| 东昆仑与成矿有关的三叠纪花岗岩演化:基于莫河下拉岩体岩石学、地球化学和锆石U-Pb年代学的证据 |
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| 引用本文： | 张炜,周汉文,朱云海,毛武林,佟鑫,马占青,曹永亮.东昆仑与成矿有关的三叠纪花岗岩演化:基于莫河下拉岩体岩石学、地球化学和锆石U-Pb年代学的证据[J].地球科学,2016,41(8):1334-1348. |
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| 作者姓名： | 张炜 周汉文 朱云海 毛武林 佟鑫 马占青 曹永亮 |
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| 作者单位： | 1.中国地质大学地球科学学院，湖北武汉 430074 |
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| 基金项目： | 中国地质调查局地质调查工作项目1212011086001 |
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| 摘 要： | 东昆仑造山带在三叠纪不仅是一个重要的构造-岩浆带，也是一个对于国民经济非常重要的多金属成矿带.该区在三叠纪形成了大量与成矿有关的花岗岩，它们之间的联系、与区域构造运动的关系目前尚未明确.在莫河下拉银多金属矿花岗斑岩岩相学、地球化学和锆石年代学的研究基础上，总结了东昆仑地区三叠纪与成矿有关花岗岩的基本特征，并探讨了它们的演化规律.结果表明:(1) 东昆仑与成矿有关的三叠纪花岗岩年龄为250~200 Ma，具有一个由低K系列-中K钙碱性系列向高K系列-钾玄岩系列过渡的明显趋势，240~200 Ma，A/NK比值由2.00降到1.00；(2)(87Sr/86Sr)i为0.710~0.715，εNd(t)值为-0.6~0.0，εHf(t)主要集中在-5~1，峰值为-2~-1，表明东昆仑与成矿有关三叠纪花岗岩物质主要来源于古老的地壳物质，同时有少量的幔源物质加入；(3) 东昆仑地区在240 Ma进入后造山阶段，出现大规模的钙碱性花岗岩，220 Ma之后花岗岩大量减少，210~204 Ma出现的花岗岩以碱性A型花岗岩为主，标志着碰撞造山结束进入到板内裂解阶段.
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| 关 键 词： | 三叠纪花岗岩 地球化学 岩石学 后碰撞 莫河下拉 东昆仑造山带 |
| 收稿时间： | 2016-03-08 |
The Evolution of Triassic Granites Associated with Mineralization within East Kunlun Orogenic Belt: Evidence from the Petrology,Geochemistry and Zircon U-Pb Geochronology of the Mohexiala Pluton |
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| Abstract: | The East Kunlun orogenic belt is not only an important intrusive magmatic tectonic belt, but also a very important poly-metallic metallogenic belt for national economy. There are a large number of granites associated with mineralization formed in Triassic in this area, but the connection between them and the relationship about the tectogenesis are still not clear. In this paper, detailed petrography, element geochemical and zircon geochronological studies are presented for the Mohexiala granite-porphyry associated with silver poly-metallic ore; we summarize the characteristics of Triassic granites associated with mineralization within the East Kunlun orogenic belt, and discuss their evolution. Results show that: (1) the Triassic granites associated with mineralization within East Kunlun orogenic belt have a clear trend from low-K and mid-K calc-alkaline series to high-K calc-alkaline and shoshonite series during 250-200 Ma, their A/NK ratios decreased from 2.0 to 1.0 during 240-200 Ma; (2) the (87Sr/86Sr)i ratios between 0.710 to 0.715, εNd(t)=-0.6-0.0, the value of εHf(t) are concentrated in -5-1 and the peak ranges between -2 to -1, indicating that the East Kunlun Triassic granites associated with mineralization were derived from the sources of ancient crust and mixed by mantle material; (3) the East Kunlun area got into the post-orogenic stage at 240 Ma and a large number of calc-alkaline granites formed, the granites gradually reduced after 220 Ma and some alkaline A-type granites occurred between 204 Ma and 210 Ma which indicates that the orogenic belt transformed from collision-orogeny to the intraplate break-up stage. |
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