| 新疆兴地断裂带前寒武纪构造—岩浆—变形作用特征及其年龄 |
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| 引用本文： | 邓兴梁,舒良树,朱文斌,马东升,王博.新疆兴地断裂带前寒武纪构造—岩浆—变形作用特征及其年龄[J].岩石学报,2008,24(12):2800-2808. |
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| 作者姓名： | 邓兴梁 舒良树 朱文斌 马东升 王博 |
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| 作者单位： | 1. 南京大学矿床研究国家重点实验室,南京,210093;塔里木油田指挥部,库尔勒,841000
2. 南京大学矿床研究国家重点实验室,南京,210093 |
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| 基金项目： | 国家重点基础研究发展规划项目(编号: 2007CB411301)及国家自然科学基金(40573038)资助 |
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| 摘 要： | 本文分析了发生在塔里木北缘兴地断裂带的多期构造—岩浆演化特征。在此基础上,对三件前寒武纪火成岩样品进行了LA-ICP-MS锆石U-Pb定年,对兴地断裂带韧性变形构造进行了运动学分析。研究表明,兴地断裂带至少经历了4期地质构造演化; 其中,前寒武纪有两期。第一期发生在前南华纪,以强烈的挤压褶皱、韧性剪切变形和岩浆活动为特色; 第二期发生在南华纪—震旦纪,以广泛发育的双峰式火成岩、复式岩流和基性岩墙群为特征,伴随大规模冰川作用和地壳沉陷,对应Rodinia超大陆的裂解。LA-ICP-MS法锆石U-Pb年龄测定表明,辉长岩中的俘获锆石保留了3114±20Ma、2509±42Ma、1916±36Ma等多期古构造演化和岩浆活动信息,揭示研究区深部存在一个中-新太古代和古元古代的基底。双峰式火成岩测年数据证实,区内在820~800Ma(花岗岩脉,798±7Ma; 辉长辉绿岩墙,816±15Ma)发生过强烈的裂谷—岩浆活动。根据构造交切关系,兴地断裂带发生过两期前南华纪韧性变形;变形时代尚不清楚。运动学分析表明,第一期为朝北逆冲的推覆变形,第二期为右旋走滑变形。南华纪以来,区域变质和韧性变形微弱,为韧脆性变形。
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| 关 键 词： | 前寒武纪 构造—岩浆作用 年岭测定 运动学分析 兴地断裂带 |
Precambrian tectonism, magmatiam, deformation and geochronology of igneous rocks in the Xingdi fault zone, Xinjiang |
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| DENG XingLiang,SHU LiangShu,ZHU WenBin,MA DongSheng and WANG Bo.Precambrian tectonism, magmatiam, deformation and geochronology of igneous rocks in the Xingdi fault zone, Xinjiang[J].Acta Petrologica Sinica,2008,24(12):2800-2808. |
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| Authors: | DENG XingLiang SHU LiangShu ZHU WenBin MA DongSheng and WANG Bo |
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| Institution: | State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China |
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| Abstract: | This paper analyzed the polyphase tectono-magmatism features, the LA-ICP-MS zircon U-Pb ages on the Precambrian igneous rocks and cinematic sense of ductile shear for the Xingdi fault zone. Results suggest that four-phase tectonic evolution took placed in the Xingdi fault zone including two phases of Precambrian tectonism. The first event took place in pre-Nanhua Period that is characterized by strong folding, ductile shearing and magmatism. The second event occurred in the Nanhua-Sinian Period when bimodal magmatism, composite magmatic flow and basic dyke swarm were widely developed, followed by a large-scale glacier and depressions, which is corresponded with the Rodinia supercontinental breakup. The LA-ICP-MS zircon U-Pb dating data reveal that a Meso-Neoarchean and Paleoproterozoic basement is likely buried under the deep part of studied area, dating at 3114±20Ma, 2509±42Ma and 1916±36Ma on the captured zircons from gabbro. The dating results on the bimodal igneous rocks show that a peak bimodal magmatism took place during the 820~800Ma (798±7Ma for granitic dyke and 816±15Ma for diabase dyke). Cinematic analysis suggests that two phases of pre-Nanhua ductile deformation occurred in the Xingdi fault zone whereas the deformed age is not clear. The first belongs to a top-to-the north thrusting and the second-phase is a dextral strike-slip deformation along a sub-E-W direction. Since Nanhua Period, regional metamorphism and ductile shearing were very weak, only ductile-brittle deformation was widely developed. |
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| Keywords: | Precambrian Tectono-magmatism LA-ICP-MS dating Cinematic analysis Xingdi fault zone |
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