Diamonds in the products of the 2012–2013 Tolbachik eruption (Kamchatka) and mechanism of their formation     

E. M. Galimov  G. A. Karpov  V. S. Sevast’yanov  S. N. Shilobreeva  A. P. Maksimov 《Geochemistry International》2016,54(10):829-833

The origin of diamonds in the lava and ash of the recent Tolbachik eruption of 2012–2013 (Kamchatka) is enigmatic. The mineralogy of the host rocks provides no evidence for the existence of the high pressure that is necessary for diamond formation. The analysis of carbon isotope systematics showed a similarity between the diamonds and dispersed carbon from the Tolbachik lava, which could serve as a primary material for diamond synthesis. There are grounds to believe that the formation of Tolbachik diamonds was related to fluid dynamics. Based on the obtained results, it was suggested that Tolbachik microdiamonds were formed as a result of cavitation during the rapid movement of volcanic fluid. The possibility of cavitation-induced diamond formation was previously theoretically substantiated by us and confirmed experimentally. During cavitation, ultrahigh pressure is generated locally (in collapsing bubbles), while the external pressure is not critical for diamond synthesis. The conditions of the occurrence of cavitation are rather common in geologic processes. Therefore, microdiamonds of such an origin may be much more abundant in nature than was supposed previously.  相似文献   

Provenance analysis for Middle Eocene sediments in the West Kamchatka sedimentary basin (Tigil area)     

A. I. Khisamutdinova  A. V. Solov’ev  D. V. Rozhkova 《Lithology and Mineral Resources》2016,51(4):310-332

The paper presents the results of reconstruction of Middle Eocene provenances for the West Kamchatka sedimentary basin (WKSB) corresponding to the Tigil area. It has been established that the early (Eocene) evolution stage of WKSB was marked by the deposition of terrigenous sediments in intermontane depressions followed by the accumulation of shallow-marine sediments after transgression. In terms of the composition, sandstones of the Middle Eocene Snatol Formation correspond to graywackes. With respect to the geochemistry of sandstones, their provenances were confined to an active continental margin and island arc. The mineral composition of the heavy fraction suggests an alternating dominance of felsic and mafic rocks in the provenances. Dating of the clastic zircon from sandstones of the Snatol Formation by the LA-ICP-MS method revealed a wide variation range of their age. The most significant peak is close to the age of calc-alkaline magmatism in the Okhotsk–Chukotka volcanic belt. This fact provides insight into the Eocene paleogeography: the major rock provenances were located in the Okhotsk–Chukotka volcanic belt and the eastern Achaivayam–Valagin island arc. Local sources of clastic material were represented by the Utkholok and Kinkil volcanic belts.  相似文献   

Some general relations of the development of complex molecular objects at early stages of biosphere formation as a consequence of the physical properties of condensed medium     

V. I. Baranov  L. A. Gribov  V. A. Dement’ev  I. V. Mikhailov 《Geochemistry International》2016,54(11):1011-1018

We analyzed the character of molecular transformations under conditions of condensed media, in which intermolecular interactions always occur. It was shown that, instead of discrete transfer of external energy into the molecule, the energy characteristics of the condensed medium (appearance of zones) could result in gradual accumulation of internal energy in reaction centers owing to sequential thermal collisions with particles of the medium initiating the chemical reaction. This does not require high temperatures. The established physical properties related to the energy characteristics of condensed media could play an important role in molecular transformations and, consequently, formation of complex molecular objects at early stages of biosphere formation.  相似文献   

Geochemistry and petrogenesis of the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan marginal seas     

T. A. Emel’yanova  E. P. Lelikov 《Geochemistry International》2016,54(6):509-521

The results of ICP-MS trace-element (LILE, HFSE, REE) study of the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and geochronological K-Ar dating of the Eocene volcanic rocks are presented. Specifics of volcanism developed on submarine rises of these seas was characterized for the first time, and magma sources and geodynamic settings of the volcanic complexes predating the formation of the deep-water basins were determined. It is established that the Late Mesozoic magmas were formed in a subduction setting from spinel peridotites of suprasubduction mantle wedge, which was metasomatically reworked by aqueous fluids that were released by dehydration of sedimentary layer of subducting oceanic plate. This follows from the elevated concentrations of H₂O, alkalis, potassium, LILE and LREE, and lowered HFSE (including Ta-Nb minimum) and HREE contents, at lowered Sm/Yb, Nb/Ta, Nb/Y and elevated La/Nb, Ba/La, and Zr/Y ratios. Eocene adakite-like volcanic rocks were identified for the first time in the Sea of Okhotsk. They vary from andesitic to more felsic compositions with elevated MgO (>4%) and elevated La/Yb (>14) and Sr/Y (50–60) ratios. Identification of adakite-like volcanic rocks serves as evidence in support of the transform continental-margin (or plate sliding) setting, which is characterized by breaking apart of subduction slab and formation of slab “windows” acting as pathways for the transfer of asthenospheric mantle into continental lithosphere. New geochemical data on the Late Mesozoic–Early Cenozoic volcanic rocks of the Okhotsk and Japan seas and analysis of literature data were used to distinguish two geodynamic settings within these seas: subduction and transform margin. Similar settings operated at that time in the adjacent continental- margin volcanic belts (Akinin and Miller, 2011; Martynov and Khanchuk, 2013; et al.).  相似文献   

Mesoscale numerical simulation study of warm fog dissipation by salt particles seeding     

