| 西藏角东黑云二长花岗斑岩中绿泥石矿物学特征及其地质意义 |
| 投稿时间：2024-09-24 修订日期：2024-11-20 点此下载全文 |
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| 基金项目:国家重点研发计划青年科学家项目（2021YFC2900100）、中国地质科学院矿产资源研究所基本科研业务费（KK2306）中国地质调查局地质调查项目（DD20230360、DD20243483） |
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| 中文摘要:角东钨-铌钽矿区是近年来新发现的与淡色花岗岩-伟晶岩有关的稀有金属矿区。通过野外地质调查,作者于该矿区发现一处黑云二长花岗斑岩岩体,并伴有强烈硅化、绿泥石化和孔雀石化发育。基于详尽的岩相学研究,对角东矿区黑云二长花岗斑岩中绿泥石进行了电子探针组分分析,限定了其形成的物理化学条件,并研判了斑岩成矿潜力。黑云二长花岗斑岩中绿泥石为典型铁镁绿泥石,其形成温度为177~211℃,属黑云母受中-低温流体蚀变所形成。绿泥石的AlIV为1.01~1.30,Fe2+/(Fe2++Mg2+)值介于0.64~0.77之间,Cr/Ti值为0.02~27.13,氧逸度为-38.6~-34.0,硫逸度为-13.3~-10.8。相较于西藏典型斑岩型矿床青磐岩化带中绿泥石,角东黑云二长花岗斑岩中绿泥石以其较高的AlIV、Fe2+/(Fe2++Mg2+)、硫逸度,中等的温度、Cr/Ti值、氧逸度,表现出具有一定斑岩铜矿的成矿潜力。 |
| 中文关键词:绿泥石 黑云二长花岗斑岩 斑岩成矿潜力 角东 |
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| Mineralogical characteristics and geological significance of chlorite in biotite monzogranite porphyry from the Jiaodong mineralization area, Xizang |
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| Abstract:The Jiao Dong W-Nb-Ta ore district is a newly discovered rare metal deposit associated with leucogranite-pegmatite systems. Through field geological surveys, the authors identified a biotite monzogranite porphyry intrusion in this district, characterized by intense silicification, chloritization, and malachitization. Based on detailed petrographic studies, electron probe microanalysis (EPMA) was conducted on chlorite within the biotite monzogranite porphyry from the Jiao Dong district to constrain its physicochemical formation conditions and assess the porphyry mineralization potential. The chlorite in the biotite monzogranite porphyry is identified as typical Fe-Mg chlorite, formed at temperatures ranging from 177 to 211°C, indicative of biotite alteration by medium- to low-temperature fluids. The chlorite exhibits AlIV values ranging from 1.01 to 1.30, Fe2+/(Fe2++Mg2+) ratios between 0.64 and 0.77, Cr/Ti ratios from 0.02 to 27.13, oxygen fugacity (fO2) values from -38.6 to -34.0, and sulfur fugacity (fS2) values from -13.3 to -10.8. Compared to chlorite from the propylitic alteration zones of typical porphyry deposits in Tibet, the chlorite in the biotite monzogranite porphyry from the Jiao Dong district is characterized by higher AlIV, Fe2+/(Fe2++Mg2+), and sulfur fugacity, as well as moderate temperature, Cr/Ti ratios, and oxygen fugacity. These characteristics suggest a certain potential for porphyry copper mineralization. |
| keywords:Chlorite Biotite monzogranite porphyry Porphyry metallogenic potential Jiaodong |
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