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J4 ›› 2012, Vol. 18 ›› Issue (1): 150-157.

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40Ar-39Ar Plateau Ages of Biotite and Plagioclase from Xinwuli Granitoids in Tongling Area, Anhui Province and its Geological Significance

Wang Yonglei, Pei Rongfu, Wang Haolin, Qu Hongying, Li Jinwen   

  1. 1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological
    Sciences, Beijing 100037; 2. State Key Laboratory for Mineral Deposits Research (Nanjing University), Nanjing 210093, China
  • Received:2011-08-28 Revised:2011-10-09 Online:2012-03-20 Published:2012-03-20
  • Contact: Wang Yonglei, Ph. D.; E-mail: yongleiw@163.com
  • About author:Wang Yonglei, Ph. D.; E-mail: yongleiw@163.com
  • Supported by:

    南京大学内生金属矿床成矿机制研究国家重点实验室基金项目“长江中下游酸性侵入岩体的冷速率、热效应与其成矿强度的示
    范研究”(15-09-01);中国地质调查局危机矿山项目“铜陵市凤凰山铜矿深部岩石地球化学找矿预测”(200799093);中央
    级公益性科研院所基本科研业务费专项资金资助项目(K0907)及深部探测项目(Sinoprobe-03-01)共同资助

Abstract:

       Biotite and plagioclase samples from the quartz monzodiorite of Xinwuli granitoids yield 40Ar-39Ar plateau ages of
152.1±1.7 and 135±1 Ma. Samples from the granodiorite give 40Ar-39Ar plateau ages of 143.8±0.9 Ma and 140.4±0.9 Ma.
The similar ages suggest an important stage of Yanshanian magmatic activity in the Middle and Lower Yangtze regions. The 40Ar-39Ar age of biotite from quartz monzodiorite is older than the previous zircon U-Pb isotopic ages, which is probably due to excess argon. Together with the age data of Xinwuli granitoids, we obtain the cooling curves of the granodiorite and quartz monzodiorite. The cooling curves show that the cooling rates of Xinwuli granitoids have been fast since the Late Jurassic, indicating an extensional tectonism. The formation of Xinwuli granitoids may be related to the Late Mesozoic lithosphere thinning in Eastern China.

Key words: Xinwuli granitoids, 40Ar-39Ar;Cooling curve, Anhui Tongling, Fenghuangshan Cu deposit

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