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931.
The C and H isotopic compositions of the methane in more than 160 gas samples from 10 basins in China are presented in this paper.The natural gases are classified as four types: biogenic gas ,bio-thermocatalytic transitional gas, gas associated with condensate oil ,and coal-type gas. The isotopic compositions of these gases closely related to the depositional basins, the types of organic matter,the stages of thermal evolution and the genetic characteristics of different gas reservoirs.Studies of the C and H isotopic compositions of terrigenous natural gases will provide valua-ble information on the prospecting and development of natural gases of different genetic types. 相似文献
932.
An experimental study has been carried out to determine the partition coefficients of tungsten between aqueous fluids and
granitic melts at 800 °C and 1.5 kb with natural granite as the starting material. The effects of the solutions on the partition
coefficients of tungsten show a sequence of P > CO
3
2−
> B > H2O. The effects are limited (generallyK
D
< 0.3) and the tungsten shows a preferential trend toward the melt over the aqueous fluid. The value ofK
D
increases with increasing concentration of phosphorus; theK
D
increases first and then reduces with the concentration of CO
3
2−
when temperature decreases, theK
D
between the solution of CO
3
2−
and the silicate melt increases, and that between the solution of B4O
7
2−
and the silicate melt decreases. The partition coefficients of phosphorus and sodium between fluids and silicate melts have
been calculated from the concentrations of the elements in the melts. TheK
D
value for phosphorus is 0.38 and that for sodium is 0.56. Evidence shows that the elements tend to become richer and richer
in the melts. 相似文献
933.
Types and distribution of silver ore deposits in China 总被引:2,自引:0,他引:2
Silver is generally recovered as a by- and co-product along with Au, Pb, Zn, Cu, Sb, Bi, Hg, Sn and W from polymetallic and
gold mines in China. Chinese silver deposits can be classified into five principal types according to host rocks. These types
and their host rocks are: (1) marine volcanic-sedimentary rocks hosting (la) massive sulfide Pb-Zn-(Cu)-Ag ores and (1b) stratiform
Ag-(Au) ores; (2) continental volcanic-sedimentary rocks containing (2a) various polymetallic-silver veins and/or stockworks,
and (2b) Ag-(Au) veins in pyroclastic rocks; (3) rocks affected by metasomatic processes including (3a) complex Sn-polymetallic-Ag
ores, (3b) Pb-Zn-(Cu)-Ag skarns, (3c) associated W-Ag quartz veins and/or skarns, and (3d) Ag-(Au) zones and veins in altered
carbonate rocks; (4) metamorphic-intrusive rocks, principally Ag-(Au) veins in sheared and brecciated metamorphic rocks; and
(5) sedimentary rocks including (5a) stratiform Pb-Zn-Ag ores in carbonate rocks, (5b) Ag-V mantos in black shales, and (5c)
Cu-(Ag) layers in red sandstones. A sixth grouping includes gossans. The tectonic settings, geological features, and temporal
and spatial distribution of these different types of silver occurrences indicate that silver mineralization reflects to a
great extent the evolution of tectonic environments in China throughout geological time. Type 1 is generally developed in
association with several fold belts from the Caledonian to Yanshanian orogens, while types 2, 3 and 4 correlate with rejuvenation
of the eastern China continent during the Mesozoic period. The three subgroups of type 5 are recognized in different stages
and various sedimentry and diagenetic environments during the development of paraplatforms and fold belts. Type 6 results
from recent weathering of existing sulfide ores or protores.
Editorial handling: DR 相似文献
934.
为了解奂徐集复杂断块地区含油范围预测问题,使用了地震多参数分
析法。多参数分析法是充分利用各种地球物理参数(振幅、频率、相位及
速度等),并将各参数测定结果与地质因素相结合,引用判别函数以判定
其含油性,进而预测早期油水边界。利用地震多参数分析法,在徐集地区
预测早期油水边界已取得了较好的效果。 相似文献
935.
海南岛石碌群中双峰火山岩Sm—Nd同位素特征兼论石碌铁矿成矿背景 总被引:9,自引:1,他引:9
对海南岛石碌群第6层及其相当层位中海相双峰火山岩Sm-Nd同位素,微量和稀土元素的研究表明,位于火山岩带西段军营和石碌的细碧岩具有N-MORB特征,在中段和东段芙蓉田和兰洋的变拉斑玄武岩具有E-MORB和IRT(初始裂谷拉斑玄武岩)特征。石碌群的玄武岩和石碌Fe-Co-Cu矿床分别与红海裂谷中南段的新生代玄武岩和Athantis Ⅱ DeeP多金属矿床有许多相同之处。双峰火山岩的另一端元为壳源型石 相似文献
937.
938.
939.
940.
华北板块北缘中段含铁变质岩系的时代和构造环境初探 总被引:15,自引:1,他引:15
内蒙北部苏尼特右旗以北二道井、哈拉干和红格尔地区的含铁变质岩系中变质基性火山岩Sm-Nd全岩等时线年龄为1511±76Ma,这表明该岩系属中元古代而不是以往推测的早古生代,等时线的εNd(t)值为+6.3±1.7,属亏损型地幔源区岩相学分析表明它形成于规模不大,具中等水深和较弱水动力条件的较封闭海域。据上述特征推测,华北板块北缘中曾存在中元古代初动型火山陆缘。 相似文献