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引用本文:和源,陈庆,朱利东,黄荣才,杨文光,陶刚,李超,柳树权. 西藏许如错地区古近纪盆地碎屑锆石U-Pb年代学充填记录分析[J]. 中国地质, 2019, 46(3): 557-574.
HE Yuan,CHEN Qing,ZHU Lidong,HUANG Rongcai,YANG Wenguang,TAO Gang,LI Chao,LIU Shuquan. Paleogene basin Zircon U-Pb Geochronology and basin record of Xurucuo Area in Tibet[J]. Geology in China, 2019, 46(3): 557-574(in Chinese with English abstract).
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西藏许如错地区古近纪盆地碎屑锆石U-Pb年代学充填记录分析
和源1,2, 陈庆2, 朱利东2, 黄荣才3, 杨文光2, 陶刚2, 李超2, 柳树权4
1.西南油气田分公司勘探开发研究院, 四川 成都 610041;2.成都理工大学沉积地质研究院, 四川 成都 610059;3.中国武装警察部队黄金第十一支队, 西藏 拉萨 850000;4.成都理工大学地球科学学院, 四川 成都 610059
摘要:
西藏许如错地区在国内鲜有学者研究,仅在少有的区域地质报告中出现。研究区内发育一套古近系碎屑岩沉积——日贡拉组,该地层在研究区局部具有一套火山岩夹层。文章通过对许如错地区古近系日贡拉组碎屑锆石的LA-ICP-MS U-Pb测年分析,结合周边盆地年龄结构及研究区沉积现象,进而追寻盆地沉积物物源和盆地充填记录。研究表明,日贡拉组为一套由粗变细最终又变粗的碎屑岩沉积夹少量火山岩,根据沉积原生构造和宏观剖面判断其主要是扇三角洲-浅湖相-扇三角洲的沉积环境;岩浆成因的碎屑锆石年龄峰值集中在127~134 Ma年龄段内,结合周缘年龄推断日贡拉组物源来自北-北西中部拉萨地块的早白垩世花岗岩。通过对研究区日贡拉组岩石组合、岩石地层序列、物源分析、沉积演化过程以及年代证据等方面的研究,发现日贡拉组的发育处于青藏高原俯冲碰撞隆升阶段和汇聚挤压隆升阶段。
关键词:  锆石U-Pb年代学  许如错地区  青藏高原
DOI:10.12029/gc20190308
分类号:P588.21
基金项目:中国地质调查局项目“西藏昂仁县北西H45E008011、H45E009011、H45E010010、H45E010011幅1:5万区域地质矿产调查”(DD2016008004)。
Paleogene basin Zircon U-Pb Geochronology and basin record of Xurucuo Area in Tibet
HE Yuan1,2, CHEN Qing2, ZHU Lidong2, HUANG Rongcai3, YANG Wenguang2, TAO Gang2, LI Chao2, LIU Shuquan4
1.Exploration Division, PetroChina Southwest Oil and Gas Field Company, Chengdu, 610041 Sichuan, China;2.Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059 Sichuan, China;3.China armed police forces gold eleventh detachment, Tibet, 85000;4.Institute of Earth Sciences, Chengdu University of Technology, Chengdu 610059 Sichuan, China
Abstract:
Aimed at exploration of provenance and basin filling records, the authors selected detrital zircons from Rigongla Formation of the Paleogene in the middle part of central Lhasa and conducted LA-ICP-MS detrital zircon U-Pb isotope analysis. The result reveals that Rigongla Formation is a kind of classic rocks which evolved from coarse to thin to coarse, with minor interbedded volcanic rocks. Judging from the sedimentary primary structure and the macroscopic section, its sedimentary environment was fan delta and shallow lake facies and fan delta. The peak age of magmatic origin of detrital zircon is concentrated in the 127-134 Ma age section. Combined with perimeter age, it is held that the provenance was from the early Cretaceous granite of NNW-trending central Lhasa block, and it was in the stage of subduction and collision uplift of the Tibetan Plateau and the stage of convergence and uplift.
Key words:  zircon U-Pb geochronology  Xurucuo area  Tibetan Plateau