Gypsum solubility in water at 25°C     

A. L. Lebedev  V. L. Kosorukov 《Geochemistry International》2017,55(2):205-210

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Quaternary tectonics of recent basins in northwestern Armenia     

V. G. Trifonov  E. A. Shalaeva  L. Kh. Saakyan  D. M. Bachmanov  V. A. Lebedev  Ya. I. Trikhunkov  A. N. Simakova  A. V. Avagyan  A. S. Tesakov  P. D. Frolov  V. P. Lyubin  E. V. Belyaeva  A. V. Latyshev  D. V. Ozherelyev  A. A. Kolesnichenko 《Geotectonics》2017,51(5):499-519

New data on the stratigraphy, faults, and formation history of lower to middle Pleistocene rocks in Late Cenozoic basins of northwestern Armenia are presented. It has been established that the low-mountain topography created by tectonic movements and volcanic activity existed in the region by the onset of the Pleistocene. The manifestations of two geodynamic structure-forming factors became clear in Pleistocene: (i) collisional interaction of plates due to near-meridional compression and (ii) deep tectogenesis and magma formation expressed in the distribution of vertical movements and volcanism. The general uplift of the territory, which was also related to deep processes, reached 350–500 m in basins and 600–800 m in mountain ranges over the last 0.5 Ma. The early Pleistocene (~1.8 Ma) low- and medium-mountain topography has been reconstructed by subtraction of the latest deformations and uplift of the territory. Ancient human ancestry appeared at that time.  相似文献   

Early Pleistocene magmatism in the central part of the Greater Caucasus     

V. A. Lebedev  O. Z. Dudauri  Yu. V. Gol’tsman 《Doklady Earth Sciences》2017,477(1):1265-1269

An isotope-geochronological study of young magmatism in the central part of the Greater Caucasus (Kazbek neovolcanic area) on the territory of Russia and Georgia has been carried out. It was proved for the first time that, in the Early Pleistocene, there was a separate impulse of magmatic activity in this area. The area of endogenic activity for the period identified was contoured on the basis of the integrated isotope-geochronological, petrological-geochemical, and geological data. It has been shown that the Early Pleistocene volcanism inherits the area of Neogene volcanism in the Kazbek region and, therefore, presents the final impulse of the second (Pliocene) stage of the Late Cenozoic magmatism. Thus, Early Pleistocene volcanism was not a precursor of Late Quaternary magmatism as the latter has other spatial patterns of the location of volcanic centers.  相似文献   

Age and sources of matter for the Kedrovskoe gold deposit,Northern Transbaikal tegion,Republic of Buryatia: Geochronological and isotopic geochemical constraints     

A. V. Chugaev  O. Yu. Plotinskaya  I. V. Chernyshev  V. A. Lebedev  E. V. Belogub  Yu. V. Goltsman  Yu. O. Larionova  T. I. Oleinikova 《Geology of Ore Deposits》2017,59(4):281-295

The paper presents new geochronological and isotopic geochemical data on gold mineralization of the Kedrovskoe deposit. The deposit is located in the northeastern part of the Transbaikal metallogenic province, Russia’s largest. The Early Permian age (273 ± 4 Ma) of mineralization based on the results of Rb–Sr study of metasomatic rocks is correlated with the age of the final phases of Hercynian magmatism in the Baikal–Muya Foldbelt. The Sr, Nd, and Pb isotopic geochemical characteristics of mineralization show that the host rocks are involved in the formation of the latter. It has been established that ore lead was supplied to the hydrothermal system of the deposit mainly from a geochemical reservoir represented by the Neoproterozoic juvenile continental crust of the Baikal–Muya Foldbelt.  相似文献   

The quaternary volcanic rocks of the Geghama highland, Lesser Caucasus, Armenia: Geochronology, isotopic Sr-Nd characteristics, and origin     

V. A. Lebedev  I. V. Chernyshev  K. N. Shatagin  S. N. Bubnov  A. I. Yakushev 《Journal of Volcanology and Seismology》2013,7(3):204-229

This paper reports on isotope-geochronologic, petrologic, and isotope-geochemical (Sr-Nd) studies of Quaternary magmatism in the Geghama neovolcanic area, Armenia, Lesser Caucasus. According to these studies, the period of youngest volcanic activity in the region lasted about 700 000 years, from 700 ka to a few tens of thousands of years ago. We found the time limits of five discrete phases of Quaternary volcanism: I (about 700 ka), II (550?480 ka), III (190?150 ka), IV (110?70 ka), and V (later than 50 ka). These phases seem to have lasted a few tens of thousands of years and were separated by quiescent periods of comparable durations. The petrologic and isotope-geochemical characteristics of Geghama effusive rocks show that they belong to the bimodal association rhyolite-trachyandesite and basaltic trachyandesite; this association was largely generated by fractional crystallization of primary basite melts, with the assimilation of crustal material by deep magmas being much less important. The isotopic parameters of the volcanic rocks studied here (0.70410–0.70437 for ⁸⁷Sr/⁸⁶Sr and +3.3 to +4.0 for ?_Nd) are practically identical for intermediate to basic and acid varieties in this association and are similar to those for young basites in the other areas of the Lesser Caucasus; this circumstance indicates a common origin for all Quaternary magmatic formations in the region. The petrogenesis of these varieties probably involved a single mantle source of the OIB type with certain regional peculiarities in the composition of the melts it generated. An analysis of the locations of Quaternary volcanoes in central Armenia (Geghama and Aragats areas) and in the Kars plateau, which is adjacent to it in the west, provided evidence of an eastward lateral migration of youngest magmatic activity in the region over time. The latest episodes of this migration took place in the eastern Geghama area, which must be the first to produce eruptions in the future.  相似文献   

