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湖北铜绿山矿床石英闪长岩的矿物学及Sr-Nd-Pb同位素特征 总被引：11，自引：8，他引：3
铜绿山是长江中下游鄂东南矿集区最重要的、大型夕卡岩型Cu-Fe(Au)矿床。本文对该矿区中与成矿密切的石英闪长岩进行了详细的矿物成分、地球化学及Sr-Nd-Pb同位素研究。结果表明:岩石中斜长石主要为更长石(An=21～31);角闪石贫Ti(0.2),高Mg/(Mg+Fe)(0.5),属于富镁角闪石;而黑云母为镁质黑云母。岩石的地球化学具有高硅(58.86%～67.71%),富碱(Na2O+K2O=5.67%～9.63%),富集轻稀土元素(LREE)和大离子亲石元素(LILE),并强亏损元素Nb、Ta、Ti等特征。岩石的(87Sr/86Sr)i为0.7055～0.7069,εNd(t)为-7.65～-3.44;(206Pb/204Pb)i=17.66～18.00,(207Pb/204Pb)i=15.49～15.56,(208Pb/204Pb)i=37.73～38.19。矿物成分、地球化学和同位素特征说明,铜绿山岩体与阳新岩体为同源岩浆的产物,源区为深度大于40km的富集地幔,经下地壳的混染及分离结晶作用形成。岩浆熔体形成的温度应大于889℃。角闪石和黑云母的温度计估算岩浆结晶温度分别为650～800℃和500～630℃,黑云母开始结晶温度略低于角闪石结晶结束温度,压力为1.49kbar,对应侵位深度约4.9km。岩浆具有利于Cu、Fe、Au等成矿元素进入熔体的条件,可能与板块俯冲作用相关。 相似文献
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S. K. Bhushan K. N. Rao K. T. Vidyadharan 《Journal of the Geological Society of India》2010,76(2):155-163
The present paper documents the petrography, mineral chemistry and petrochemistry of the acid volcanics of St.Mary group of
islands. These are essentially characterized by pyroxene bearing rhyolites with average 73.49 wt.% SiO2.All the rhyolites from these islands are acmite normative, hence peralkaline with phenocrysts of zoned plagioclase and sometimes
hypersthene/augite. There is depletion of LREE with moderate negative Eu anomaly. The enhancement of HFSE elements indicates
their compatibility with continental crust. These rhyolites have high equilibrium temperature (915°C) at relatively lower
oxygen fugacity (10−16). The acidic lava flows are anorogenic, within plate rhyolites, generated during northern migration of Indian plate over
Marion hotspot. 相似文献
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D. Purushothaman J. P. Mohakul Asit Saha K. T. Vidyadharan N. Rajendran 《Journal of the Geological Society of India》2009,73(6):744-746
Geochemical mapping has been carried out in Goa using soil/laterite and stream sediment as media. The geochemical maps for
U, Th, Nb and Ta show a conspicuous pattern in the NW part of Goa. The anomaly axis shows a NE-SW trend which is across the
formational trend. The nickel and copper distribution around Usgaon area, east of Ponda, have indicated anomalous signature
in the northern continuation of the Usgaon ultramafic complex. 相似文献
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T.H. Torsvik R.D. Tucker L.D. Ashwal L.M. Carter B. Jamtveit K.T. Vidyadharan & P. Venkataramana 《地学学报》2000,12(5):220-224
A U–Pb zircon age of 91.2 ± 0.2 Myr from western India (St. Mary islands) confidently links India with the Late Cretaceous magmatic province in Madagascar (≈ 84–92 Ma), and the U–Pb age is within analytical error of the U–Pb age of the Analalava gabbro pluton (91.6 ± 0.3 Myr) in northeastern Madagascar. Palaeomagnetic data from India and Madagascar allow us to postulate a new India–Madagascar fit (Euler latitude = 14.24°, longitude = 38.8° and rotation angle = –69.2°). This fit is applicable to the Late Cretaceous, directly prior to and during the early phase of Madagascar–India separation. In our Late Cretaceous reconstruction, south-west India runs roughly subparallel with the first known break-up related magnetic anomaly (A34); it maintains a close connection between Mada-gascar and India, but places India slightly rotated compared to the eastern margin of Madagascar and more northerly compared with some reconstructions. St. Mary magmatism is linked to the initial break-up between India and Madagascar, and magmatism probably resulted from rift-related extensional processes initially induced by the Marion hotspot underlying southern Madagascar during the Late Cretaceous. 相似文献
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白云鄂博地区碳酸岩墙及岩墙旁侧石英岩中的包裹体研究 总被引：11，自引：6，他引：11
白云鄂博的碳酸岩墙中包裹体类型有多子晶包裹体、两相水溶液包裹体、含CO_2三相包裹体和含子晶三相包裹体,岩相学和显微测温结果表明,这些包裹体与国外典型的碳酸岩中的包裹体具有很大程度的一致性,反映了其岩浆成因特点;碳酸岩墙中旁侧的白云鄂博H2石英岩中含有大量的流体包裹体,主要类型为NaCl-H_2O包裹体、CO_2包裹体和H_2O±CO_2±固体的包裹体。包裹体的岩相学、显微测温、阴极发光特征、包裹体成分ICP-MS测定,激光拉曼研究等,揭示出石英岩中的包裹体捕获了来自碳酸岩墙的碳酸岩浆流体,提供了一种不可多得的直接研究碳酸岩流体的手段。 相似文献
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