Age and geodynamic setting of the formation of the dess gold-silver deposit (North Stanovoi metallogenic zone,southeastern fringes of the North Asian Craton)     

I. V. Buchko  A. A. Sorokin  V. A. Ponomarchuk  A. V. Travin  A. P. Sorokin  Ir. V. Buchko 《Doklady Earth Sciences》2010,435(2):1560-1563

This article discusses the results of ⁴⁰Ar/³⁹Ar geochronological studies on the age of the gold-silver mineralization of the Dess occurrence hosted by the granitoids of the Tynda-Bakaran rock complex, which is 129–128 Ma. This estimate coincides with the time of the formation of the Mo mineralization (125–122 Ma) hosted by the rocks of the same rock complex. This allows dating the Au-Ag and Mo mineralizations from the same ore formation period that manifests itself in the granitoids of the North Stanovoi metallogenic belt that were formed in the environment of a transform continental margin. There exists the following sequence of changes in the mineral occurrences from the south to the north: Au-Ag-Au-Mo(Au).  相似文献   

Scope of bacterial concentration of gold in technogenic placers of upper priamurye     

N. G. Kuimova  A. P. Sorokin 《Doklady Earth Sciences》2010,430(1):43-47

At present, there is a reliable proof that microorganisms in rocks and soils can accumulate and crystallize gold. Earlier the authors have shown the mechanisms of biogenic mineralization of gold; however, a question consistently arose about the scope of the possible concentration of noble metals by the biomass of microorganisms. This work presents an estimate of the scope of gold concentration by the bacterial biomass in placer deposits based on the calculation of the number and the biomass of heterotrophic aerobic bacteria in soil and above-ore horizons and the determination of their activity of interaction with gold. The investigations were performed in Upper Priamurye by the example of the Aprelsk technogenic placer and, for comparison, in the oxidation zone of the Snezhinka ore occurrence.  相似文献   

The age and geochemistry of volcanic rocks on the eastern flank of the Umlekan–Ogodzha volcanoplutonic belt (Amur region)     

A.A. Sorokin  A.P. Sorokin  V.A. Ponomarchuk  A.V. Travin 《Russian Geology and Geophysics》2010,51(4):369-379

⁴⁰Ar/³⁹Ar dating yielded the reliable ages of andesite from the Unerikan complex (102.1 ± 1.4 Ma) and basaltic andesite from the Burunda complex (107.3 ± 2.4 Ma). The established age of volcanism is close to one of the stages of formation of the Khingan–Okhotsk volcanoplutonic belt. The petrography and geochemistry of basic, normal-basic, and normal rocks point to their dual character: They combine features specific for tholeiitic and calc-alkalic rocks. Most likely, these rocks formed in the setting of transform continental margin.  相似文献   

The Triassic stage of mafic magmatism in the Dzhugdzhur–Stanovoi superterrane (southern framing of the North Asian craton)     

I.V. Buchko  A.A. Sorokin  E.B. Sal'nikova  A.B. Kotov  S.D. Velikoslavinskii  A.M. Larin  A.E. Izokh  S.Z. Yakovleva 《Russian Geology and Geophysics》2010,51(11):1157-1166

With U-Pb zircon dating, the ages of the Ul'degit (228 ± 1 Ma) and Chek-Chikan (203 ± 1 Ma) mafic massifs were determined. These massifs were earlier considered to form at the Early Precambrian stage of the geologic evolution of the Dzhugdzhur–Stanovoi superterrane. In geochemical features the igneous rocks of the massifs show relation with a within-plate source, on the one hand, and are similar to igneous rocks of subduction zones, on the other. They might have formed after subduction, which caused the intrusion of gabbroids of the Lucha massif (248 ± 1 Ma) and diorites of the Tok-Algoma complex (238 ± 2 Ma), followed by the fracturing of the subducted plate.  相似文献   

Adenine oxidation by pyrite-generated hydroxyl radicals     

Corey A Cohn  Shawn C Fisher  Bruce J Brownawell  Martin AA Schoonen 《Geochemical transactions》2010,11(1):2

Cellular exposure to particulate matter with concomitant formation of reactive oxygen species (ROS) and oxidization of biomolecules may lead to negative health outcomes. Evaluating the particle-induced formation of ROS and the oxidation products from reaction of ROS with biomolecules is useful for gaining a mechanistic understanding of particle-induced oxidative stress. Aqueous suspensions of pyrite particles have been shown to form hydroxyl radicals and degrade nucleic acids. Reactions between pyrite-induced hydroxyl radicals and nucleic acid bases, however, remain to be determined. Here, we compared the oxidation of adenine by Fenton-generated (i.e., ferrous iron and hydrogen peroxide) hydroxyl radicals to adenine oxidation by hydroxyl radicals generated in pyrite aqueous suspensions. Results show that adenine oxidizes in the presence of pyrite (without the addition of hydrogen peroxide) and that the rate of oxidation is dependent on the pyrite loading. Adenine oxidation was prevented by addition of either catalase or ethanol to the pyrite/adenine suspensions, which implies that hydrogen peroxide and hydroxyl radicals are causing the adenine oxidation. The adenine oxidation products, 8-oxoadenine and 2-hydroxyadenine, were the same whether hydroxyl radicals were generated by Fenton or pyrite-initiated reactions. Although nucleic acid bases are unlikely to be directly exposed to pyrite particles, the formation of ROS in the vicinity of cells may lead to oxidative stress.  相似文献   

