| 西藏冈底斯带叶巴组火山岩同位素地质年代 |
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| 引用本文： | 耿全如,潘桂棠,王立全,朱弟成,廖忠礼.西藏冈底斯带叶巴组火山岩同位素地质年代[J].沉积与特提斯地质,2006,26(1):1-7. |
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| 作者姓名： | 耿全如 潘桂棠 王立全 朱弟成 廖忠礼 |
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| 作者单位： | 成都地质矿产研究所,四川,成都,610082 |
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| 基金项目： | 国家“973”项目“印度与亚洲大陆主碰撞带成矿作用(2002CB412609)”，中国地质调查局项目“西藏南部空白区地质综合研究项目(1212010310102)” |
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| 摘 要： | 西藏达孜县附近的叶巴组主要为一套浅变质玄武岩、英安岩、酸性凝灰岩夹少量紫红色砂岩。对叶巴组英安岩的锆石SHRIMP的U-Pb测年,获得181.7±5.2Ma的年龄值,可代表达孜地区叶巴组的年龄。地质年代学研究和岩石组合特征显示,叶巴组应该分为上、下两部分。达孜县附近的一套火山岩时代为早侏罗世;工布江达县、桑日县和墨竹工卡县之间的叶巴组为一套酸性火山岩夹碎屑岩、碳酸盐岩,形成时代为中、晚侏罗世。叶巴组火山岩可能是班公湖-怒江特提斯洋向南的俯冲、消减的产物。本次SHRIMP测试获得变质年龄值131.9±5.5Ma,代表早白垩世的变质事件,反映燕山期冈底斯带强烈的岩浆活动对早期地质记录的叠加和改造。
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| 关 键 词： | 冈底斯带 早侏罗世 叶巴组 火山岩 年龄 西藏 |
| 文章编号： | 1009-3850（2006）01-0001-07 |
| 收稿时间： | 2006-01-15 |
| 修稿时间： | 2006年1月15日 |
Isotopic geochronology of the volcanic rocks from the Yeba Formation in the Gangdise zone,Xizang |
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| GENG Quan-ru,PAN Gui-tang,WANG Li-quan,ZHU Di-cheng,LIAO Zhong-li.Isotopic geochronology of the volcanic rocks from the Yeba Formation in the Gangdise zone,Xizang[J].Sedimentary Geology and Tethyan Geology,2006,26(1):1-7. |
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| Authors: | GENG Quan-ru PAN Gui-tang WANG Li-quan ZHU Di-cheng LIAO Zhong-li |
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| Institution: | Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, Sichuan, China |
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| Abstract: | The Yeba Formation in the Dagze region,Xizang is built up of slightly metamorphosed basalt,dacite and acidic tuff intercalated with purplish red sandstone.The dacite gives a SHRIMP U-Pb zircon age of 181.7±5.2 Ma,which may represent the age of the Yeba Formation.The examination of geochronology and rock associations suggests the subdivision of the Yeba Formation into two parts:upper and lower.The volcanic rocks in the Dagze region may be traced back to the Early Jurassic.The acidic volcanic rocks intercalated with clastic rocks and carbonate rocks from the Yeba Formation intermediate between Gongbo''gyamda,Sangri and Maizhokunggar are Middle and Late Jurassic in age.The volcanic rocks in the Yeba Formation may be considered as the products originated from southward subduction and consumption of the Tethyan Ocean in the Bangong-Nujiang suture zone.The SHRIMP U-Pb zircon age of 131.9±5.5 Ma for the metamorphic rocks represents that of the metamorphism event during the Early Cretaceous,which may largely be the expressions of superimposition and reworking of early geological records caused by intense magmatism in the Gangdise zone during the Yanshanian. |
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| Keywords: | Gangdise zone Early Jurassic Yeba Formation volcanic rock age Xizang |
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