| 东昆仑巴隆地区晚三叠世石英闪长岩成因:U?Pb年代学、地球化学及Sr?Nd?Hf同位素制约 |
| |
| 引用本文： | 黄啸坤,魏俊浩,李欢,陈梦婷,王艺龙,李国猛,闫茂强,张新铭.东昆仑巴隆地区晚三叠世石英闪长岩成因:U?Pb年代学、地球化学及Sr?Nd?Hf同位素制约[J].地球科学,2021,46(6):2037-2056. |
| |
| 作者姓名： | 黄啸坤 魏俊浩 李欢 陈梦婷 王艺龙 李国猛 闫茂强 张新铭 |
| |
| 作者单位： | 中国地质大学资源学院,湖北武汉 430074;辽宁省地质勘查院有限责任公司,辽宁大连 116100;高分辨率对地观测系统辽宁地质资源环境应用与服务中心,辽宁大连 116100 |
| |
| 基金项目： | 国家自然科学基金项目41772071 |
| |
| 摘 要： | 花岗岩的研究对于反演造山带下地壳物质组成、造山作用深部动力学过程具有重要意义.对位于东昆仑造山带东段的巴隆石英闪长岩开展了锆石U-Pb年代学、Hf同位素地球化学、全岩主微量元素地球化学和Sr-Nd同位素地球化学研究，以探讨其岩石成因和构造背景.岩体LA-ICP-MS锆石U-Pb定年结果为229.5±1.4 Ma，为晚三叠世岩浆活动产物.全岩SiO2含量为59.86%~61.83%，显示高Na2O（3.38%~3.55%）和Al2O3（16.38%~17.03%）特征，Na2O/K2O为1.25~1.39，Mg#为50.1~52.3，属高钾钙碱性系列.稀土元素标准化图呈右倾，具有较弱的负铕异常（δEu=0.71~0.82），微量元素蛛网图显示富集大离子亲石元素（LILE），显著亏损高场强元素（HFSE）.石英闪长岩的高Sr（474~609×10-6）、Sr/Y（32.31~40.86）、（La/Yb）N（13.34~15.32）和低Yb（1.34~1.75×10-6）、Y（13.40~15.60×10-6）含量与埃达克质岩石特征相似.全岩（87Sr/86Sr）i为0.708 186~0.708 428，εNd（t）为-5.75~-5.27，对应的二阶段模式年龄tDM2（Nd）为1 432~1 471 Ma；εHf（t）为-5.2~-3.2，tDM2（Hf）为1 305~1 420 Ma.岩相学、元素地球化学和Sr-Nd-Hf同位素结果揭示石英闪长岩起源于加厚下地壳的部分熔融，并混有幔源岩浆.构造判别图解显示巴隆石英闪长岩体形成于后碰撞伸展构造环境.东昆仑与巴颜喀拉地体的陆陆碰撞导致板片断离，软流圈物质上涌，使富集地幔熔融并底侵下地壳，下地壳部分熔融形成巴隆石英闪长岩.
|
| 关 键 词： | 石英闪长岩 晚三叠世 壳幔混合作用 后碰撞 东昆仑造山带 岩石学 地球化学 |
| 收稿时间： | 2020-04-27 |
Zircon U-Pb Geochronological,Elemental and Sr-Nd-Hf Isotopic Constraints on Petrogenesis of Late Triassic Quartz Diorite in Balong Region,East Kunlun Orogen |
| |
| Huang Xiaokun,Wei Junhao,Li Huan,Chen Mengting,Wang Yilong,Li Guomeng,Yan Maoqiang,Zhang Xinming.Zircon U-Pb Geochronological,Elemental and Sr-Nd-Hf Isotopic Constraints on Petrogenesis of Late Triassic Quartz Diorite in Balong Region,East Kunlun Orogen[J].Earth Science-Journal of China University of Geosciences,2021,46(6):2037-2056. |
| |
| Authors: | Huang Xiaokun Wei Junhao Li Huan Chen Mengting Wang Yilong Li Guomeng Yan Maoqiang Zhang Xinming |
| |
| Abstract: | The study of granite is of great significance to the inversion of the material composition of the lower crust and the deep dynamic process of orogeny. The quartz diorite in Balong region is located in the east of the East Kunlun orogen. In this paper, it presents LA-ICP-MS zircon U-Pb age for the Balong quartz diorite to determine precisely the time of the magmatism, and also presents geochemical, Sr-Nd-Hf isotope data for the Balong quartz diorite to constrain the petrogenesis and tectonic setting. The LA-ICP-MS U-Pb analyses of zircon yielded a weighted mean age of 229.5±1.4 Ma, indicating that it was emplaced in the Late Triassic. The quartz diorites have contents of SiO2 (59.86%-61.83%), Na2O (3.38%-3.55%), Al2O3 (16.38%-17.03%) with Na2O/K2O ratios ranging from 1.25 to 1.39 and Mg# values ranging from 50.1 to 51.2. They are characterized by high silicon and belonging to the high-potassium-calcium-alkaline rock. Meanwhile, they are enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements(HFSEs). In addition, the quartz diorite shows characteristics of high Sr/Y (32.31-40.86) and (La/Yb)N (13.34-15.32) and low contents of Yb (1.34×10-6-1.75×10-6) and Y (13.40×10-6-15.60×10-6). These features indicate that the quartz diorite is similar to adakite. All rock samples are enriched in large ion lithophile elements and light rare earth elements, but depleted in high field strength elements. The (87Sr/86Sr)i ratios range from 0.708 186 to 0.708 428, εNd(t) values range from -5.75 to -5.27 with corresponding two-stage Nd model ages ranging from 1 432 to 1 471 Ma. The εHf(t) values are from -5.2 to -3.2 and two-stage Hf model ages rang from 1 305 to 1 420 Ma. Integrated geological, geochemical and isotopic data suggest that the quartz diorite from Balong region is most likely generated via partial melting of thickened mafic lower continental crust and with subordinate mantle-derived basic magma. In combination with the tectonic evolution of the East Kunlun orogenic belt and the geochronological and geochemical characteristics of contemporary intrusive rocks, it is concluded that the quartz diorite from Balong region was formed in post-collisional extensional tectonic environment. Slab break-off, triggered by continuous collision between the Bayanhar block and EKOB, led to underplating of basic magma formed by partial melting of enriched mantle. The quartz diorite from Balong region was formed by partial melting of lower crust. |
| |
| Keywords: | |
| 本文献已被 CNKI 万方数据 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
