| 西藏改则县拉果错蛇绿岩构造属性:来自岩石学、地球化学、年代学及Lu-Hf同位素的制约 |
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| 引用本文： | 徐建鑫,李才,范建军,王明,解超明.西藏改则县拉果错蛇绿岩构造属性:来自岩石学、地球化学、年代学及Lu-Hf同位素的制约[J].地质通报,2018,37(8):1541-1553. |
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| 作者姓名： | 徐建鑫 李才 范建军 王明 解超明 |
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| 作者单位： | 武警黄金第三支队;吉林大学地球科学学院 |
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| 基金项目： | 国家自然科学基金项目《青藏高原羌塘南部埃迪卡拉纪地层研究》（批准号：41602230）、《班公湖-怒江洋早白垩世演化：来自复理石沉积的制约》（批准号：41702227）和中国地质调查局项目《班公湖-怒江成矿带铜多金属矿资源基地调查》（编号：DD20160026）、《冈底斯-喜马拉雅铜矿资源基地调查》（编号：DD20160015） |
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| 摘 要： | 拉果错蛇绿岩是狮泉河-阿索-嘉黎蛇绿岩带中出露最完整的蛇绿岩组合之一,对恢复和反演该缝合带所代表洋盆演化具有重要意义。然而,目前拉果错蛇绿岩的成因及构造环境还不清楚,时代也存在争议。选择拉果错蛇绿岩中的斜长花岗岩和堆晶辉长岩作为研究对象,开展了野外勘查及剖面的测制,以及地球化学、LA-ICP-MS锆石U-Pb定年及Lu-Hf同位素研究,并结合区域地层、岩浆岩等相关资料,探讨了拉果错蛇绿岩的构造属性。拉果错斜长花岗岩和辉长岩野外呈整合接触,地球化学特征表明二者具有同源性,具有与E-MORB(富集大洋中脊玄武岩)相似的稀土元素配分形式和微量特征;Lu-Hf同位素显示岩浆源区为亏损地幔,由多种组分组成,可能来源于亏损地幔和Ⅱ型富集地幔二组分混合的地幔源区;斜长花岗岩和辉长岩LA-ICP-MS锆石U-Pb定年分别获得184.1±0.79Ma和183.5±2.2Ma的谐和年龄,代表了拉果错蛇绿岩的形成时代。研究表明,拉果错蛇绿岩形成于具有强烈大洋中脊玄武岩特征的弧后盆地环境。
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| 关 键 词： | 青藏高原 狮泉河-永珠-嘉黎蛇绿岩带 拉果错蛇绿岩 |
| 收稿时间： | 2018/1/10 0:00:00 |
| 修稿时间： | 2018/4/20 0:00:00 |
Tectonic property of the Laguocuo ophiolite in Gerze County, Tibet: Constrains from petrology, geochemistry, LA-ICP-MS zircon U-Pb dating and Lu-Hf isotope |
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| XU Jianxin,LI Cai,FAN Jianjun,WANG Ming and XIE Chaoming.Tectonic property of the Laguocuo ophiolite in Gerze County, Tibet: Constrains from petrology, geochemistry, LA-ICP-MS zircon U-Pb dating and Lu-Hf isotope[J].Geologcal Bulletin OF China,2018,37(8):1541-1553. |
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| Authors: | XU Jianxin LI Cai FAN Jianjun WANG Ming and XIE Chaoming |
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| Institution: | No.3 Gold Geological Party, CAPF, Harbin 150006, Heilongjiang, China,College of Earth Science, Jilin University, Changchun 130061, Jilin, China,College of Earth Science, Jilin University, Changchun 130061, Jilin, China,College of Earth Science, Jilin University, Changchun 130061, Jilin, China and College of Earth Science, Jilin University, Changchun 130061, Jilin, China |
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| Abstract: | Laguocuo ophiolite is one of the most complete ophiolite combinations in the Shiquanhe-Yongzhu-Jiali ophiolitic belt, and has great significance for restoring the evolution of the oceanic basin. However, the studies of the Laguocuo ophiolite are poor, resulting in the unclear genesis and controversial age. In this paper, the authors conducted field survey, profile measurement, geochemical survey, LA-ICP-MS zircon U-Pb dating and Lu-Hf isotope analysis on the plagioclase granite and gabbro cumulates of the Laguocuo ophiolite so as to study the tectonic property of the Laguocuo ophiolite. Plagioclase granite and gabbro cumulate of Laguocuo ophiolite exhibit direct contact in the field, and their geochemistry data show that they are of the same source with similar REE patterns that are similar to features of the E-MORB. Lu-Hf isotope analysis shows that their magmatic source is the depleted mantle, and shows a plurality of components, which might have resulted from the mixing of DM and EM2. Zircon LA-ICP-MS UPb dating yielded concordia ages of 184.1±0.79Ma and 183.5±2.2Ma. The authors have reached the conclusion that Laguocuo ophiolite was formed in a back-arc ocean basin with strong MORB characteristics. |
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| Keywords: | Tibetan Plateau Shiquanhe-Yongzhu-Jiali ophiolitic belt Laguocuo ophiolite |
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