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Nakamura Hitomi Iwamori Hikaru Morikawa Noritoshi Kharitonova Natalia Chelnokov Georgy Bragin Ivan Chang Qing 《Aquatic Geochemistry》2021,27(4):269-282
Aquatic Geochemistry - Spring waters with high-pCO2 content are widely distributed in the Sikhote-Alin region in Russia. Mukhen spa is one such spring located in the northern Sikhote-Alin region.... 相似文献
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T. G. Ryashchenko N. N. Ukhova S. I. Shtel’makh N. I. Belyanina P. S. Belyanin 《Russian Journal of Pacific Geology》2011,5(3):238-249
This paper addresses the hypotheses of the formation of the brown loams widely spread in the zone with hummocky relief within
the intermontane Razdol’noe-Khanka Depression. These hypotheses were proposed in the 1970s–1980s. The accumulation of information
on the loess formation in southern East Siberia, as well as obtaining new analytical data on the microtextural, mineralogy,
and major and trace-element composition of the brown loams, and the comparative analysis of these deposits provided for the
formulation of a more substantiated view concerning the place of the brown loams in the group of loess-type rocks. 相似文献
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G. V. Nesterenko N. A. Roslyakov S. M. Zhmodik Yu. A. Kalinin N. S. Morozova M. V. Kirillov V. V. Kolpakov D. K. Belyanin S. R. Osintsev 《Lithology and Mineral Resources》2014,49(1):29-46
Study of gold potential of the Late Cenozoic alluvium in the Bauntov area is based on the Taloi basin and Sivo sector (China River basin). Primary placer-forming gold is mainly represented by endogenous varieties. In contrast to alluvium of streams in the Taloi basin, Middle-Upper Quaternary alluvium of the Sivo sector (China River basin) is enriched in fine and tiny gold (smaller than 0.25 mm). The paper presents data testifying to a low Au content in the silt fraction of slimes from boreholes drilled in the Cenozoic alluvium (alluvium-deluvium) from transverse valleys in the Taloi basin and, hence, to an significant manifestation of the chemogenic concentration of this metal therein. Issue of the existence of specific conditions favorable for the formation of hydrogenic gold in the northern high-latitude zones requires further studies. The results show that lithochemical gold aureoles have an important prospecting significance. They also suggest the practical significance of accumulations of fine and tiny gold in the syn-stratal alluvium and alluvium-deluvium of large ore placer areas. 相似文献
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N.A. Roslyakov M.V. Kirillov N.S. Morozova S.M. Zhmodik Yu.A. Kalinin G.V. Nesterenko N.V. Roslyakova D.K. Belyanin V.V. Kolpakov 《Russian Geology and Geophysics》2013,54(5):483-494
Holocene shallow (0.5–4.5 m, rarely more) and Pliocene–Pleistocene deep (> 25 m) placers occur within the China tectonic depression. The shallow placers are associated with the formation of the present-day drainage valleys of the China River under permafrost conditions, and the deep ones are localized within the preglacial paleovalleys of the river basin. An integrated geological and geochemical study was carried out at ten shallow commercial placers, eight of which are classified as poorly studied and “unconventional.” Placers are considered “unconventional” based on their technological characteristics (commercial gold is small (? 0.25 to + 0.1 mm), thin (? 0.1 mm), and micron-sized or “bound” (invisible)), geomorphologic conditions of formation, confinement to the oxidized zone of active permafrost, significant portion of fine hydrogenic gold, and several other minor features.The formation of shallow “unconventional” placers is controlled by the conditions of active permafrost. Under aerobic conditions, suprapermafrost waters form an oxidized zone, in which iron hydroxides impart a yellowish reddish color to water-bearing rocks. Long-lived geochemical barriers (biogenic, reduction, electrochemical, sorption, and others), including gravitational differentiation, play an important role in the concentration of small and thin gold.Alluvial deposits in Meso-Cenozoic tectonic depressions, such as the China basin, are the most promising in terms of “unconventional” placers. The main factors favoring the formation