班公湖-怒江带、羌塘地块特提斯演化与成矿地质背景

早古生代—泥盆纪,研究区沉积环境以陆棚碎屑岩相和碳酸盐台地相为主,代表冈瓦纳大陆北缘和特提斯南侧的被动大陆边缘。石炭纪—二叠纪,本区进入特提斯南、北缘弧盆系统演化阶段,龙木错-双湖带北部、金沙江带南部和冈底斯带分别在石炭纪、二叠纪形成岩浆弧。中生代是特提斯南缘弧盆演化阶段,SSZ型蛇绿岩形成岩浆熔离型铬、镍、铂族金属矿床和热液型金矿。班公湖-怒江带特提斯在中侏罗世至早白垩世向南、北两侧俯冲并形成岩浆弧,该岩浆弧是重要的成矿带,形成斑岩铜矿、矽卡岩型磁铁矿和热液型多金属矿床。北羌塘东段侏罗纪弧后前陆盆地有利于形成沉积型、沉积-热液改造型和热液型铁、铜、锑、金矿床。晚白垩世碰撞作用主要与热液型矿床有关,分布范围较大,也可能存在晚白垩世至新生代碰撞阶段的斑岩铜矿。

Tethyan evolution and metallogenic geological background of the Bangong Co-Nujiang belt and the Qiangtang massif in Tibet

Early Paleozoic-Devonian sediments of the study area are mainly composed of shelf clastic rocks and platform carbonate, representing the northern margin of Gondwana and south Tethyan passive continental margin. Permian-Carboniferous archipelagos were formed to the south and north of the Tethyan ocean, resulting in the formation of magmatic arcs to the north of the Longmuco-Shuanghu belt and the south of the Jinshajiang and in the Gangdise zone one after another. Mesozoic archipelagos occurred to the south of the Tethyan ocean, where Cr, Ni and Pt group metallic type deposits of magmatic segregation occurred in the SSZ-type ophiolite. Petrological and geophysical evidence supports a bilateral subduction scenario that resulted in arc magmatism to the north and south of the Bangong Co-Nujiang suture zone. These magmatic arcs are the most important metallogenic belt for porphyry copper deposits, skarn-type magnetite deposits and hydrothermal polymetallic deposits. The Jurassic back arc and foreland basin to the northeastern Qiangtang favored the formation of depositional and hydrothermal alteration Fe-Cu-Sb-Au deposits. In the collisional stage of Late Cretaceous-Cenozoic period, hydrothermal deposits were widely distributed, and this stage was also a stage with the potential to form porphyry copper deposits.