| 阿拉善地块晚奥陶世—石炭纪的构造演化历史——来自北大山地区多期岩浆-变质-变形事件的约束 |
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| 引用本文： | 宫江华,张建新,王宗起,于胜尧,王东升.阿拉善地块晚奥陶世—石炭纪的构造演化历史——来自北大山地区多期岩浆-变质-变形事件的约束[J].岩石矿物学杂志,2018,37(5):771-798. |
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| 作者姓名： | 宫江华 张建新 王宗起 于胜尧 王东升 |
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| 作者单位： | 中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室;中国地质科学院地质研究所;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 |
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| 基金项目： | 国家自然科学基金项目（41702234） |
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| 摘 要： | 阿拉善地块西部的北大山地区识别出两期韧性变形构造,早期的韧性变形以从南(南东)向北(北西)逆冲为特征,晚期的韧性变形以近东西向左行剪切为特征。利用LA-ICP-MS锆石U-Pb测年方法,在记录早期韧性变形的片麻岩中获得锆石的变质年龄为422±1 Ma,代表晚志留世变质事件;在记录晚期韧性变形的2件二长花岗岩中获得锆石结晶年龄分别为326.2±1.2 Ma和323.8±2.6 Ma,代表早石炭世岩浆活动。结合前人研究成果,发现阿拉善地块西部北大山地区的两期韧性变形特征、变形时代与阿拉善地块东部巴彦乌拉山-狼山地区相似,同时阿拉善地块东、西部晚奥陶世-石炭纪多期岩浆活动的岩石类型、期次、地化及Nd同位素等特征也非常相似。以上特征表明,阿拉善地块东、西部经历了相同的构造演化历史,形成一条发育在早前寒武纪变质基底之上、呈近东西向弧形展布的晚奥陶世-石炭纪构造-岩浆岩带(西起桃花拉山,经北大山、诺尔公-巴彦乌拉山,东到狼山),其成因与古亚洲洋的俯冲造山事件密切相关。
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| 关 键 词： | 阿拉善地块 晚奥陶世-石炭纪岩浆岩 构造变形 锆石U-Pb定年 古亚洲洋 |
| 收稿时间： | 2018/2/26 0:00:00 |
Late Ordovician-Carboniferous tectonic evolutionary history of the Alxa Block: Constrained by the multistage magmatic-metamorphic-deformation events in Beidashan area |
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| GONG Jiang-hu,ZHANG Jian-xin,WANG Zong-qi,YU Sheng-yao and WANG Dong-sheng.Late Ordovician-Carboniferous tectonic evolutionary history of the Alxa Block: Constrained by the multistage magmatic-metamorphic-deformation events in Beidashan area[J].Acta Petrologica Et Mineralogica,2018,37(5):771-798. |
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| Authors: | GONG Jiang-hu ZHANG Jian-xin WANG Zong-qi YU Sheng-yao and WANG Dong-sheng |
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| Institution: | MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China,Key Laboratory of Submarine Geosciences and Prospecting Technique, Ministry of Education;College of Marine Geosciences, Ocean University of China, Qingdao 266100, China and MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | Two ductile deformations were identified in Beidashan area, which lies in the western Alxa Block. Early ductile deformation is characterized by top-to-the-north (northwest) ductile thrust structure, and a late Silurian metamorphic age of 422±1 Ma was yielded by the paragneiss which was related to the thrust deformation. Later ductile deformation was characterized by EW-trending sinistral shear, and two zircon U-Pb crystallization ages of 326.2±1.2 Ma and 323.8±2.6 Ma were yielded for two monzonitic granites which experienced the shear deformation. Combined with previous research on Alxa Block, a comprehensive comparison of the late Ordovician-Carboniferous magmatic-metamorphic-deformation events between the western and the eastern Alxa Block was made in this study. On the one hand, the characteristics and ages of two ductile deformations in Beidashan are similar to those of Bayanwulashan-Langshan which lies in the eastern Alxa Block. On the other hand, late Ordovician-Carboniferous magmatic rocks in the western and eastern Alxa Block also have similar rock types, ages as well as geochemical and Nd isotopic characteristics. All these characteristics indicate that the western and eastern Alxa Block went through the same tectonic evolution, and these authors also hold that a late Ordovician-Carboniferous tectonic-magmatic belt was developed in the early Precambrian metamorphic basement of the Alxa Block. This tectonic-magmatic belt extends from the Taohualashan in the west, through Beidashan, Nuoergong, Bayanwulashan, to the Langshan in the east and its origin was related to the continuous southward subduction of the Paleo Asian Ocean. |
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| Keywords: | Alxa Block Late Ordovician-Carboniferous magmatite tectonic deformation zircon U-Pb dating Paleo-Asian Ocean |
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