西藏甲玛-卡军果推-滑覆构造系特征

摘要

通过矿区填图和路线调查,结合室内研究,指出:①甲玛-卡军果推-滑覆构造系由印度-欧亚板块碰撞引发,具有递进变形、自盆地中心向边部推覆、新盖老等特点,强变形于50 Ma±.②推覆体下盘为叶巴组构造岩系；推覆体由上侏罗统和下白垩统碳酸盐-碎屑沉积岩系构成,主体为轴面北倾的复式褶皱,自南而北分为前部带、中部带和后部带.滑覆构造系推覆形成的复背斜轴部高位岩块失稳向北滑覆形成,自南而北分为后部带、中部带和前部带.③导致矿区蚀变的主要岩浆活动发生于推覆强变形后的松弛期,上侵受近南北向基底断裂和推覆断裂联合控制,就位受控于前部带推-滑覆褶断系,其后发生多次构造-岩浆-成矿液叠加,造就甲玛铜多金属矿床.%Based on reconnaissance survey and geological mapping as well as comprehensive literature review and laboratory study, this paper presents the following conclusions: Firstly, the Jiama-Kajunguo thrust-gliding nappe tectonic system, which resulted from the Indo-Asia collision, deformed successively from the central part of the basin toward the margin, the new layer overlay the old one, and the greatest deformation occurred around 50 Mat. Secondly, the footwall block of the nappe is the Yeba group tectonite, the nappe consists of the upper Jurassic and rnlower Cretaceous carbonate and siliciclastics, the main part that is a complex fold with axial plane trends northward and can be divided into the fore-, mid- and post-parts from south to north structurally. The rock mass was located in the gliding nappe system at the top of the anticlinorium axis due to gravitational disequilibrium, which caused the hanging-wall block overlying the nappe to slip toward the north; the gliding nappe system is also divided into the fore-, mid- and post- parts from the south to the north in this paper. At last, the magmatic activities that induced the ore-forming alteration of the Jiama(Gyama) deposit happened during the releasing stage after the contraction stage of the thrust-gliding nappe tectonic system, and the upward migration of the magma was collaboratively controlled by the NS-trending basement faults and the thrusts. The magmatic rock that was emplaced finally in the fore-part of the thrust-gliding nappe tectonic system experienced multiple structural-magmatic-mineralization superimposition and generated the superlarge Jiama(Gyama) Cu polymetallic deposit.