地质通报2012，Vol.31Issue(9)：1469-1481,13.
西秦岭造山带北缘大草滩群物源研究——LA-ICP-MS碎屑锆石U-Pb年龄证据
A study of the material source of Dacaotan Group in the northern margin of West Qinling orogenic belt: LA-ICP-MS U-Th-Pb age evidence of detrital zircons
摘要
Abstract
With clastic rocks of Late Devonian Dacaotan Group on the north margin of West Qinling orogenic belt in eastern Gansu as the study object, the authors used LA-ICP-MS zircon U-Pb isotope geochronologic method to explore the material source of Dacaotan Group. The results show that the age spectra of Dacaotan Group detrital zircon can be evidently divided into four groups: 422-518Ma, 756-887Ma, 1100-1231Ma and 2417-2736Ma? of which, the 422-486Ma age data possess the largest proportion, accounting for about 67% of the total data, having relatively concentrated ages, and showing a strong peak. The other ages possess a smaller proportion. The group of 422-518Ma indicates that its material sources were mainly from northern margin of western Qinling orogenic belt and Qilian orogenic belt in adjacent regions. The compositional ages suggest a sedimentary response to the orogenic erosion of a series of igneous rocks caused by the northward subduction and collision of mid-southern Qilian and western-Qinling micro-blocks in the Caledonian period. Detrital zircon U-Pb isotopic age group of 756-887Ma suggests that the material sources might have mainly come from the Qilian orogenic belt and northern margin of western Qinling orogenic belt. The age group of 1100-1231 Ma implies that the material sources might have come from Qilian orogenic belt, and 2417-2736Ma age group indicates that the material sources were probably derived from the basement of north Qilian orogenic belt and northern margin of western Qinling orogenic belt, with part of the material sources probably derived from the North China plate basement. A comprehensive analysis shows that the material sources of Dacaotan Group were much more complicated and characterized by obvious diversity, derived from the northern margin of western Qinling orogenic belt, Qilian orogenic belt and the basement of North China plate. The Qilian orogenic belt and the northern margin of western Qinling orogenic belt made significant source contribution to the sedimentation of Dacaotan Group, with the Qilian orogenic belt possessing the dominant role.关键词
大草滩群/LA-ICP-MS锆石U-Pb年龄/西秦岭北缘/物源Key words
Dacaotan Group/ LA-ICP-MS zircon U-Pb ages/ northern margin of West Qinling/ material source分类
天文与地球科学引用本文复制引用
吴树宽,王银川,裴先治,李佐臣,李瑞保,裴磊,陈有炘,高景民,刘成军,魏方辉..西秦岭造山带北缘大草滩群物源研究——LA-ICP-MS碎屑锆石U-Pb年龄证据[J].地质通报,2012,31(9):1469-1481,13.基金项目
国家自然科学基金项目《西秦岭北缘变形构造解析及其祁连-秦岭构造交接关系研究》(批准号:4092136)、中央高校基本科研业务费专项资金项目《中央造山系(中西段)关键构造部位复合造山作用研究》(编号:CHD2011TD020)和中国地质调查局地质调查项目《天水市幅1:25万区域地质调查(修测)》(编号:200013000154) （批准号:4092136）
