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西秦岭伯阳—元龙地区中泥盆统变砂岩碎屑锆石U-Pb年龄和地球化学特征及地质意义
投稿时间:2018-01-12  修订日期:2018-07-23  点此下载全文
引用本文:李亦飞,罗金海,徐欢,尤佳,陈冠旭.2018.西秦岭伯阳—元龙地区中泥盆统变砂岩碎屑锆石U-Pb年龄和地球化学特征及地质意义[J].地质论评,64(5):1087-1103
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作者单位E-mail
李亦飞 1)大陆动力学国家重点实验室西北大学地质学系西安710069 luojh@nwu.edu.cn 
罗金海 1)大陆动力学国家重点实验室西北大学地质学系西安710069  
徐欢 1)大陆动力学国家重点实验室西北大学地质学系西安710069  
尤佳 1)大陆动力学国家重点实验室西北大学地质学系西安710069
2)中国石油长庆油田分公司第二采油厂甘肃庆阳745100 
 
陈冠旭 1)大陆动力学国家重点实验室西北大学地质学系西安710069  
基金项目:本文为大陆动力学国家重点实验室科技部专项(编号:201210133)的成果。
中文摘要:对北秦岭—祁连结合部位伯阳—元龙地区一套变砂岩进行的碎屑锆石LA-ICP-MS U-Pb同位素测年结果表明,变砂岩碎屑锆石年龄的时间跨度极大(407~2483 Ma),有多个测点的年龄数据落入早泥盆世范围,说明变砂岩的沉积时代不应早于早泥盆世,结合区域地质资料将其形成时代确定为中泥盆世。变砂岩的主要物源是西秦岭造山带和扬子克拉通。结合地球化学特征推断变砂岩主体形成于活动大陆边缘构造背景,石英砂岩原岩中含有偏基性的火山物质,经过高绿片岩相—低角闪岩相变质作用形成富含黑云母和角闪石的变砂岩。本文的研究结果表明,中泥盆世天水—武山板块缝合带已经基本缝合,但未完全缝合,一方面导致源自扬子克拉通的碎屑物可以到达西秦岭北带,另一方面在西秦岭天水—武山构造带的部分区域可能仍有残余洋盆俯冲活动。
中文关键词:西秦岭  中泥盆统  变砂岩  地球化学  碎屑锆石U-Pb年代学
 
Detrital Zircon U-Pb Age, Geochemical Characteristics and Geological Significance of Meta-sandstones form Boyang—Yuanlong Area in The Western Qinling Orogenic Belt
NameInstitution
LI Yifei1)State Key Laboratory of Continental Dynamics (Northwest University),Department of Geology,Northwest University,Xi’an,710069
LUO Jinhai1)State Key Laboratory of Continental Dynamics (Northwest University),Department of Geology,Northwest University,Xi’an,710069
XU Huan1)State Key Laboratory of Continental Dynamics (Northwest University),Department of Geology,Northwest University,Xi’an,710069
YOU Jia1)State Key Laboratory of Continental Dynamics (Northwest University),Department of Geology,Northwest University,Xi’an,710069;2)No.2 Oil Production Company of Changqing Oil field Company of CNPC,Qingyang,Gansu, 745100
CHEN Guanxu1)State Key Laboratory of Continental Dynamics (Northwest University),Department of Geology,Northwest University,Xi’an,710069
Abstract:Objectives: The meta sandstones in Boyang—Yuanlong area located between Tianshui—Wushan suture zone and Xinyang—Yuanlong ductile shear zone. Up to now, the study of the meta sandstone in Boyang—Yuanlong area is not mature. Research of meta sandstone in Boyang—Yuanlong area could offer important information for the study of Qinling orogenic belt. Methods:Based on the clastic zircon LA-ICP-MS U-Pb dating and the analysis of geochemical data, we discussed the age and structural environment of the meta sandstone in Boyang—Yuanlong area. We Combined the zircon LA-ICP-MS U-Pb dating with geochemical data analysis and offer proof of the evolution of Tianshui—Wushan suture zone.Results:①The meta sandstone was formed in Middle Devonian, and the clastic sediment comes mainly from the Northern Qinling orogenic belt and Yangtze craton;②The provenance of meta sandstone was in Boyang—Yuanlong area is active continental margin in setting;③The closure of Tianshui—Wushan suture zone had been completed before Middle Devonian but not entirely.
keywords:western Qinling orogenic belt  Middle Devonian  meta sandstone  Geochemical  detrital zircon U-Pb Geochronology
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