西藏班公湖—怒江成矿带中段岩浆演化及其金矿成岩成矿动力学模式

MAGMATIC EVOLUTION AND METALLOGENIC MODEL OF GOLD DEPOSITS IN THE MIDDLE PART OF BANGONGHU-NUJIANG METALLOGENIC BELT, TIBET

从岩浆活动的空间分布及演化特征的角度,研究了岩浆活动与金矿成矿、地球动力学之间的内在联系。提出了金矿成岩成矿具有统一性和周期性的6阶段演化的动力学模式。即T1-T2,羌塘地体、冈底斯地体雏形阶段;T3-J1,班怒洋盆、雅江洋盆雏形阶段;J2-J13洋盆不断扩张形成蛇绿岩套及与其有关金矿床阶段;J23-K1、洋盆闭合、地体拼合、雅江洋盆北向俯冲,形成变质热液型金矿床或与花岗岩有关的Au(Cu)、Sn、Pb、Zn成矿系列;K2-E2雅江蛇绿岩侵位阶段;E2以来,地幔柱形成高原隆升,砂金矿形成阶段。

Mineralizing processes of gold deposits were controlled by the strong and widespread magmatic activities in the middle part of Bangonghu-Nujiang matallogenic belt . The internal relations of magmatic activities , mineralizing processes and earth dynamics have been studied on the base of study of spatial distribution and evolution of magmatic activities . A unified and periodic dynamic model which included six periods has been proposed . The first period is the embryonic period of Qiangtang terrane and Gangdisi terrane in the early and middle Triassic . The second is the embryonic period of Bangonghu-Nujiang ocean basin and Yaluzangbujiang ocean basin between late Triassic and early Jurassic . The third is between the late part of early Jurassic and the middle Jurassic when the ocean basin extended and ophiolite suite and its relational gold deposits had been formed . The fourth is between the middle part of late Jurassic and early Cretaceous when the ocean basin closured , the terranes matched , Yaluzangbujiang ocean basin subducted to the north and the metamorphic hydrothermal solution and the Au(Cu)-Sn-Pb-Zn mineralization series related to granite had been formed . The fifth is between the middle Cretaceous and late Palaeogene when Yaluzangbujiang ophiolite emplaced . The last period is between late Palaeogene and now when mantle plume formed , plateau uplifted and gold placer formed .