Pyrite oxidation inhibition by a cross-linked lipid coating     

Xiang?Zhang  Michael?J?Borda  Martin?AA?Schoonen  Daniel?R?StronginEmail author 《Geochemical transactions》2003,4(1):8

The effect of a diacetylene-containing phospholipid on the oxidation of pyrite, FeS₂, was investigated. Earlier work reported by our research group showed that the adsorption of l,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine on pyrite suppressed the extent of its oxidation by about 75% over a specific time period. Results presented here show that the pre-exposure to UV radiation of this lipid after sorption onto pyrite results in a 90% suppression. Attenuated total reflection (ATR) Fourier transform infra-red spectroscopy (FTIR) suggests that the UV irradiation of the lipid does not result in degradation of the adsorbed layer. It is believed that the UV exposure results in the cross-linking and polymerization of the adsorbed phospholipid into a relatively impermeable barrier that separates the pyrite from the aqueous phase. The results of this study might have implications for the protection of pyrite from oxidation in the environment.  相似文献   

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park,Wyoming, USA. III. An anion-exchange resin technique for sampling and preservation of sulfoxyanions in natural waters     

Greg?K?Druschel  Martin?AA?SchoonenEmail author  D?Kirk?Nordstrom  James?W?Ball  Yong?Xu  Corey?A?Cohn 《Geochemical transactions》2003,4(1):12

A sampling protocol for the retention, extraction, and analysis of sulfoxyanions in hydrothermal waters has been developed in the laboratory and tested at Yellowstone National Park and Green Lake, NY. Initial laboratory testing of the anion-exchange resin Bio-Rad™ AG1-X8 indicated that the resin was well suited for the sampling, preservation, and extraction of sulfate and thiosulfate. Synthetic solutions containing sulfate and thiosulfate were passed through AG1-X8 resin columns and eluted with 1 and 3 M KCl, respectively. Recovery ranged from 89 to 100%. Comparison of results for water samples collected from five pools in Yellowstone National Park between on-site IC analysis (U.S. Geological Survey mobile lab) and IC analysis of resin-stored sample at SUNY-Stony Brook indicates 96 to 100% agreement for three pools (Cinder, Cistern, and an unnamed pool near Cistern) and 76 and 63% agreement for two pools (Sulfur Dust and Frying Pan). Attempts to extract polythionates from the AG1-X8 resin were made using HCl solutions, but were unsuccessful. Bio-Rad™ AG2-X8, an anion-exchange resin with weaker binding sites than the AG1-X8 resin, is better suited for polythionate extraction. Sulfate and thiosulfate extraction with this resin has been accomplished with KCl solutions of 0.1 and 0.5 M, respectively. Trithionate and tetrathionate can be extracted with 4 M KCl. Higher polythionates can be extracted with 9 M hydrochloric acid. Polythionate concentrations can then be determined directly using ion chromatographic methods, and laboratory results indicate recovery of up to 90% for synthetic polythionate solutions using AG2-X8 resin columns.  相似文献   

Early Cretaceous age of regional metamorphism of the Stanovoi group in the Dzhugdzhur-Stanovoi foldbelt: Geodynamic implications     

A. M. Larin  E. B. Sal&#;nikova  A. B. Kotov  V. A. Glebovitsky  S. D. Velikoslavinsky  A. A. Sorokin  S. Z. Yakovleva  A. M. Fedoseenko  I. V. Anisimova 《Doklady Earth Sciences》2006,409(5):727-731

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Strong Paleoearthquakes along the Aksuu Border Fault according to the Results of Dating the Offset Terrace Complex of the Chon-Aksuu River,Northern Tien Shan     

A. M. Korzhenkov  J. R. Arrowsmith  C. J. Crosby  B. Guralnik  E. A. Rogozhin  A. A. Sorokin  S. V. Abdieva  A. B. Fortuna  A. S. Yudakhin  A. R. Agatova  E. V. Deev  J. V. Mazeika  M. V. Rodkin  J. Shen 《Izvestiya Physics of the Solid Earth》2018,54(2):252-268

The study and radiocarbon dating of the low alluvial terraces of the Chon-Aksuu River, in the Northern Issyk-Kul region, which were broken by the Kebin (Kemin) earthquake of 1911 (Ms = 8.2, Io = 10 to 11), are carried out. The obtained radiocarbon dated ages refer to the second half of the Holocene. Since that time, at least eight strong earthquakes took place along this (Chon-Aksuu) segment of the Aksuu border fault. Three seismic events, including the earthquake of 1911 occurred in the second millennium A.D. This outburst of seismic energy was preceded by two millennia of seismic quiescence, which set in after another pulse of seismic activation. The latter lasted for 1.5 millennia and included five strong earthquakes. The recurrence period of seismic events during the activations is 300–600 years. Hence, the seismic regime along the Chon–Aksuu segment of the Aksuu border fault in the second half of the Holocene was a succession of two seismic activations, each with a duration of 1.0–1.5 ka, which were separated by a 2-ka interval of seismic quiescence. Therefore, the absolute datings of the river terraces of different ages which have been broken by a seismogenic rupture can serve as a reliable source of information about the age of the strong earthquakes that occurred along the seismogenic fault.  相似文献   

The First Evidence of Cambrian Granitoid Magmatism during the Formation History of the Bureya Continental Massif of the Central Asian Fold Belt     

Ovchinnikov  R. O.  Sorokin  A. A.  Kudryashov  N. M. 《Doklady Earth Sciences》2020,493(1):490-494

Doklady Earth Sciences - The results of U–Pb geochronological studies of Early Paleozoic granitoids from the northern part of the Bureya continental massif are presented. It has been...  相似文献