of these localities and the criteria for their assessment are large feeding sources of gold (mainly carbonaceous and sulfide) mineralization, endogenic and exogenic dispersion aureoles with thin and invisible gold; increased thickness of the suprapermafrost active layer and its temporal and spatial stability, contributing to the formation and functioning of oxidized horizons with the accumulation of ferric hydroxide and hydrogenic gold; specific morphologic varieties of hydrogenic gold, which are the fundamental criterion for primary gold mineralization with migratable metal; fine-clastic clay-rich composition of recent alluvial or alluvial-talus sediments, produced by water reworking of ancient gold-bearing weathering crusts; and development of broad floodplains filled with Holocene sediments and their junction with talus-solifluction erosional slopes. 相似文献
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Oleg G. Safonov Elizaveta I. Kovaleva Svetlana A. Kosova H.M. Rajesh Georgy A. Belyanin Maria A. Golunova Dirk D. Van Reenen 《地学前缘(英文版)》2012,3(6):829-841
Reaction textures and fluid inclusions in the～2.0 Ga pyroxene-bearing dehydration zones within the Sand River biotite-hornblende orthogneisses（Central Zone of the Limpopo Complex） suggest that the formation of these zones is a result of close interplay between dehydration process along ductile shear zones triggered by H2O-CO2-salt fluids at 750—800℃and 5.5—6.2 kbar.partial melting,and later exsolution of residual brine and H2O-CO2 fluids during melt crystallization at 650—700℃.These processes caused local variations of water and alkali activity in the fluids,resulting in various mineral assemblages within the dehydration zone.The petrological observations are substantiated by experiments on the interaction of the Sand River gneiss with the H2O-CO-2-（K,Na）Cl fluids at 750 and 800℃and 5.5 kbar.It follows that the interaction of biotite-amphibole gneiss with H2O-CO2-（K.Na）Cl fluids is accompanied by partial melting at 750—800℃.Orthopyroxene-bearing assemblages are characteristic for temperature 800℃and are stable in equilibrium with fluids with low salt concentrations,while salt-rich fluids produce clinopyroxene-bearing assemblages.These observations arc in good agreement with the petrological data on the dehydration zones within the Sand River orthoeneisses. 相似文献
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Georgy Shevchenko Alexander Shishkin Grigory Bogdanov Artem Loskutov 《Pure and Applied Geophysics》2011,168(11):2011-2021
Bottom pressure gauges deployed in bays of Shikotan Island (South Kuril Islands) recently recorded two tsunamis: the Simushir
(Kuril Islands) tsunami of January 13, 2007 generated by a local earthquake with magnitude M
w = 8.1 and the Peruvian tsunami of August 15, 2007 generated by a distant earthquake, M
w = 8.0. The records enabled us to investigate the properties of these two tsunamis and to estimate the effect of the regional
and nearshore topography on arriving tsunami waves. Eigen periods and spatial structure of resonant oscillations in particular
bays were examined based on results of numerical modeling. Significant amplification of the fundamental (Helmholtz) resonant
modes in Malokurilskaya Bay (19 min) and in Krabovaya Inlet (29 min) and some secondary modes was caused by the Simushir tsunami.
The considerably different geometry and bottom topography of these bays, located on the inner coast of the island, determine
the differences in their eigen periods; the only mutual peak, which was found in both basins, had a period of 5 min and was
probably related to the source features. The Peruvian tsunami was clearly recorded by the bottom pressure gauge in Tserkovnaya
Bay on the outer (oceanic) coast of the island. Three dominant periods in the tsunami spectrum at this bay were 60, 30 and
19 min; the latter period was found to be related to the fundamental mode of the bay, while the other two periods appear to
be associated with the shelf resonant amplification of tsunami waves arriving in the region of the South Kuril Islands. The
prevalence of low-frequency components in the observed tsunami spectrum is probably associated with the large extension of
the initial source area and faster decay of short period waves during the long trans-oceanic tsunami propagation. 相似文献