Metallogenesis in Tibetan collisional orogenic belt: Ⅰ. Mineralization in main collisional orogenic setting
HOU ZengQian1, YANG ZhuSen2, XU WenYi2, MO XuanXue3, DING Lin4, GAO YongFeng5, DONG FangLiu2, LI GuangMing6, QU XiaoMing2, LI GuangMing7, ZHAO ZhiDan3, JIANG SiHong2, MENG XiangJin2, LI ZhenQing2, QIN KeZhang7 and YANG ZhiMing1(1 Institute of Geology, CAGS, Beijing 100037, China; 2 Institute of Mineral Resources, CAGS, Beijing 100037, China; 3 China University of Geosciences, Beijing 100083, China; 4 Institute of Tibetan Plateau Research, CAS, Beijing 100085, China; 5 Shi jiazhuang College of Economy, Shijiazhuang 050031, Hebei, China; 6 Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, Sichuan, China; 7 Institute of Geology and Geophysics, CAS, Beijing 100029, China)
Metallogenesis of continents is an important research frontier in the present regional metallogeny, and its theoretic framework might be built up by deepening the understanding of metallogenesis in the collisional orogenic belt. However, metallogenesis in the collisional orogenic belt is rather poorly understood in comparison with metallogenesis in the plate tectonic setting. The Himalayan_Tibetan orogenic belt, which is characterized by the existence of large_scale, intense and young mineralizations as well as various kinds of large_size and weakly reformed deposits, is regarded as an ideal field for understanding the ore_forming processes in the collisional orogenic belt. Based on three years' systematical work on metallogeny in the Tibetan collisional orogenic belt, the authors have summarized the main ore_forming events and their temporal_spatial distribution, analyzed four important metallogenic belts and representative deposits as well as their plutonic processes and tectonic control factors and, on such a basis, set up a metallogenic model in the main collisional orogenic setting. The main collisional event lasted about 25 Ma (from 65 Ma to 41 Ma), resulting in the formation of the principal part of the Tibetan plateau orogenic belt characterized by the South Tibet foreland thrust belt, the Gangdese main collisional tectonic_magmatic belt, and the North Tibet fold_thrust belt. In company with the collisional orogenic event, many important magmatic events were developed, as evidenced by the existence of ① the crust_derived muscovite granite_potassic calc_alkaline granite assemblage (66～50 Ma), ② the positive ε_ Nd granite_gabbro assemblage (52～47 Ma), and ③ the mantle_derived basaltic subvolcanics_diabase assemblage, as well as widespread and thick Linzizong volcanics (64～43 Ma). The development of above magmatic activities suggests that the deep part of Tibetan plateau experienced in turn continental collision (65～52 Ma), breakoff of continental plate (52～42 Ma) and low angle underthrust of continental plate (40 Ma). At least four important ore_forming events occurred during the main collisional orogenic epoch, which included ① the Sn and rare metal event related to crust_derived granite, forming the Tengchong Sn and rare metal ore concentration area in east Tibetan plateau, ② the copper_gold_molybdenum event related to crust/mantle-derived granite, forming a Cu-Au ore belt 100 km long in south Gangdese, ③ the shear zone gold event related to collisional orogeny, forming the potential Au belt along the Yarlung Zangbo suture zone, and ④ the copper-gold event related to crust uplift, forming porphyry/epithermal transitional type Cu-Au deposits represented by the Xiongcun Cu-Au deposit.
【CateGory Index】： P611
【CateGory Index】： P611