| 滇西双江县勐库地区临沧花岗岩中暗色包体锆石U-Pb年代学及其地质意义 |
| |
| 引用本文： | 曾文涛,孙载波,周坤,吴嘉林,黄亮,赵江泰.滇西双江县勐库地区临沧花岗岩中暗色包体锆石U-Pb年代学及其地质意义[J].沉积与特提斯地质,2018,38(1):23-36. |
| |
| 作者姓名： | 曾文涛 孙载波 周坤 吴嘉林 黄亮 赵江泰 |
| |
| 作者单位： | 云南省地质环境监测院;云南省地质调查院;国土资源部三江成矿作用及资源勘查利用重点实验室 |
| |
| 基金项目： | 中国地质调查局地质调查项目(121201010000150007)和云南省科技领军人才培养计划项目(2013HA001) |
| |
| 摘 要： | 位于三江南段双江勐库地区的临沧花岗岩,主体岩性为黑云母二长花岗岩,其次为黑云母花岗闪长岩和碱长花岗岩。通过野外地质调查,在勐库热水塘附近黑云二长花岗岩中发现了与其紧密共生的暗色镁铁质微粒包体(MME)—闪长岩。本文对暗色闪长岩包体进行了岩相学观察、LA-ICP-MS锆石U-Pb定年和全岩主量元素分析。暗色闪长岩包体LA-ICP-MS锆石U-Pb年龄为230.9±1.2Ma,与中细粒黑云二长花岗岩LA-ICP-MS锆石U-Pb年龄(229.2±0.8Ma)基本一致。岩石地球化学特征表明,黑云二长花岗岩富K2O和Na2O,Na2OK2O,富Al2O3,铝饱和指数A/CNK平均为1.17;闪长岩K2O和Na2O含量中等,Na2OK2O,富Al2O3和Mg O,铝饱和指数A/CNK平均为0.77。二者稀土配分曲线为右倾的轻稀土富集型,二者均富集大离子亲石元素而亏损高场强元素Nb、Ta等,均具有相对较高的Mg#(黑云二长花岗岩30.50~61.41;闪长岩58.58~67.34)。中细粒黑云二长花岗岩Cr、Ni含量(平均值分别为46.96×10-6和11.21×10-6)小于闪长岩Cr、Ni含量(平均值分别为197.62×10-6和75.68×10-6)。综合研究表明,该地区花岗质岩浆的形成很可能与地幔流体作用引发的地壳部分熔融与壳幔岩浆混合作用密切相关,形成于陆陆碰撞-后碰撞的构造背景,暗示保山地块与思茅地块在230Ma已经进入了陆陆碰撞-后碰撞的地质时期。
|
| 关 键 词： | 锆石U-Pb年代学 岩石地球化学特征 暗色包体 临沧花岗岩 滇西双江县勐库 |
| 收稿时间： | 2017/5/15 0:00:00 |
| 修稿时间： | 2017/7/10 0:00:00 |
U-Pb dating of the detrital zircons in the dark diorite enclaves from the Lincang granites in Mengku, Shuangjiang, western Yunnan and its geological significance |
| |
| ZENG Wen-tao,SUN Zai-bo,ZHOU Kun,WU Jia-lin,HUANG Liang,ZHAO Jiang-tai.U-Pb dating of the detrital zircons in the dark diorite enclaves from the Lincang granites in Mengku, Shuangjiang, western Yunnan and its geological significance[J].Sedimentary Geology and Tethyan Geology,2018,38(1):23-36. |
| |
| Authors: | ZENG Wen-tao SUN Zai-bo ZHOU Kun WU Jia-lin HUANG Liang ZHAO Jiang-tai |
| |
| Institution: | 1. Yunnan Institute of Environmental Monitoring, Kunming 650216, Yunnan, China;2. Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China;3. Key Laboratory of Sangjiang Metallogeny and Resources Exploration and Utilization, Ministry of Land and Resources, Kunming 650016, Yunnan, China |
| |
| Abstract: | The Lincang granites in Mengku, Shuangjiang, western Yunnan consist, lithologically, of biotite monzogranite, biotite granodiorite and alkali feldspar granite. The dark mafic microgranular diorite enclaves (MME) were discovered in biotite monzogranite near Reshuitang, Mengku during our field geological survey. The present paper focuses on petrographic observation, LA-ICP-MS zircon U-Pb dating and whole-rock major elemental analysis of the dark diorite enclaves. The LA-ICP-MS zircon U-Pb age of 230.9 ±1.2 Ma for the dark diorite enclaves is roughly consistent with that of 229.2 ±0.8 Ma for the medium-to fine-grained biotite monzogranite. Geochemically, the biotite monzogranite is characterized by the enrichment of K2O and Na2O contents (Na2O > K2O) and Al2O3, and an average A/CNK ratio of 1.17, while the dark diorite has moderate contents of K2O and Na2O (Na2O > K2O), enrichment of Al2O3 and MgO, and an average A/CNK ratio of 0.77. Both the biotite monzogranite and dark diorite display the right-leaning LREE distribution patterns. They are all enriched in large ion lithophile elements (LILE) and depleted in the high field strength elements (HFSE) Na and Ta, and show relatively higher Mg# values (30.50 to 61.41 for biotite monzogranite and 58.58 to 67.34 for dark diorite, respectively). The Cr and Ni contents in biotite monzogranite range in 46.96×10-6 and 11.21×10-6, respectively, which are lower than those in dark diorite (an average ranging in 197.62×10-6 and 75.68×10-6, respectively). The formation of the granitic magmas in the study area may well be closely related with the partial crustal melting caused by mantle fluid action and crust-mantle magmatic mixing in the continental-continental collision to post-collisional tectonic settings, implying that the Baoshan and Simao blocks were in the continental-continental collision to post-collisional periods at the age of 230 Ma. |
| |
| Keywords: | zircon U-Pb dating geochemical signature dark enclaves Lincang granite Mengku in Shuangjiang western Yunnan |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《沉积与特提斯地质》浏览原始摘要信息 |
| 点击此处可从《沉积与特提斯地质》下载免费的PDF全文 |
|
