zarubina 《Doklady Earth Sciences》2012,443(1):308-315
U-Pb (SHRIMP) isotope dating of magmatic complexes of tungsten ore-magmatic systems (OMSs) resulted in a conclusion about
the close age (103–105 Ma) of their formation in the magmatic rock masses from the Tatibinsk plutonic series whose location
is controlled by the Sikhote-Alin’ strike-slip fault system. The OMSs are formed within the zones of strike-slip fault extensions
(“windows”) dipping into the mantle, which establishes the conditions for the participation of deep fluids in the generation
of melts at the level of crustal-mantle interaction. The new data from the study of the isotope composition of helium in the
fluid inclusions showed that the content of mantle helium in ores of tungsten OMSs is approximately 10%. 相似文献
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B.G Polyak E.M Prasolov V Čermák A.B Verkhovskiy 《Geochimica et cosmochimica acta》1985,49(3):695-699
The contents and isotopic composition of all noble gases in the fluids from two localities (Karlovy Vary and Franti?kovy Lázně) in Western Czechoslovakia are given. The data show: (1) atmospheric Ne, Ar, Kr and Xe, which indicates meteoric recharge; (2) excess He, attributed to radiogenic contributions; (3) a small excess of Ne, but the data shed no light on its origin. Even though there is no evidence of any juvenile component in these mineral waters, part of the dissolved He is believed to be of deep (mantle) origin.Correlation between the ratio He and heat flow has been reported in the literature: our data enabled a direct test of this relationship and proved its fairly good validity. The combined interpretation of the heat flow and isotopic composition shows that the local heat flow anomaly in the Kru?né Hory graben is of deep origin and was produced by the mass outflow which occurred during the Alpine activation of the Bohemian Massif. 相似文献
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B. G. Polyak A. L. Cheshko O. E. Kikvadze I. L. Kamensky E. M. Prasolov 《Lithology and Mineral Resources》2018,53(5):380-393
The paper presents data on the composition of a gas phase of underground fluids in the East Carpathian region, including 3He/4He, 40Ar/36Ar, and 4He/20Ne ratios. The argon isotope composition of these gases was used to estimate the fractions of atmospheric Aratm and radiogenic 40Arrad formed in the rocks, N2/Aratm ratio, and to reveal the admixture of nonatmogenic (“excess”) nitrogen in most samples. The CO2 content in gases positively correlates with the fraction of mantle component in fluid helium. At the same time, the CO2 content shows a negative correlation with the total helium (and light 3He enriching mantle derivatives), thus excluding the simultaneous influx of CO2 and helium from a common mantle source in the fluids. A wide spectrum of 3He/4He = R in gases of the region spanning three orders of magnitude confirms the concept of mixing of the crustal and mantle components in the helium. However, even gases with similar R values show a wide scatter of He concentrations. This is mainly caused by the additional influx of other gases: CH4 formed during OM transformation or CO2 released during the thermal metamorphism of carbonate sequences. Correlation of the CH4/3He ratio and the helium isotope composition in the Carpathian gases indicates the crustal origin of hydrocarbons, which formed economic gas pools in the Ciscarpathian Trough and the adjacent part of the Folded Carpathians. Lateral chemical and isotope variations revealed in the underground fluids are related to the tectonic zoning of the region. The helium isotope variations are also consistent with the geodynamic setting of the region (thinning of the crust and lithosphere towards the Pannonian Basin, growth of the background conductive heat flow and corresponding ascent of isotherms). In combination with geothermal data, they reflect specifics of the mantle heat-and-mass flow discharge. 相似文献
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