Lithology and stratigraphy of the Ordovician facies complexes of Gornyi Altai     

V. N. Korzhnev 《Lithology and Mineral Resources》2008,43(6):596-602

In the Ordovician time, the transform margin of the Gornyi Altai region consisted of two bathymetric stages: (1) shelf and upper parts of continental slope; (2) foothills and lower parts of continental slope. The first stage includes the shallow-water facies complexes (terrigenous and terrigenous-carbonate schlieren and variegated flyschoid), while the second stage is composed of deep-water (black shale terrigenous) and subflysch gray (carbonate terrigenous) complexes. Model series of the facies complexes established in our work should be taken into account during the geodynamic analysis of fold zones.  相似文献   

Petrochemistry of the Paleoproterozoic Udokan copper-bearing sedimentary complex     

B. N. Abramov 《Lithology and Mineral Resources》2008,43(1):37-43

The maturity of terrigenous material of the Paleoproterozoic Udokan copper-bearing sedimentary complex is considered. The average values of hydrolyzate module (HM), alumina-silica module (AM), and Pettijohn’s coefficient of maturity appreciably vary throughout the Udokan Complex. Among cupriferous sandstones, rocks of the Aleksandrovka Formation are characterized by the highest maturity, whereas rocks of the Chitkanda Formation are distinguished by the lowest maturity. The maturity of cupriferous sandstones of the Sakukan Formation corresponds to that of host rocks. The maturity of cupriferous sandstones from the Aleksandrovka Formation is much higher than that of host rocks. In the Chitkanda Formation, the cupriferous sandstones are much less mature than host rocks. Climatic conditions in provenances estimated from the Nesbitt index of chemical weathering or chemical index of alteration (CIA) may be characterized as temperate ones without prominent climatic features. Most CIA values range from 46 to 66. The formation of copper-bearing sediments was closely related to the periods of volcanic activity.  相似文献   

Glauconite from Paleogene volcano-terrigenous rocks in Western Kamchatka     

A. R. Geptner  T. A. Ivanovskaya  E. V. Pokrovskaya  N. P. Kuralenko 《Lithology and Mineral Resources》2008,43(3):228-249

It is shown that glauconite-bearing interbeds are widespread in the layer-by-layer studied sections on the Sea of Okhotsk coast (Mainach section) and Kheisliveem River valley (Kavran section), the volcanoterrigenous rocks of the Kovachin, Amanin, and Gakkhin formations of the Paleogene in western Kamchatka (Upper Eocene-Lower Oligocene boundary beds). Detailed mineralogical and structural-crystallochemical characteristics of glauconite from the Amanin Formation are presented. It is suggested that such glauconite should not be used for geochronological purposes.Some specific features of glauconite formation, particularly, the preservation of specific morphological forms at high accumulation rates of volcano-terrigenous rocks, are discussed. Possibility of the formation of glauconite with the active influence of bacterial metabolism is considered.  相似文献   

The 45th anniversary of the journal <Emphasis Type="Italic">Lithology and Mineral Resources</Emphasis>     

V. N. Kholodov 《Lithology and Mineral Resources》2008,43(4):303-306

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Some types of small clinoforms in latest continental deposits     

G. F. Ufimtsev 《Lithology and Mineral Resources》2008,43(1):76-80

Some rare types of small clinoforms found in the latest continental deposits of lowland platform and mountain regions are described. The clinoforms are represented by prodelta deposits of mountain lakes, oblique-bedded horizons of floodplain alluvium of strongly meandering rivers, thick and short lenses of mountain alluvium, and alluvium horizons of great lowland rivers with oblique bedding grading into horizontal bedding. Such structures bear information on paleogeographic, morphological, and lithodynamic features of continental sedimentation.  相似文献   

Silica phase transformations in the petroliferous sequences     

Yu. K. Burlin  I. I. Plyusnina 《Moscow University Geology Bulletin》2008,63(3):154-161

The joint evolution of organic matter and silica in petroliferous sequences is considered in the terms of the laws of transformation of dispersion systems. The dispersion systems are transformed under conditions of low-temperature solid-phase processes accompanied by the silica phase transition and dehydration that favors the evolution of organic matter.  相似文献   

Age of the Earth’s crust and the Nd isotopic composition of the mantle sources of East Antarctic complexes     

