郭远新,王芳.西昆仑东段尼沙-奥木夏蛇绿混杂岩物质组成与构造环境[J].西北地质,2019,52(3):14-25
西昆仑东段尼沙-奥木夏蛇绿混杂岩物质组成与构造环境
Composition and Tectonic Environment of Nisha-Aomxia Ophiolitic Mélange in the Eastern Section of West Kunlun
投稿时间:2019-01-05  修订日期:2019-03-27
DOI:10.19751/j.cnki.61-1149/p.2019.03.002
中文关键词:  西昆仑东段;和田地区;蛇绿岩;构造环境
英文关键词:West Kunlun;Hetian area;ophiolite;tectonic setting
基金项目:新疆地勘基金项目管理中心2016年度中央返还两权价款项目“新疆西昆仑卡浪大克一带1∶5万J44E022007、J44E022008、J44E023007、J44E023008、J44E024007、J44E024008六幅区域地质调查”(K16-1-LQ06)
作者单位
郭远新 新疆维吾尔自治区地质勘查基金项目管理中心, 新疆 乌鲁木齐 830001 
王芳 新疆维吾尔自治区地质勘查基金项目管理中心, 新疆 乌鲁木齐 830001 
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中文摘要:
      蛇绿岩作为消失的古海洋岩石圈的残片,是恢复造山带洋陆转换和构造演化历史的重要指示标志。西昆仑库地-其曼于特蛇绿构造混杂岩时空分布和产出规模一直是区域上早古生代期间构造演化过程的关键要素。西昆仑东段和田地区的尼沙-奥木夏出露有较为完整的蛇绿岩组合,主要由地幔橄榄岩、堆晶辉长岩、火山熔岩、深海复理石细碎屑岩等岩片构成。蛇绿岩中的锆石LA-ICP-MS U-Pb同位素测年成果显示:辉长岩为(450±59)Ma、(432.0±5.7)Ma;玄武岩为(480.3±6.4)Ma,英安岩为(506.4±5.5)Ma,这些同位素测年成果表明蛇绿岩可能形成于早古生代。通过对该套蛇绿岩的各端元开展详细的地质和地球化学研究,结合与其相伴发育的一套岛弧钙碱性火山岩组合特征,可知其形成于俯冲带相关构造背景的特征(SSZ型)。综合分析表明,尼沙-奥木夏蛇绿岩为库地-其曼于特蛇绿构造混杂岩东延部分,其对揭示西昆仑东段构造演化格局及过程具有重要意义。
英文摘要:
      Ophiolite, as the remnant of the disappeared paleo-oceanic lithosphere, is an important indicator to reconstruct the history of oceanic-continental transition and tectonic evolution in orogenic belt. The spatial-temporal distribution and outcrop scale of the Kudi-Qimanyute ophiolitic tectonic mélange have been the key to understand the tectonic evolution of the western Kunlun during Early Paleozoic. The ophiolite association is well occurred in the Nisha-Aomuxia area of Hetian City and the eastern part of West Kunlun, which is mainly composed of mantle peridotite, cumulate gabbro, volcanic lava and abyssal flysch. LA-ICP-MS zircon U-Pb analyses yield the magma crystallization ages of (450±59) Ma and (432.0±5.7) Ma for the gabbro, (480.3±6.4) Ma for the basalt and (506.4±5.5) Ma for the dacite. These geochronological data indicate that the Nisha-Aomuxia ophiolite was formed in Early Paleozoic. Based on detailed geological and geochemical studies on different rock units of the ophiolite, and combined with the characteristics of spatially related island arc calc-alkaline volcanic rock association, it's suggested that the Nisha-Aomuxia ophiolite belongs to SSZ-type and was formed in a subduction-related setting. Comprehensive analysis shows that the Nisha-Aomuxia ophiolite is an eastward extension of the Kudi-Qimanyute ophiolitic tectonic mélange, which can provide important insights into the tectonic evolution of the eastern part of West Kunlun.
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