| 东准噶尔琼河坝岛弧晚古生代地球动力学环境——来自和尔赛岩体暗色岩墙时空分布的证据 |
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| 引用本文： | 冯乾文,周可法,王金林.东准噶尔琼河坝岛弧晚古生代地球动力学环境——来自和尔赛岩体暗色岩墙时空分布的证据[J].地质科学,2015,0(4):1068-1082. |
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| 作者姓名： | 冯乾文 周可法 王金林 |
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| 作者单位： | 1. 中国科学院新疆生态与地理研究所, 中国科学院新疆矿产资源研究中心 乌鲁木齐 830011;
2. 新疆矿产资源与数字地质重点实验室 乌鲁木齐 830011 |
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| 摘 要： | 新疆东准噶尔地区地处阿尔泰、准噶尔和东天山等山系和构造单元的结合部位, 是研究中亚造山带(或称北亚造山区)构造演化的关键地区。以往的研究多集中于东准噶尔的岩石组合和地球化学组成, 相对缺乏构造变形尤其是中小尺度构造变形的研究。初步研究发现东准噶尔分布着大量的中基性暗色岩墙, 它们是后期岩浆侵入到前期构造裂隙中的产物, 可以从时空两个方面为构造裂隙的研究提供制约。本文结合地质资料和高分辨率遥感影像解译, 在琼河坝岛弧带中的和尔赛岩体(早泥盆世)中识别出来了874个暗色岩墙(晚石炭世-早二叠世)片段, 它们的走向以北西西-南东东向为主, 另外还有少数北东-南西和北西-南东走向的岩墙。通过岩墙的宏观变形特征可以推测, 北西西-南东东走向的岩墙形成于压张性裂隙之中, 北西-南东走向的岩墙形成于左行张剪裂隙之中, 北东-南西走向的岩墙形成于右行压剪裂隙之中。这些裂隙形成时平面最大主应力为北西西-南东东方向。结合岩体和岩墙的时代, 本文认为在晚泥盆世-早石炭世期间, 和尔赛岩体由于受到北西西-南东东方向的区域挤压作用而产生相应的裂隙, 可能标志着洋盆结束后碰撞作用的发生, 而晚石炭世-早二叠世暗色岩墙的普遍发育可能是后碰撞岩浆活动的标志。
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| 关 键 词： | 东准噶尔 琼河坝 中基性岩墙 地球动力学环境 |
| 收稿时间： | 2015-01-20 |
| 修稿时间： | 2015-01-20; |
The Late Paleozoic geodynamic environment of Qiongheba arc,eastern Junggar: Evidence form spatial and temporal distribution patterns of dark dykes in Hersai pluton |
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| Feng Qianwen,Zhou Kefa,Wang Jinlin.The Late Paleozoic geodynamic environment of Qiongheba arc,eastern Junggar: Evidence form spatial and temporal distribution patterns of dark dykes in Hersai pluton[J].Chinese Journal of Geology,2015,0(4):1068-1082. |
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| Authors: | Feng Qianwen Zhou Kefa Wang Jinlin |
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| Institution: | 1. Xinjiang Institute of Ecology and Geography, Xinjinag Research Center for Mineral Resources, Chinese Academy of Sciences, Ürümqi 830011;
2. Xinjiang Key Laboratory of Mineral Resources and Digital Geology, Ürümqi 830011 |
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| Abstract: | The eastern Junggar, located among the Altai, eastern Tianshan and Junggar Basin, is the key area to understand the tectonic evolution of the central Asian orogenic belt(also called North Asian orogenic region). Previous studies mostly focused on rock associations and geochemical characteristics of the eastern Junggar, but the structural deformations, specially the deformations in middle-small scale, were rarely involved. This study initially find that there are large amount of dark-colored mafic dykes emplaced in eastern Junggar, they were formed by mafic magma from the deep intruding into the earlier formed fractures in the host rocks. Dykes can provide both temporal and spatial constrains on the mechanism of structural fractures. In Hersai pluton, a granite pluton of Qiongheba arc in eastern Junggar, 874 segments of dark dykes are distinguished by high-resolution remote sensing interpretation and previous regional survey. The Hersai pluton was formed in Early Devonian and dykes were formed in Late Carboniferous to Early Permian. The majority of their strikes are NWW-SEE and minority strikes are NE-SW and NW-SE. Macroscopic deformations of the dykes reveal that the NWW-SEE trending dyke-fractures are extensional caused by NWW-SEE compression, the NE-SW dyke-fractures are compressional-dextral, and the NW-SE dyke-fractures are extensional-sinistral. Combined these dyke-fractures with different trending into consideration, they were caused by NWW-SEE regional compression. This study reveals that during the Late Devonian to the Early Carboniferous, Hersai pluton was compressed by NWW-SEE maximum principal stress and different groups of fractures were formed, which may be caused by intercontinental collision after termination of ocean basin. The occurrence of mafic dykes in the Late Carboniferous to the Early Permian may be caused by so-called post-collisional extensions. |
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| Keywords: | Eastern Junggar Qiongheba arc Mafic dykes Geodynamic environment |
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