Bacterial genesis of calcium phosphates in human organism and nature     

L. G. Gilinskaya  Yu. N. Zanin  N. A. Rudina 《Lithology and Mineral Resources》2007,42(1):56-67

Comparison of natural marine (nodular and granular) carbonate-apatites and pathogenic mineral structures formed in human cardiac valves by methods of scanning electron and high-resolution transmission microscopy revealed common morphological features corresponding to the bacterial origin of calcium phosphates. These features may be considered typomorphic ones regardless of their formation environments (in vivo or in nature).  相似文献   

New data on the age of subalkaline magmatism at the eastern margin of the east European paleocontinent and estimation of the rate of longitudinal opening of the early Paleozoic rift     

G. A. Petrov  Yu. L. Ronkin  A. V. Maslov 《Doklady Earth Sciences》2007,414(4):542-547

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Relationships between the chemical and isotopic (Sr,Nd, Hf,and Pb) heterogeneity of the mantle     

Yu. A. Kostitsyn 《Geochemistry International》2007,45(12):1173-1196

The reasons for the isotopic heterogeneity of the mantle are analyzed in this paper on the basis of published isotopic data. It was shown that the observed variations in the Sr, Nd, Hf, and Pb isotopic compositions of oceanic basalts cannot be explained by mixing of a finite number of homogeneous reservoirs (components). The considerable variations in the contents of Rb, Sr, Sm, Nd, Lu, Hf, U, Th, and Pb and ratios of these and other trace elements in tholeiitic basalts indicate that the chemical heterogeneity of mantle-derived rocks is inherited in part from their sources. Oceanic tholeiitic basalts show a tight correlation between the variances of Nd, Hf, Sr, and Pb isotopic ratios and the variances of respective radiogenic additions that could be accumulated in these rocks over a time period of 〈t〉 = 1.8 Gyr. This paradox clearly indicates that variations in all the mentioned isotopic systems in the mantle cannot be understood without the analysis of the geochemical heterogeneity of rocks.The close to lognormal distributions of lithophile trace elements in oceanic tholeiitic basalts and the character of correlations between them suggest that magmatic differentiation was the major mechanism of the formation of chemical heterogeneity in the mantle. The role of metasomatism in the global transport of trace elements and formation of the geochemically heterogeneous mantle is probably rather limited. Intrusive processes within the mantle could result in the development of chemical and, after a period of time, isotopic anomalies in the mantle. Simple calculations show that long-lived geochemical anomalies related to alkaline magmatism could be responsible for EM-I type isotopic anomalies, and geochemical anomalies produced in the mantle by enriched tholeiitic melts could be sources of EM-II type isotopic anomalies. The analysis of the distribution of the isotopic compositions of mantle-derived igneous rocks in various “isochron” coordinates suggested that the formation of geochemical anomalies in the mantle is a long-term process lasting for hundreds of millions of years. Nonetheless, trends approaching 4.5 Ga were never observed in such diagrams, i.e., the mantle is in general rejuvenated in all isotopic systems. Both on global and local scales, there are no mantle domains that have remained geochemically closed and isolated since the Earth’s formation. The entire mantle is involved in material exchange processes.The development of isotopic systems in the mantle was explored by means of statistical modeling accounting for the tendency of a continuous increase in the chemical heterogeneity of the mantle source and the tendency of obliteration of the isotopic heterogeneity owing to the convective mixing in the mantle. The modeling demonstrated that the character of the isotopic heterogeneity of the mantle is statistically consistent with the character of its chemical heterogeneity. The mantle isotopic anomalies HIMU, EM-I, and EM-II were generated by two simultaneous processes: the magmatic differentiation of mantle material and its not very efficient mixing.  相似文献   

The dynamics of the shock disruption of interstellar clouds     

E. E. Matvienko  Yu. A. Shchekinov 《Astronomy Reports》2007,51(2):109-118

The effect of the structural irregularity of an interstellar cloud on the dynamics of its disruption by a shock from a supernova is studied. Irregular clouds are disrupted twice as fast as spherical clouds. However, fragments of irregular clouds preserve their enhanced density for long times without being mixed with the intercloud gas. The fraction of shock energy that is converted to the kinetic energy of the fragments is 50% higher than in the disruption of a spherical cloud. Shocks are not able to trigger the gravitational compression of clouds.  相似文献   