Experimental estimation of velocities and anisotropy of a series of Swedish crystalline rocks and ores     

Alireza Malehmir  Magnus Andersson  Maxim Lebedev  Milovan Urosevic  Vassili Mikhaltsevitch 《Geophysical Prospecting》2013,61(1):153-167

To provide a guide for future deep (<1.5 km) seismic mineral exploration and to better understand the nature of reflections imaged by surface reflection seismic data in two mining camps and a carbonatite complex of Sweden, more than 50 rock and ore samples were collected and measured for their seismic velocities. The samples are geographically from the northern and central parts of Sweden, ranging from metallic ore deposits, meta‐volcanic and meta‐intrusive rocks to deformed and metamorphosed rocks. First, ultrasonic measurements of P‐ and S‐wave velocities at both atmospheric and elevated pressures, using 0.5 MHz P‐ and S‐wave transducers were conducted. The ultrasonic measurements suggest that most of the measured velocities show positive correlation with the density of the samples with an exception of a massive sulphide ore sample that shows significant low P‐ and S‐wave velocities. The low P‐ and S‐wave velocities are attributed to the mineral texture of the sample and partly lower pyrite content in comparison with a similar type sample obtained from Norway, which shows significantly higher P‐ and S‐wave velocities. Later, an iron ore sample from the central part of Sweden was measured using a low‐frequency (0.1–50 Hz) apparatus to provide comparison with the ultrasonic velocity measurements. The low‐frequency measurements indicate that the iron ore sample has minimal dispersion and attenuation. The iron ore sample shows the highest acoustic impedance among our samples suggesting that these deposits are favourable targets for seismic methods. This is further demonstrated by a real seismic section acquired over an iron ore mine in the central part of Sweden. Finally, a laser‐interferometer device was used to analyse elastic anisotropy of five rock samples taken from a major deformation zone in order to provide insights into the nature of reflections observed from the deformation zone. Up to 10% velocity‐anisotropy is estimated and demonstrated to be present for the samples taken from the deformation zone using the laser‐interferometery measurements. However, the origin of the reflections from the major deformation zone is attributed to a combination of anisotropy and amphibolite lenses within the deformation zone.  相似文献   

Remote assessment of the highest river water level in the absence of hydrometric observations     

V. V. Lebedev  E. I. Kupriyanova  V. N. Orlyankin 《Doklady Earth Sciences》2012,445(1):853-856

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Crystalline complexes of the Tarbagatai block of the Early Caledonian superterrane of Central Asia     

I. K. Kozakov  A. M. Kozlovsky  V. V. Yarmolyuk  V. P. Kovach  E. V. Bibikova  T. I. Kirnozova  Yu. V. Plotkina  N. Yu. Zagornaya  M. M. Fugzan  Ch. Erdenejargal  V. I. Lebedev  G. Eenjin 《Petrology》2011,19(4):426-444

The oldest crystalline complexes of the Early Caledonian superterrane of Central Asia were formed in the Early Precambrian. They are exposed in the basement of microcontinents, which represent old cratonic fragments. Among the latters are the crystalline complexes of the Tarbagatai block previously ascribed to the Dzabkhan microcontinent. It was shown that the crystalline complexes of the Tarbagatai block have a heterogeneous structure, consisting of the Early Precambrian and later Riphean lithotectonic complexes. Structurally, the Early Precambrian complexes are made up of tectonic sheets of gneisses, migmatites, and gneiss granites of the Ider Complex that are cut by gabbroanorthosite massif. The Riphean Jargalant Complex comprises alternating hornblende crystalline schists and biotite (sometimes sillimanite-bearing) gneisses with marble horizons. The upper age boundary of the Riphean Complex is determined by the subautochthonous granitoids with age about 810 Ma. The presence of the Riphean high-grade rocks indicates that structures with newly formed crust were formed in the paleooceanic framing of the Early Precambrian blocks of the Rodinia supercontinent by the Mid-Late Riphean. Divergence that began at that time within old Rodinian cratons and caused rifting and subsequent break-up of the supercontinent was presumably changed by convergence in the paleooceanic area.  相似文献   

Initial time and duration of quaternary magmatism in the Aragats neovolcanic area (Lesser Caucasus,Armenia)     

V. A. Lebedev  I. V. Chernyshev  A. I. Yakushev 《Doklady Earth Sciences》2011,437(2):532-536

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Pliocene ignimbrites of the Elbrus area in the Neogene-Quaternary volcanism history within the Greater Caucasus (isotope-geochronological data)     

Chernyshev  I. V.  Lebedev  V. A.  Bubnov  S. N.  Gol’tsman  Yu. V.  Bairova  E. D. 《Doklady Earth Sciences》2011,436(1):102-107

Doklady Earth Sciences -  相似文献