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J4 ›› 2012, Vol. 18 ›› Issue (1): 158-163.

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Zircon U-Pb Dating of the Yishichun Mafic-Ultramafic Complex From Southern Qilian and its Geological Significance

YU Jiyuan, LI Xiangmin, MA Zhongping, WANG Guoqiang, TANG Zhuo, SUN Jiming, WU Peng   

  1. Xi,an Institute of Geology and Mineral Resource, China Geological Survey, Xi,an 710054, China
  • Received:2011-10-08 Revised:2011-11-14 Online:2012-03-20 Published:2012-03-20
  • Contact: Yu Jiyuan, Master D.; E-mail:yujiyuan111@163.com
  • About author:Yu Jiyuan, Master D.; E-mail:yujiyuan111@163.com

Abstract:

      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.

Key words: 基性-超基性侵入岩;LA-ICP-MS;锆石U-Pb定年;铜镍矿;南祁连

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