Tracing infiltration and recharge using stable isotope in Taihang Mt., North China   总被引：3，自引：0，他引：3  

Fadong Li  Xianfang Song  Changyuan Tang  Changming Liu  Jingjie Yu  Wanjun Zhang 《Environmental Geology》2007,53(3):687-696

The groundwater in headwater region is an important recharge source for the adjacent mountain-front plain. In order to reveal the relationship among precipitation, soil water and groundwater, from June to September in 2004, stable isotopes (deuterium and oxygen-18) in precipitation and soil waters at the depths of 10, 20, 30, 50, 70, 90, and 110 cm were analyzed at two sites covered by black locust (Robinia Pseudoacia L.) (Site A) and grass predominated by Themeda triandra (T. japonica (Willd.) Tanaka) and Bothriochloa ischaemum (B. ischaemum (L.) Keng) (Site B) in an experimental catchment at Taihang Mt., North China, respectively. The δ¹⁸O of precipitation in daily rain events shows large variations (−13.3 to −4.3‰) with a mean of 8.1‰. The δ¹⁸O and δ D of soil waters along profiles in two sites suggest that the influence of canopy cover was just up to 10 cm in top soil water. The soil water moved over the zero flux plane at 70 cm in-depth is expected to escape the evaporative effect at the end of September in both sites. The results show that the stable isotope, instead of tritium as tradition, can be used to trace the soil water behaviors based on the movement of isotopic peak along the vertical profiles in this semi-arid and semi-humid mountainous region. The infiltration depths of soil water in Taihang Mt. are 12 and 10 mm/day from June to September in 2004 in Site A and Site B, respectively. Tracing by stable isotope, recharge fluxes of soil water to local groundwater are of 3.8 and 3.2 mm/day in Site A and Site B, respectively. The results provide desirable information for assessment of local groundwater resources. An erratum to this article can be found at  相似文献   

Low-temperature heat capacity and thermodynamic properties of natural polylithionite     

I. E. Paukov  Yu. A. Kovalevskaya  I. A. Kiseleva  T. N. Shuriga  V. N. Ikorskii 《Geochemistry International》2007,45(9):926-930

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黔西北地区典型铅锌矿床地质特征分析及找矿思路     

余未来  范良伍 《矿物学报》2007,27(3):461-465

通过归纳黔西北地区的区域地质背景，典型矿床的地质特征，比较矿床中矿石和含矿地层的Pb／盈比值和REE配分模式，分析构造展布、矿床（点）的分布和物探异常之间的关系，提出构造是区域的主要控矿因素，从而强调研究构造体系是综合找矿工作的重点。  相似文献   

青藏高原DEM的生成与应用     

邢宇  姜琦刚  王坤  程彬  李远华  王耿明  张红红 《世界地质》2007,26(4):479-483

数字高程模型（DEM）不仅可以实现三维地形可视化，而且还能由其进一步获得与高程有关的地形要素。针对青藏高原DEM生成和应用过程中碰到的数据量大、区域广阔、应用难度大等问题，本文给出了相应的解决方案，提出一套DEM制作和应用流程：以1：25万地形图矢量等高线数据内插方式生成青藏高原DEM数据，在此基础上，运用Mask处理后相交分析思想与多级金字塔、DEM水淹分析、高程分带等处理技术实现了青藏高原三维地形可视化、三维遥感影像制作、及其它生态地质环境因素的变化分析。基于此方法生成的青藏高原DEM数据，不仅精度高，三维地形可视化效果好，而且解决了海量DEM数据与其它资料综合分析的问题。  相似文献   

Latitudinal activation of magmatism as a response to cyclic tidal evolution in the Earth-Moon-Sun system     

Yu. N. Avsyuk  A. Ya. Saltykovsky  Yu. S. Genshaft 《Doklady Earth Sciences》2007,413(2):178-179

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The 40th Tectonic Conference of the Interagency Tectonic Committee,Division of Earth Sciences,Russian Academy of Sciences     

Yu. V. Karyakin 《Geotectonics》2007,41(4):333-336

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