西藏班公湖—怒江成矿带研究进展及一些新认识

Progress in the Study of Mineralization in the Bangongco-Nujiang Metallogenic Belt and Some New Recognition

狭义的班公湖—怒江成矿带的范围与班公湖一怒江洋盆残留的蛇绿混杂岩带一致，包括与超基性岩浆熔离作用相关的Cr，Fe，Ni等矿床；广义的班公湖-怒江成矿带包括缝合线南北两侧与班公湖-怒江洋俯冲、碰撞、碰撞后及陆内伸展作用有关的所有矿床和岩浆岩，其范围包括南羌塘地体南缘、班公湖一怒江缝合带、北-中拉萨地块的大部分区域，发育的矿床类型有斑岩型铜（金）矿、矽卡岩型铁（铜）矿、热液一蚀变岩型金矿和热液型钨矿等，涉及的动力学背景包括活动大陆边缘到板内的各个阶段。在2期重要的斑岩铜（金）成矿作用中，120—105MaBP矿床的形成与拉萨地体和南羌塘地体碰撞过程中深部俯冲洋壳物质的重熔有关，90～85MaBP矿床始于碰撞后阶段岩石圈地幔的底侵作用。一些关键的基础性科学问题，诸如大地构造背景（成矿环境）、岩浆作用特征、典型矿床成矿机制、矿床的保存与高原隆升之间的关系等，需要在今后的研究工作中予以关注。

The traditional Bangongco-Nujiang metallogenic belt overlap with the ophiolitic melange units remained in the Bangongco-Nujiang ocean including the Cr, Au, Fe mineralization controlled with magma liquation. On the other hand, the broad metallogenic belt involved the deposits which had been recognized the products of subduction or postsubduction lithospheric extension in the northern and southern sides of Bangongco-Nujiang subduction zone, which includes the southern edge of the southern Qiangtang, suture zone, part of the North and Middle Gangdese block. The types of deposits include porphyry copper （gold） deposits, skarn iron （copper） deposits, hydrothermal-altered rock type of gold deposits and hydrothermal type of tungsten deposits throughout the evolution of Bangongco-Nujiang ocean. The copper mineralization has two episodes at about 120 -105 Ma and 90 -85 Ma, respectively. The early stage of copper mineralization （120 - 105 Ma） likely formes by remelting of previously subduction-modified arc lithosphere. Moreover, the late stage of copper mineralization （90 - 85 Ma） could be triggered by posteollisional lithospheric mantle delamination. Some of key fundamental scientific problems, such as Tectonic background （metallogenic environment）, magmatism, metallogenic mechanism of typical deposits, the relationship between the preservation and plateau uplift, we need to pay attention to in the future work.