论文部分内容阅读
印度西北部拉贾斯坦邦拉杰普拉-达里巴带位于达里巴和辛德斯瓦尔卡拉(SindesWar Kalan)的中元古变质层状沉积容矿岩Zn-pb-Cu硫化物矿床中的86个硫化物矿物的硫同位素组成已经测定,另外该矿带还有16个含碳的和12个碳酸盐岩石样品,对它们的总碳和有机碳含量以及碳同位素组成作了分析。硫同位素组成从9.1‰到6.7‰(中间值1.9‰),向上地层的δ~(34)S值增大,特别明显的是黄铁矿和磁黄铁矿其中的硫认为是同生成因的。在条带状矿石样品中的连续薄层,矿物中没有明显的横向同位素变化或同位素变化出现。根据共存硫化物之间硫同位素的分离,认为矿床在经受角闪岩相变质作用时基本上保存了原始同位素模式,在含碳岩石中有机碳含量范围在0.5—9.3Wt％,δ~(13)C值在-21‰-31‰(平均值-25.‰)之间,保持碳的生物成因来源。重结晶白云岩中其δ~(13)C值接近-14.4‰。与下列成因图式相一致的地质证据和同位素特征有:(a)贱金属矿石沿着携带H_2S的热液喷气形成的带,受海水硫酸盐化学还原和镁铁质火山岩淋滤在生物高度活动的半封闭(含SO_4)浅水和裂谷盆地中形成,(b)黄铁矿和磁黄铁矿是在H_2S开放系统的孔隙海水中因硫酸盐受细菌还原成岩形成,因此在地层向上部位的这些矿物中~(34)S逐渐发生富集,(c)该带向北,在辛德斯瓦卡拉矿石沉积盆地相对更为开阔。
Rajapra-Daribar zone, Rajasthan, northwestern India, is located in the Zn-pb-Cu sulphide deposit of the Proterozoic metamorphic bedded sedimentary ore deposits in Dar es Salaam and SindesWar Kalan The sulfur isotopic composition of 86 sulfide minerals has been determined. In addition, there are 16 samples of carbon and 12 carbonate rocks in this belt. Their total carbon and organic carbon contents and their carbon isotopic compositions are also analyzed. The sulfur isotope composition ranges from 9.1 ‰ to 6.7 ‰ (median 1.9 ‰), and the δ ~ (34) S value of the upward strata increases. It is especially obvious that the sulfur in pyrite and pyrrhotite is considered as an anomaly . In a continuous thin layer of banded ore samples, there is no significant lateral isotope change or isotopic change in minerals. According to the separation of sulfur isotopes between the coexisting sulfides, it is considered that the ore deposit basically preserved the original isotopic pattern under the amphibolite facies metamorphism. The contents of organic carbon in the carbonaceous rocks range from 0.5 to 9.3 wt% and δ to 13 ) The C value is between -21 ‰ and -31 ‰ (average -25. ‰), keeping the biogenic origin of carbon. The δ ~ (13) C value of recrystallized dolomite is close to -14.4 ‰. Geological evidence and isotopic characteristics consistent with the following genetic patterns are: (a) bands formed by base metal ores along H_2S-bearing hydrothermal jets that are subjected to seawater sulphate chemical reduction and mafic volcanic leaching during bio-altitude activities (SO_4) shallow water and rift basins. (B) Pyrite and pyrrhotite are formed by bacterial reduction of diagenesis into pore water of H_2S open system. Therefore, in the upper part of the strata The ~ (34) S of these minerals is gradually enriched, (c) the belt is northward and relatively more open in the Sindhsvarkara ore depositional basin.