摘要
青海南山达不祖乎山北部一带的角孔变质岩系原划为早中三叠世隆务河组。通过野外实测地质剖面和路线地质调查,查明该套地层单元野外产出状态及岩石组合特征,并对其物质来源和形成时代进行分析,对进一步研究该区晚古生代-早中生代的构造演化具有重要意义。该套变质岩系为一套长石石英岩、石英岩、大理岩和黑云石英片岩组合,由下向上划分为3个岩段,叠置厚度大于3186.3m。根据碎屑锆石年龄分布特征,可大致划分为5个年龄组段,分别为250～304Ma、405～546Ma、649～1077Ma、1402～1620Ma和1861～2990Ma,其中250～304Ma可进一步划分为250～269Ma和289～304Ma两个亚组。综合前人研究资料与区域构造岩浆活动,将青海南山地区角孔变质岩的沉积时代限定为二叠纪,物源主要来自祁连造山带加里东期和晋宁期岩浆弧,柴北缘构造带海西期岩浆弧也提供了部分物质,晚古生代—早中生代经历了陆内裂陷、洋盆拉张及俯冲碰撞的构造演化过程。
The Jiaokong metamorphic rocks in northern Dabuzuhu Mountain of Nanshan area, Qinghai Province,were originally as.signed to Early-Middle Triassic Longwuhe Formation. Through detailed field work, the authors examined the output state and rockassemblage of the Jiaokong metamorphic rocks. Then the provenance and the formation age of this metamorphic suite were studied,with the purpose of investigating the evolution of the study area during Late Paleozoic to Early Mesozoic period. This metamorphicsuite was composed of arkosic sandstone, quartzite, marble,and mica-quartz schist. The suite has a total thickness of over 3186.3m, andcan be divided into 3 sections from bottom upward. The detrital zircon ages can be divided into 5 age clusters, i.e., 250-304Ma, 405-546Ma, 649-1077Ma, 1402-1620Ma and 1861-1990Ma. The 250-304Ma age cluster can be further divided into two sub-clusters of 250-269Ma and 289-304Ma. Taking into account of previous study results and regional tectonic-magmatic activities, the authors con.fined the depositional time limit of the Jiaokong metamorphic rocks to Permian, and its sedimentary sources might have mainly comefrom Caledonian and Jinningian magmatic arc in Qilian orogenic belt, with Hercynian magmatic arc in the structural belt of North Qa.idam basin also providing some sedimentary materials. Nanshan area of Qinghai experienced a complete process from intracontinentalrifting, basin extension and oceanic subduction to continental collision in the Late Paleozoic-Early Mesozoic period.
作者
李佐臣
裴先治
李瑞保
裴磊
张永明
王旭斌
刘成军
陈有炘
王盟
LI Zuochen;PEI Xianzhi;LI Ruibao;PEI Lei;ZHANG Yongming;WANG Xubin;LIU Chengjun;CHEN Youxin;WANG Meng(Key Laboratory of Western China＇s Mineral Resources and Geological Engineering, Ministry of Education/Key Laboratory for the Studyof Focused Magmatism and Giant Ore Deposits, MLR/Faculty of Earth Science and Resources, Chang＇an University, Xi＇an 710054,Shaanxi, China;Faculty of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;Faculty of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, Shandong, China;Shaanxi Mining Industry and Trade Company, Xi＇an 710054, Shaanxi, China)
出处
《地质通报》
CAS
CSCD
北大核心
2018年第4期570-588,共19页
Geological Bulletin of China
基金
中国地质调查局项目<祁连成矿带肃南-大柴旦地区地质矿产调查>(编号:DD20160012)
<青海省共和县曲什那地区1:5万J47E021017
J47E021018
J47E022018三幅区域地质矿产调查>(编号:12120114041201)
<青海省循化县道帏地区1:5万I48E002003
I48E003003两幅区域地质矿产调查>(编号:12120114018219)
<美武临潭构造解析与构造演化>(编号:DD2016007901)
国家自然科学基金项目<东昆仑东段晚古生代-早中生代构造演化与造山过程研究>(批准号:41472191)
<东昆仑东段东昆中蛇绿岩年代学及构造属性研究>(批准号:41502191)
关键词
青海南山
西秦岭造山带
南祁连构造带
变质岩
碎屑锆石
锆石U-PB年龄
Nanshan
Qinghai
Western Qinling orogen
Southern Qilian tectonic belt
metamorphism rocks
detrital zircon
zirconU-Pb ages