E. V. Mikhalsky 《Geochemistry International》2008,46(2):168-174

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Composition, P-T parameters, and metasomatic transformations of mafic schists of the Svyatoi Nos Peninsula, Eastern Baikal Area     

V. A. Makrygina  Z. I. Petrova  A. A. Koneva  L. F. Suvorova 《Geochemistry International》2008,46(2):140-155

The paper reports data on rock and mineral compositions from the Svyatonosskaya Formation, which is a continuation of the Ol’khon Series in the northern part of the Svyatoi Nos Peninsula, eastern shore of Lake Baikal. The pyroxene-amphibole-plagioclase schists (metagabbro) are replaced there by the garnet-biotite-quartz assemblage, which was formed, according to the data of various geothermometers and calculations by the THERMOCALC computer program, under conditions corresponding to the transition from the granulite (848–811°C) to high grades of the amphibolite (715–670°C) facies under high pressures (8.7 ±1.6 kbar). In petrogenetic grids, these conditions fall onto the line of the onset of eclogitization. In nature these rocks are a continuation of the Chernorudskaya-Barakchinskaya zone of elevated pressures in the Ol’khon area. The metasomatic rocks were formed simultaneously with strike-slip faulting, when coupled zones of relatively high-(eclogite-like) and low-pressure (quartzite-marble melange) developed at the inflow of SiO₂ and K₂O and the removal of MgO and CaO. Analogous compositional changes in gneisses and schists in tectonic extension zones in Ol’khon Island and neighboring areas occurred during the development of migmatites. The migmatization of the gneisses was likely coupled with the garnetization of mafic schists in high-pressure zones and the formation of eclogite-like rocks replacing marbles. The accompanying graphitization of this block suggests that the metasomatic fluid had a hydrocarbon-hydrogen composition.  相似文献   

Diamond formation in sulfide pyrrhotite-carbon melts: Experiments at 6.0–7.1 GPa and application to natural conditions     

A. V. Shushkanova  Yu. A. Litvin 《Geochemistry International》2008,46(1):37-47

Experiments at 6.0–7.1 GPa and 1500–1700°C were carried out to explore the boundary conditions of diamond nucleation and growth in pyrrhotite-carbon melt-solutions. Pyrrhotite is one of the main sulfide minerals of the pyrrhotite-pentlandite-chalcopyrite assemblage of mantle rocks and primary inclusions in diamond. Solutions of carbon in sulfide melts oversaturated with respect to diamond at the expense of the dissolution of starting graphite (thermodynamically unstable phase) are formed owing to the difference between the solubilities of graphite and diamond, which increases under the influence of temperature gradients in experimental samples. We determined the fields of carbon solutions in pyrrhotite melt showing labile and metastable oversaturation with respect to diamond, which correspond to the spontaneous nucleation of the diamond phase and diamond growth on seeds, respectively. The linear growth rate of diamond in sulfide-carbon melts is rather high (on average, 10 μ/min during the first 1–2 min from the onset of spontaneous crystallization). The nucleation density is estimated as 180 grains per cubic centimeter. Diamonds crystallized from sulfide melts show octahedral and spinel twin shapes. Diamond polycrystals were synthesized for the first time from a sulfide medium as intergrowths of skeletal (edge) or “cryptocrystalline” microdiamonds, from 1 to 100 μm in size, their spinel twins and, occasionally, polysynthetic (star-shaped) twins. During diamond growth from sulfidecarbon melts on smooth faces of cuboctahedral diamond seeds synthesized in metal systems, smooth-faced layer-by-layer step-like growth was observed on their octahedral (111) faces, whereas growth on the (100) cubic faces produced rough-surfaced layers of intergrown micropyramids, whose axes were oriented normal to the (100) face. The obtained experimental results were applied to the problem of diamond genesis under the conditions of the Earth’s mantle in the framework of the model of carbonate-silicate parental melts with blebs of immiscible sulfide melts.  相似文献   

Chemical composition of atmospheric precipitates within the influence zone of the Severonikel Smelter   总被引：1，自引：1，他引：0  

V. A. Dauval’ter  M. V. Dauval’ter  N. V. Saltan  E. N. Semenov 《Geochemistry International》2008,46(10):1064-1069

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