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| 藏北羌塘早古生代岩浆作用及其地质意义 |
| 解超明,李才,翟庆国,刘一鸣,王明,胡培远,范建军 |
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(1. 吉林大学地球科学学院, 吉林 长春 130061;
2. 吉林大学青藏高原地质研究中心, 吉林 长春 130061;
3. 自然资源部东北亚矿产资源评价重点实验室, 吉林 长春 130061;
4. 中国地质科学院地质研究所, 北京 100037;
5. 中国海洋大学海洋地球科学学院海底科学与探测技术教育部重点实验室, 山东 青岛 266100) |
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| 摘要: |
| 藏北羌塘早古生代岩浆作用及其构造演化对研究青藏高原早期演化历史以及羌塘盆地基底性质结构等具有重要科学意义。本文在综述前人研究基础上，系统总结了藏北羌塘地区早古生代岩浆岩的时空分布特征及年代学格架，初步探讨了青藏高原早古生代构造-岩浆事件对冈瓦纳大陆北缘构造演化以及羌塘盆地基底属性的约束。羌塘地区早古生代岩浆岩主要分布在日湾茶卡、都古尔、戈木日、本松错等地区，岩性以变质辉长岩、变质玄武岩、安山岩、花岗岩、变质流纹岩以及花岗片麻岩等为主。基于区域地质调查和年代学研究结果，羌塘地区早古生代发生了多期岩浆作用，分别为~500 Ma、~482 Ma、~474 Ma、~455 Ma、~438 Ma。这些岩浆岩可能是泛非造山运动结束后，冈瓦纳大陆北缘岩石圈伸展减薄的产物，并构成了羌南-保山板块早古生代的结晶基底，但有关伸展减薄的机制问题仍需开展进一步的研究工作，这些地质记录对恢复和反演青藏高原冈瓦纳大陆北缘的陆缘性质具有重要约束意义。 |
| 关键词: 青藏高原 早古生代 岩浆岩 羌塘基底 冈瓦纳 特提斯 |
| DOI：10.19826/j.cnki.1009-3850.2021.01004 |
| 附件 |
| 投稿时间：2020-12-30修订日期：2021-01-18 |
| 基金项目:国家自然科学基金项目（批准号：41872231，41972236）；自然资源部东北亚矿产资源评价重点实验室自主课题基金资助（编号：DBY-ZZ-18-06） |
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| The Early Paleozoic magmatism in Qiangtang, northern Tibet and its geological significance |
| XIE Chao-ming, LI Cai, ZHAI Qing-guo, LIU Yi-ming, WANG Ming, HU Pei-yuan, FAN Jian-jun |
(1. College of Earth Science, Jilin University, Changchun 130061, Jilin, China;
2. Research Center for Tibetan Plateau, Jilin University, Changchun 130061, Jilin, China;
3. Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Land and Resources of China, Changchun 130061, Jilin, China;
4. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;
5. Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Submarine Geosciences and Prospecting Techniques, Ministry of Education, College of Marine Geosciences, Ocean University of China, Qingdao 266100, China) |
| Abstract: |
| The Qiangtang early Paleozoic magmatism and its tectonic evolution are of great significance for the study of the early evolution of the Qinghai-Tibet Plateau and the basement properties and structures of the Qiangtang basin. This paper systematically summarizes the spatial and temporal distribution characteristics and chronological framework of the Early Paleozoic magmatic rocks in the Qiangtang region of northern Tibet, and preliminarily discusses the constraints of the Early Paleozoic tectonic-magmatic events and the tectonic evolution in the northern margin of Gondwana and the basement properties of the Qiangtang Basin on the Qinghai-Tibet Plateau. The results show that the magma records with metagabbro, metabasalt, andesite, granite, metarhyolite and granitic gneisses as the main rock assemblages developed in Riwan Chaka, Duguer, Gemuri, and Bensongco areas in central Qiangtang. The results of regional geological survey and chronology indicate that the Qiangtang had experienced a strong Early Paleozoic episodic magmatism, which can be subdivided into 5 stages, namely ~500 Ma, ~482 Ma, ~474 Ma, ~455 Ma and ~438 Ma respectively. In reference to previous geochemical and isotopic data, we preliminary speculate the Early Paleozoic magmatism in central Qiangtang may be a result of lithospheric extension on the northern margin of Gondwana after Pan-African orogenic movement. They constitute the Early Paleozoic crystalline basement of Southern Qiangtang-Baoshan Plate. The magmatic records play an importont role in constrainting the northern continental margin of Gondwana in the Qinghai-Tibet Plateau. |
| Key words: Tibet early Paleozoic magmatism Qiangtang basement Gondwana Tethys |