Hui He  Xueliang Guo  Xiang’e Liu  Qian Gao  Xingcan Jia 《大气科学进展》2016,33(5):579-592

Based on the dynamic framework of WRF and Morrison 2-moment explicit cloud scheme, a salt-seeding scheme was developed and used to simulate the dissipation of a warm fog event during 6–7 November 2009 in the Beijing and Tianjin area. The seeding effect and its physical mechanism were studied. The results indicate that when seeding fog with salt particles sized 80 μm and at a quantity of 6 gm~(-2) at the fog top, the seeding effect near the ground surface layer is negative in the beginning period, and then a positive seeding effect begins to appear at 18 min, with the best effect appearing at 21 min after seeding operation. The positive effect can last about 35 min. The microphysical mechanism of the warm fog dissipation is because of the evaporation due to the water vapor condensation on the salt particles and coalescence with salt particles.The process of fog water coalescence with salt particles contributed mostly to this warm fog dissipation. Furthermore, two series of sensitivity experiments were performed to study the seeding effect under different seeding amounts and salt particles sizes. The results show that seeding fog with salt particles sized of 80 μm can have the best seeding effect, and the seeding effect is negative when the salt particle size is less than 10 μm. For salt particles sized 80 μm, the best seeding effect, with corresponding visibility of 380 m, can be achieved when the seeding amount is 30 g m~(-2).  相似文献   

An algorithm to retrieve precipitation with synthetic aperture radar     

谢亚楠  刘志坤  安大伟 《Acta Meteorologica Sinica》2016,30(3):401-411

This paper presents a new type of rainfall retrieval algorithm, called the model-oriented statistical and Volterra integration. It is a combination of the model-oriented statistical (MOS) and Volterra integral equation (VIE) approaches. The steps involved in this new algorithm can be briefly illustrated as follows. Firstly, information such as the start point and width of the rain is obtained through pre-analysis of the data received by synthetic aperture radar (SAR). Secondly, the VIE retrieval algorithm is employed over a short distance to obtain information on the shape of the rain. Finally, the rain rate can be calculated by using the MOS retrieval algorithm. Simulation results show that the proposed algorithm is effective and simple, and can lead to time savings of nearly 50% compared with MOS. An example of application of SAR data is also discussed, involving the retrieval of precipitation information over the South China Sea.  相似文献   

On the dynamics of persistent states and their secular trends in the waveguides of the Southern Hemisphere troposphere     

Terence J. O’Kane  James S. Risbey  Didier P. Monselesan  Illia Horenko  Christian L. E. Franzke 《Climate Dynamics》2016,46(11-12):3567-3597

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Estimation of Aerosol Radiation Effects under Background and Smoke-haze Atmospheric Conditions over Siberia from Empirical Data     

M. V. Panchenko  T. B. Zhuravleva  V. S. Kozlov  I. M. Nasrtdinov  V. V. Pol’kin  S. A. Terpugova  D. G. Chernov 《Russian Meteorology and Hydrology》2016,41(2):104-111

The results of numerical simulation of downward solar radiation fluxes for background and smoke-contaminated atmospheric conditions are discussed. Vertical profiles of aerosol characteristics are obtained from the empirical model based on the data of aircraft sounding of profiles of angular scattering coefficients and content of absorbing particles in the lower troposphere. The background model was created using the results of measurements obtained under cloudless and mostly cloudless atmospheric conditions in 1999–2011. Optical parameters of smoke aerosol are determined from the data of aircraft measurements in the period of long-term wildfires in Siberia in the summer 2012. It is demonstrated that deficiency in diurnal values of total solar radiation at the surface level caused by the formation of the optically dense smoke layer as compared to background conditions, is more than 13 MJ/m².  相似文献   

The Answer to the Comments by Yu. D. Resnyanskii to the Papers by L. Kh. Ingel’ and A. A. Makosko     

. Kh. Ingel’  A. A. Makosko 《Russian Meteorology and Hydrology》2016,41(2):146-150

The critical comments to the publications by the authors ofthe present paper that were given in [10] (the publications deal with the possible effects of gravity field inhomogeneities in the atmosphere and ocean) are discussed. In the authors' opinion, some remarks are groundless. At the same time, the authors agree with one of the important remarks that the results of their paper concerning studies of the ocean disturbances are to be reconsidered.  相似文献   

同化FY3B/IRAS资料对GRAPES分析场影响诊断     

王根  刘文静  唐怀瓯 《气象与环境科学》2016,39(3):15-21

GRAPES(Globe and Regional Assimilation and Prediction System)变分系统能够同化常规资料和非常规卫星资料,这些被同化的资料究竟对同化系统得到的分析场有何影响,目前国内外尚未见相关的研究文献。为此,首次采用基于信息熵信号自由度思想,诊断风云三号B星(FY3B)红外分光计(Infrared Atmospheric Sounder,IRAS)资料对GRAPES分析场的影响。诊断过程中,采用数值逼近方法,统计2012年12月24日18时到2013年1月22日00时共114个时次IRAS资料对GRAPES分析场影响,结果表明,IRAS中高层通道亮温资料对GRAPES分析场影响比地表通道20观测亮温的影响大,地表通道8和9观测亮温对分析场影响较大。前24个GRAPES变分同化时次每个时次IRAS通道亮温对分析场影响的贡献率分析结果显示,高层通道和H_2O通道贡献率较大。个例分析结果表明,在同化探空资料基础上加入IRAS资料后,温度和湿度增量场变化幅度较大,表明IRAS资料对分析场有降温和增湿作用。  相似文献