Zircon U-Pb Dating of the Yishichun Mafic-Ultramafic Complex from Southern Qilian and its Geological Significance
详细信息
- 责任者：Yu Jiyuan (Xi’an Institute of Geology and Mineral Resource ; China Geological Survey ; Xi’an 710054 ; China) ; Li Xiangmin
- 刊名：Geological Journal of China Universities
- 出版年：2012
- 卷期：18(1)
- 关键词：基性岩 ; basic rocks ; 超镁铁质岩 ; ultramafics ; 铀—铅计时 ; U-Pb dating ; 祁连山 ; Qilian Mountains
- 页码：p.158-163
- 图表：3 illus., 1 table, 33 refs.
- 分类号：0801
- issnNo：ISSN1006-7493
- isbnNo：CN32-1440/P
摘要
The study area is located at the southern margin of the Middle Qilian,south of the Qinghai Lake-GuLei deep fault belt,which is a favorable area for copper-nickel deposits in Qilian metallogenic belt.Yishichun Copper-nickel ore occurs within the homologous and contemporaneous basic-ultrabasic intrusions,and copper-nickel mineralization is spatially and temporally related to the intrusive rocks.The cathodoluminescence(CL) images and the Th/U ratios of zircons from the basic-ultramafic rocks suggest that zircon crystals are of magmatic origin;The LA-ICP-MS U-Pb dating of these zircons yields a weighted mean age of 455.1±1.7 Ma.Therefore,the ore-bearing rock emplacement and copper-nickel mineralization occurred during the late Ordovician,and the metallogenic dynamic process was probably related to an ancient continental margin rifting.