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J4 ›› 2012, Vol. 18 ›› Issue (1): 106-116.

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Muscovite 40Ar/39Ar Dating of the Quartz Porphyry Veins from Northwest Guangxi, China, and its Geological Significance

Chen Maohong, Lu Gang, Li Xinhua    

  1. 1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological
    Science, Beijing 100037, China; 2. Institute of Regional Geological Survey of Guangxi, Guilin 541003, China
  • Received:2011-07-01 Revised:2011-11-03 Online:2012-03-20 Published:2012-03-20
  • Contact: Chen Maohong, Ph.D., Associate Research Scientist; E-mail: mhchen666@163.com
  • About author:Chen Maohong, Ph.D., Associate Research Scientist; E-mail: mhchen666@163.com

Abstract:

         The late Yanshanian magmatite in the Youjiang Fold Belt of western China is represented by basic-ultrabasic dyke
swarms and ultra-acid rock veins. The 40Ar/39Ar dating of muscovite phenocryst from quartz porphyry veins, which are located in the Bama-Fengshan-Linyun area of northwestern Guangxi, yields a plateau age of 95.59±0.68 Ma and an isochron age of 95.0±1.0 Ma for a NE-striking quartz porphyry vein in Longhuang of Fengshan county, and a plateau age of 96.54±0.70 Ma and an isochron age of 95.91±1.1 Ma for a NW-striking quartz porphyry vein in Bama county. These ages are interpreted as an emplacement age for quartz porphyry veins. The new data support that the Yanshanian magmatic activity concentrated on 80-100 Ma in the Youjiang Fold Belt and the surrounding area, indicating large scale extension and lithospheric thinning in western China during the late Cretaceous. Since the granitic magmatic activity of late Cretaceous was related to a large scale Sn-(Cu-Pb- Zn) mineralization in western China, it is worth considering the prospecting potential for Sn-(Cu-Pb-Zn) in the area where quartz porphyry occurs within the Youjiang Fold Belt. We further discuss whether Carlin-type gold deposits and other epithermal ore deposits are related to this episode of magmatic activity within the Youjiang Fold Belt.

Key words: muscovite 40Ar/39Ar age, quartz porphyry, Sn polymetallic mineralization, lithospheric thinning and extension, northwest Guangxi

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