| 柴北缘牦牛山组火山岩锆石U Pb年龄及其地质意义 |
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| 引用本文： | 张耀玲,倪晋宇,沈燕绪,王超群,高万里,胡道功.柴北缘牦牛山组火山岩锆石U Pb年龄及其地质意义[J].现代地质,2018,32(2):329. |
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| 作者姓名： | 张耀玲 倪晋宇 沈燕绪 王超群 高万里 胡道功 |
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| 作者单位： | (1中国地质大学(北京) 地球科学与资源学院，北京100083；2中国地质科学院 地质力学研究所，北京100081；
3中国五矿集团公司 五矿勘查开发有限公司，北京100010；4国土资源实物地质资料中心，河北 廊坊065201) |
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| 基金项目： | 中国地质调查局柴达木盆地及周缘油气基础地质调查子项目(121201104000150007)。 |
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| 摘 要： | 柴北缘牦牛山组磨拉石建造不整合覆盖在前泥盆系之上，记录了该地区早古生代洋盆关闭的时间。对柴北缘牦牛山一带牦牛山组上部火山岩段两个流纹质熔结凝灰岩样品进行锆石U Pb同位素测定，两个样品的岩浆锆石206Pb/238U年龄加权平均值分别为(3965±24) Ma(n=17，MSWD=33)和(3958±12) Ma(n=20，MSWD=11)，均被解释为火山岩喷发年龄。结合东昆仑造山带牦牛山组测年结果，认为柴达木盆地周缘牦牛山组火山岩形成时代为晚志留世—晚泥盆世，且东昆仑与柴北缘加里东造山作用结束的时间均为早泥盆世之前，而非传统认为的晚泥盆世。
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| 关 键 词： | 牦牛山组 火山岩 锆石U Pb年龄 泥盆纪 柴北缘 |
Zircon U-Pb Ages and Geological Significance of Volcanic Rocks from Maoniushan Formation in the Northern Margin of Qaidam Basin |
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| ZHANG Yaoling,NI Jinyu,SHEN Yanxu,WANG Chaoqun,GAO Wanli,HU Daogong.Zircon U-Pb Ages and Geological Significance of Volcanic Rocks from Maoniushan Formation in the Northern Margin of Qaidam Basin[J].Geoscience——Journal of Graduate School,China University of Geosciences,2018,32(2):329. |
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| Authors: | ZHANG Yaoling NI Jinyu SHEN Yanxu WANG Chaoqun GAO Wanli HU Daogong |
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| Institution: | (1School of Earth Sciences and Resources, China University of Geosciences, Beijing100083, China;
2Institute of Geomechanics, Chinese Academy of Geoscience, Beijing100081, China;
3Minmetals Exploration and Development CoLtd, China Minmetals Corporation,Beijing100010, China;
4Cores and Samples Center of Land & Resources, Langfang,Hebei065201, China) |
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| Abstract: | The molasses of Maoniushan Formation rest unconformably on pre Devonian strata and record the closure time of the Early Paleozoic ocean in the northern margin of Qaidam Basin. This research determinates zircon U Pb isotopes from two rhyolite tuff samples of volcanic rock member of upper Maomiushan Formation of Maoniushan mountain, northern margin of Qaidam Basin. The weighted mean 206Pb/238U ages of magmatic zircons from two samples are (3965±24) Ma(n=17，MSWD=33)and (3958±12) Ma(n=20，MSWD=11), interpreted as the formation time of the volcanic rocks. Combining past dating results about Maoniushan Formation of East Kunlun orogenic belt, we concluded that the formation time of the Maoniushan Formation around Qaidam Basin should be Late Silurian to Late Devonian, and the Caledonian movement of East Kunlun and northern margin of Qaidam Basin ended before Early Devonian instead of Late Devonian, as traditional thought. |
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| Keywords: | Maoniushan Formation volcanic rock zircon U Pb age Devonian Northern Qaidam Basin |
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