| 冈底斯西段首例银锡多金属矿床的发现、成因及意义 |
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| 引用本文： | 高顺宝,郑有业,姜晓佳,李伟良,姜军胜.冈底斯西段首例银锡多金属矿床的发现、成因及意义[J].地球科学,2020,45(12):4463-4480. |
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| 作者姓名： | 高顺宝 郑有业 姜晓佳 李伟良 姜军胜 |
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| 作者单位： | 1.中国地质大学地质调查研究院, 湖北武汉 430074 |
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| 基金项目： | 国家地质调查项目DD20190159-33国家重点研发计划项目2016YFC0600300 |
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| 摘 要： | 最新的矿产调查工作在冈底斯西段火山岩区新发现了拔隆银锡多金属矿床，地表矿体表现为受火山沉积断陷盆地边缘逆冲断隆带、火山机构及次级断裂控制的脉状矿体.为了查明该矿床的成因，开展了含矿火山岩锆石U-Pb年代学、矿石矿物学、地球化学及S-Pb同位素等研究.结果表明:拔隆矿床含矿火山岩锆石LA-ICP-MS U-Pb加权平均年龄为126.5±1.2 Ma，矿物组合以中低温为主、兼有少量中高温矿物，闪锌矿Zn/Cd和Zn/Fe比值变化分别介于321~17 407、2.4~4.4，黄铁矿Co/Ni比值为2.2~3.6，硫化物样品δ34S值变化于2.94‰~4.48‰，206Pb/204Pb比值为18.590~18.779，207Pb/204Pb比值为15.636~15.865，208Pb/204Pb比值为38.883~39.991，具有岩浆硫、上地壳铅特征，矿床的形成与冈底斯西段早白垩世火山活动晚期的次火山热液密切相关.经与世界典型银锡多金属矿床的对比认为，拔隆矿床的成矿特征与世界大型-超大型银锡多金属矿床较相似，地表矿体属于浅成低温热液型银多金属矿体，向下可能发育有斑岩型锡多金属矿体.拔隆矿床富银含锡的成矿特征在冈底斯西段属于首次发现，该发现不仅为研究冈底斯西段火山岩区矿床成因类型提供了新的资料和约束，还极大地拓宽了冈底斯西段火山岩区的找矿视野.
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| 关 键 词： | 银锡多金属 陆相火山活动 斑岩-浅成低温热液型 冈底斯西段 矿床 |
| 收稿时间： | 2020-07-08 |
Discovery,Genesis and Significances of First Siver-Tin Polymetal Deposit in Western Gangdese Belt |
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| Abstract: | The Balong Ag-Sn polymetallic deposit was newly discovered in the volcanic rock area of western Gangdese by mineral resources investigation project. The surface ore bodies are vein type ore bodies controlled by the coupling of thrust belt, volcanic mechanism and secondary faults in the margin of volcano-sediment graben basins. In order to find out the genesis of Balong deposit, the zircon U-Pb geochronology, ore mineralogy, mineral geochemistry and S-Pb isotopes were carried out. The results show that the weighted average age of zircon LA-ICP-MS U-Pb is 126.5±1.2 Ma in the ore-bearing volcanic rocks, the mineral assemblage is mainly composed of medium-low temperature minerals and a small amount of medium-high temperature minerals, the Zn/Cd and Zn/Fe ratios of sphalerite are 321-17 407 and 2.4-4.4, the Co/Ni ratio of pyrite is 2.2-3.6, the δ 34S value of sulfide changes from 2.94 ‰ to 4.48 ‰, the 206Pb/204Pb ratio is 18.590-18.779, the 207Pb/204Pb ratio is 15.636-15.865, the 208Pb/204Pb ratio is 38.883-39.991.The above results show that the formation of the deposit is closely related to the subvolcanic hydrothermal fluid of the late stage of Early Cretaceous volcanic activity in the western Gangdese, and the ore-forming materials have the characteristics of magmatic sulfur and lead in the upper crust. Compared with the typical Ag-Sn polymetallic deposits in the world, the metallogenic characteristics of the Balong deposit are similar to those of the world's large-superlarge scale Ag-Sn polymetallic deposits. The surface ore body belongs to the epithermal silver-polymetallic orebody, and the porphyry tin-polymetallic orebody may develop downward. The metallogenic characteristics of Ag-rich and Sn-bearing deposit in the western Gangdese are firstly discovered. This discovery not only provides new data and constraints for the study of the genetic types of the deposits in the volcanic rock area of the western Gangdese, but also greatly broadens the prospecting horizon in the area. |
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