西昆仑奇台达坂一带晚三叠世中酸性侵入岩锆石LA-ICP-MS年龄、地球化学特征及其构造意义
发布时间：2018-07-28 12:55
【摘要】：奇台达坂位于新疆西昆仑新藏公路540km处,在其周围分布有小规模的中酸性侵入岩,岩体严格受郭扎错—金沙江缝合带控制呈北西向展布,岩性主要为英云闪长岩、石英闪长岩和花岗闪长岩。锆石环带结构明显,Th/U值介于0.15~0.73之间,为典型的岩浆锆石。LA-ICP-MS锆石U-Pb同位素测年结果表明,其形成年龄分别为214.7±2.0 Ma、211.3±3.3 Ma和210.6±2.8 Ma,时代为晚三叠世。主微量元素英云闪长岩→石英闪长岩→花岗闪长岩,岩石中SiO_2(58.96%~67.52%)含量逐渐增高,Al_2O_3(14.79%~16.37%)、CaO(3.41%~5.25%)和Mg O(1.47%~3.42%)逐渐降低;里特曼指数1.03~1.79,K_2O+Na_2O全碱含量为4.36%~6.4%,属钙碱性系列。稀土元素中等(∑REE=101.27×10-6~271.04×10-6),轻重稀土分异明显(LaN/YbN平均为10.69),Eu异常明显(δEu平均值0.60)。大离子亲石元素(LILE)Rb、K、Th富集、相对亏损Ba,高场强元素(HFSE)Nb、Zr、Hf、Sr、P、Ti亏损。对研究区侵入岩进行投图分析,认为它是形成于大陆边缘弧环境的未分异I型花岗岩,物质来源主要为岩浆弧地壳的角闪岩相变玄武岩,并卷入少量的地幔物质。根据岩体的成因类型并结合区域构造环境演化认为,在晚三叠世末,古特提斯洋南缘局限洋盆(巴颜喀拉中生代边缘裂陷海洋盆)发生自NE向SW的持续俯冲消减,洋—陆转换开始,该套中酸性侵入岩侵入就位。
[Abstract]:Qitaidaban is located at the 540km of Xin-Tibet Highway in West Kunlun, Xinjiang, and has a small scale of intermediate-acid intrusive rocks around it. The rock mass is strictly controlled by the Guozhai-Jinshajiang suture zone and distributes in the north-west direction, and the lithology is mainly composed of quartz diorite. Quartz diorite and granodiorite. The U-Pb isotopic dating of zircon 路LA-ICP-MS shows that the age of zircon formation is 214.7 卤2.0 Ma 211.3 卤3.3 Ma and 210.6 卤2.8 Ma, respectively, and the age is late Triassic. The content of SiO_2 (58.96%, 67.52%) in the main trace element Yingyun diorite and quartz diorite is gradually increasing. The content of Al2O3 (14.7920%) Cao (3.41%) and Mg O (1.470.42%) decreases gradually, and the whole alkali content of the Richman index 1.031.79 K2O Na_2O is 4.366.40.It belongs to the calc-alkaline series. The rare earth elements are moderate (鈭，
本文编号：2150212
[Abstract]:Qitaidaban is located at the 540km of Xin-Tibet Highway in West Kunlun, Xinjiang, and has a small scale of intermediate-acid intrusive rocks around it. The rock mass is strictly controlled by the Guozhai-Jinshajiang suture zone and distributes in the north-west direction, and the lithology is mainly composed of quartz diorite. Quartz diorite and granodiorite. The U-Pb isotopic dating of zircon 路LA-ICP-MS shows that the age of zircon formation is 214.7 卤2.0 Ma 211.3 卤3.3 Ma and 210.6 卤2.8 Ma, respectively, and the age is late Triassic. The content of SiO_2 (58.96%, 67.52%) in the main trace element Yingyun diorite and quartz diorite is gradually increasing. The content of Al2O3 (14.7920%) Cao (3.41%) and Mg O (1.470.42%) decreases gradually, and the whole alkali content of the Richman index 1.031.79 K2O Na_2O is 4.366.40.It belongs to the calc-alkaline series. The rare earth elements are moderate (鈭，
本文编号：2150212
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