| 吉林二密铜矿区含矿次火山岩年代学及其形成环境探讨 |
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| 关键词:U-Pb content of zircons volcanic and sub-volcanic fluids Ermi |
| 基金项目:中国地质调查局地质调查项目(编号: 12120113090100);国土资源部公益性行业科研专项(编号: 201111002-01) |
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| A Discussion on the Chronology and Formation Environment of the Ore-bearing Sub-volcanic Rocks in the Ermi Copper Deposit, Jilin Province |
| The sub-volcanic rocks in the Ermi copper deposit constitute the host rocks of the copper orebodies. As their ages remain unclear, many basic geological problems, such as the mechanism of their intrusion and the mineralization of the deposit, remain controversial. In this paper, the technique of LA-MC-ICP-MS was applied to determining the age of the sub-volcanic rocks. The results show that the weighted 206Pb/238U ages of the zircons from monzodiorite porphyrite (JEM02), monzodiorite (JEM03-1) and quartz monzonite (JEM03-2), are (95.71±0.33) Ma (MSWD=1.6), (97.18±0.46) Ma (MSWD=1.19), and (96.10±0.50) Ma (MSWD=2.0), respectively, which are consistent with their corresponding concordant ages, and therefore the intrusion sequence of the sub-volcanics should be quartz monzodiorite, quartz monzonite, and monzodiorite porphyrite. According to the investigation of the composition of the sub-volcanics, the sub-volcanics should be island-arc granitoid-A type granitoid formed in the environment from the post-collision to late-orogenic or anorogenic stage. Combined with the ages of these sub-volcanics, the formation process of the sub-volcanics are considered to be as follows: the lithospheric thinning of eastern China triggered the interaction between the enriched mantle and the crust, and formed the calc-alkaline magma with alkali enrichment. The calc-alkaline magma evolved into two types of magma (monzodiorite-quartz monzonite magma and monzodiorite porphyrite-granite porphyry magma) in the magma chamber in the course of the magma rising, and formed the two kinds of sub-volcanics. |
| XING Shu-wen,ZHANG Zeng-jie,MA Yu-bo,DU Xiao-hui,SUN Jing-gui,ZHANG Yong,YANG Feng-chao,WANG Yan.2014.A Discussion on the Chronology and Formation Environment of the Ore-bearing Sub-volcanic Rocks in the Ermi Copper Deposit, Jilin Province[J].Acta Geoscientica Sinica,35(5):619-626. |
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