| 冈底斯中段岗讲斑岩铜钼矿床锆石U-Pb和辉钼矿Re-Os年代学及其地质意义 |
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| 引用本文： | 杨震,姜华,杨明国,梅红波,胡光道,张黎黎,张裴培.冈底斯中段岗讲斑岩铜钼矿床锆石U-Pb和辉钼矿Re-Os年代学及其地质意义[J].地球科学,2017,42(3):339-356. |
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| 作者姓名： | 杨震 姜华 杨明国 梅红波 胡光道 张黎黎 张裴培 |
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| 作者单位： | 1.中国地质大学资源学院，湖北武汉 430074 |
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| 基金项目： | 云南铜业 (集团) 有限公司和中国地质大学 (武汉) 合作项目2010026410 |
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| 摘 要： | 岗讲铜钼矿床是西藏冈底斯成矿带中段典型的斑岩型矿床，岗讲矿床成岩成矿时代、岩浆演化过程及其与成岩成矿关系尚不明确，利用LA-ICP-MS锆石U-Pb定年方法对岗讲矿区主要岩体二长花岗斑岩、花岗闪长斑岩和英云闪长玢岩成岩时代进行研究，获得锆石U-Pb年龄加权平均值分别为16.6±0.3 Ma (MSWD=0.94，n=10)、16.1±0.2 Ma (MSWD=1.07，n=12)、14.4±0.4 Ma (MSWD=1.12，n=7)；同时采用辉钼矿Re-Os同位素测年方法首次对岗讲矿床石英硫化物脉中的辉钼矿进行定年，获得12件辉钼矿Re-Os同位素模式年龄集中于13.24±0.20 Ma~13.55±0.22 Ma，加权平均年龄为13.4±0.1 Ma (MSWD=0.65)，等时线年龄为13.6±1.6 Ma (MSWD=1.2).结果表明:(1) 岗讲矿区复式岩体侵入序列为含巨斑黑云二长花岗岩-二长花岗斑岩-花岗闪长斑岩-流纹斑岩 (深部定名为英云闪长玢岩)，成岩时限为16.6~14.4 Ma，成矿时代为13.4 Ma左右，成岩成矿是一个连续的岩浆演化过程；(2) 辉钼矿中Re含量为155.4~171.1 μg/g，均值为162.9 μg/g，指示其成矿物质中有幔源成分的加入；(3) 矿床产出于中新世印度-亚洲大陆碰撞后伸展构造环境.
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| 关 键 词： | 地球化学 锆石U-Pb测年 辉钼矿Re-Os测年 斑岩铜钼矿床 冈底斯 |
| 收稿时间： | 2016-10-01 |
Zircon U-Pb and Molybdenite Re-Os Dating of the Gangjiang Porphyry Cu-Mo Deposit in Central Gangdese and Its Geological Significance |
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| Abstract: | The Gangjiang Copper-Molybdenum deposit is a typical porphyry deposit, which locates in the Central Gangdese metallogenic belt. In order to determine the ages of magmatism and mineralization, and disentangle the complicated magmatic evolution and the relationship between magmatic process and copper-molybdenum mineralization, the author carried out a study of LA-ICP-MS zircon U-Pb ages of the monzogranite porphyry, granodiorite porphyry, and tonalite porphyrite in Gangjiang mining area. It is shown that the zircon U-Pb weighted isochron ages are 16.6±0.3 Ma (MSWD=0.94, n=10), 16.1±0.2 Ma (MSWD=1.07, n=12), 14.4±0.4 Ma (MSWD=1.12, n=7). Meanwhile, twelve molybdenite samples separated from quartz sulfides in Gangjiang copper orebodies were used for Re-Os dating, and the model ages obtained range from 13.24±0.20 Ma to 13.55±0.22 Ma, with weighted average 13.4±0.1 Ma (MSWD=0.65) and isochron age 13.6±1.6 Ma (MSWD=1.2). On the basis of geological studies, and conbined with the results mentioned above and previous research data, it is proposed that the rock mass intrusion sequence is monzogranite porphyry→granodiorite porphyry→tonalite porphyrite→rhyolite porphyry. The porphyry occurred ranges from 16.6 Ma to 14.4 Ma, and the mineralization age of Gangjiang deposit is about 13.4 Ma, and petrogenetic and metallogenic is a continuous process of magmatic evolution. The Re content of the molybdenite is 155.4-171.1 μg/g, with an average of 162.9 μg/g, suggesting that the metallogenic material originated from a source with mantle components. Gangjiang porphyry copper-molybdenum deposit was formed in post-collisional extension setting of India-Asia continental collision orogenic belt during the Miocene. |
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