甲玛-驱龙矿集区地壳结构及成矿指示意义  

Crustal structure and mineralization indications of the Jiama-Qulong deposits

作　　者：吴蔚 贺日政[1] 冀战波 牛潇 王超 李宗旭 WU Wei;HE Rizheng;JI Zhanbo;NIU Xiao;WANG Chao;LI Zongxu(Chinese Academy of Geological Sciences,Beijing 100037,China;Jiangri Communications Design and Research Institute Co.,LTD,Nanchang,Jiangzi 330052,China)

机构地区：[1]中国地质科学院,北京100037 [2]江西省交通设计研究院有限责任公司,江西南昌330052

出　　处：《地质学报》2023年第8期2534-2546,共13页Acta Geologica Sinica

基　　金：国家重点研发计划课题(编号2018YFC0604102);中国地质调查项目(编号DD20190015,DD202201643-04);西藏拉萨地球物理国家野外科学观测研究站资助项目(编号NORSLS20-05)联合资助的成果。

摘　　要：南拉萨地体位于印度大陆与亚欧板块陆陆碰撞的前缘,发育有大型的铜、钼、金等多金属斑岩型矿床,其地壳深部结构对于研究成矿构造背景和动力学模式有重要的约束作用。基于甲玛-驱龙矿集区及周边布置的33个宽频带地震台站资料,使用远震P波接收函数方法获得了矿集区的地壳结构和属性信息。地壳厚度和波速比扫描(H-κ扫描)发现矿集区平均地壳厚度为66 km,地壳平均波速比与地壳厚度呈负相关的关系,指示偏长英质物质的相对增加是地壳增厚的主要原因;共转换点叠加(CCP)结果发现矿集区下方没有双层Moho现象,推测矿集区缺失高速的基性下地壳,这也导致了地壳平均属性更偏向于长英质,推测矿集区地壳底部的基性下地壳发生过拆沉作用。新生下地壳是碰撞造山带斑岩铜钼金成矿的重要条件。本研究结果指示新生下地壳的重熔不仅破坏了陆陆碰撞形成的双莫霍面,还使得南拉萨地体地壳进一步分异,下部地壳发生镁铁质矿物堆晶而更偏基性,莫霍面增厚。As the main area where the Indian plate collides with the Eurasian plate,the southern Lhasa terrane has abundant mineral resources.The deep structure of the deposit has an important effect on the dynamic mode and mineralization structure.The P-wave receiver functions obtained by 33 broad band seismographs in Jiama-Qulong deposits were used to obtain the deep structures in the study area by H-κsuperposition and common conversion spot(CCP)stacking technique.The average Moho depth in the region is 66 km,and the Moho depth is inversely proportional to vP/vS,indicating the thickened felsic crust in the region.According to the CCP results,it is speculated that there is no Moho doublet under the deposits,indicating the removal of the lithospheric mantle.The results of this study indicate that the remelting of the juvenile crust under the deposit not only destroyed the Moho doublet formed by the collision of the Indian plate but also made the crust of Lhasa further fractionated,the lower crust was more mafic,the Moho phase was thickened.

关 键 词：接收函数 H-κ扫描 双莫霍面 斑岩铜矿 矿产勘查 

分 类 号：P612[天文地球—矿床学]