| 藏北羌塘盆地基底变质岩的锆石SHRIMP年龄及其地质意义 |
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| 引用本文： | 谭富文,王剑,付修根,陈明,杜佰伟.藏北羌塘盆地基底变质岩的锆石SHRIMP年龄及其地质意义[J].岩石学报,2009,25(1):139-146. |
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| 作者姓名： | 谭富文 王剑 付修根 陈明 杜佰伟 |
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| 作者单位： | 中国地质调查局成都地质矿产研究所,成都,610081 |
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| 基金项目： | 国家专项《羌塘盆地油气资源战略选区调查与评价》项目（XQ-2004-06） |
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| 摘 要： | 羌塘盆地经受了青藏高原隆升事件等强烈的构造作用，盆地是否具有刚性结晶基底，对于油气的保存至关重要。长期以来对于该盆地是否具有前古生代的结晶基底，分歧较大。笔者新近在羌塘盆地中央隆起带北缘俄久卖发现的含夕线石和蓝晶石的片麻岩以及其附近发现的极浅变质的奥陶系地层，证实羌塘盆地具有变质结晶基底。本文进一步开展了片麻岩中锆石的SHRIMP年龄分析，获得了7组锆石年龄：2498~2374Ma 、1780 ~1666Ma、645~522Ma、465~420Ma、402~369Ma、270~233Ma和223~198Ma。通过CL图象对各组年龄锆石进行成因分析，并结合区域地质特征，认为1780 ~1666Ma为该片麻岩的主期变质年龄，羌塘盆地具有前寒武纪结晶基底，并对其余年龄组反映的构造热事件及其地质意义进行了讨论。
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| 关 键 词： | 羌塘盆地 结晶基底 前寒武纪 SHRIMP年龄 |
| 收稿时间： | 2008/4/29 0:00:00 |
| 修稿时间： | 9/8/2008 12:00:00 AM |
U-Pb zircon SHRIMP age of metamorphic rocks from the basement of the Qiangtang basin, northern Tibet, and its geological significance |
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| TAN FuWen,WANG Jian,FU XiuGen,CHEN Ming and DU BaiWei.U-Pb zircon SHRIMP age of metamorphic rocks from the basement of the Qiangtang basin, northern Tibet, and its geological significance[J].Acta Petrologica Sinica,2009,25(1):139-146. |
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| Authors: | TAN FuWen WANG Jian FU XiuGen CHEN Ming and DU BaiWei |
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| Institution: | Chengdu Institute of Geology and Mineral Resources, China Geology Survey, Chengdu 610081, China;Chengdu Institute of Geology and Mineral Resources, China Geology Survey, Chengdu 610081, China;Chengdu Institute of Geology and Mineral Resources, China Geology Survey, Chengdu 610081, China;Chengdu Institute of Geology and Mineral Resources, China Geology Survey, Chengdu 610081, China;Chengdu Institute of Geology and Mineral Resources, China Geology Survey, Chengdu 610081, China |
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| Abstract: | Whether exist crystalline basement or not? This is crucial to the petroleum preservation in the Qiangtang basin, where had undergone intense tectonism due to the Qinghai-Xizang plateau uplift. There has been much debate, for a long time, concerning the existence of pre-paleozoic crystalline basement. Recently, the authors found gneiss rocks containing sillimanite and kyanite in Ejiumai to the north of the central uplift belt in the Qiangtang basin. Combined with very low metamorphic Ordovician strata being found in this area, we conclude that there exist metamorphic crystalline basement in the Qiangtang basin. The zircon grains from the gneiss rocks yield a wide range of ages, and fall into seven groups: 2498~2374Ma, 1780 ~1666Ma, 645~522Ma, 465~420Ma, 402~369Ma, 270~233Ma and 223~198Ma. Zircon cathodoluminescence (CL) image analyses, in conjunction with regional geological characteristics, show that the main metamorphism of the gneiss rocks occurred from 1780Ma to 1666Ma, supporting the existence of Precambrian crystalline basement in the Qiangtang basin. This paper also discusses the other age groups and their geological implications. |
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| Keywords: | Qiangtang basin Crystalline basement Precambrian U-Pb zircon SHRIMP age |
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