胶东金矿形成期间地幔流体参与成矿过程的碳氧氢同位素证据

胶东地区发育有两种类型的金矿床，以玲珑，焦家，三山岛，乳山为代表的石英脉型-破碎蚀变岩型和以大庄子，蓬家夼为代表的胶莱盆地北缘滑脱破碎带内的角砾岩型金矿，本文选择了两种类型中的玲珑，三山岛和大庄子金矿床进行碳氧氢同位素测定。初步认为两类金矿属于同一成矿系统，它们形成于120Ma左右的华北克拉通岩石圈减薄和软流圈上涌期间，岩浆流体和地幔脱气与胶东世界级金矿的形成密切相关，在石英脉型-破碎蚀变岩型矿石中可见深刻的地幔流体和岩浆流体的“烙印”。形成于滑脱破碎带中的角砾岩金矿流体与中生代大气降水和海相碳酸盐岩发生了强烈的交换作用。

Mantle Fluids Involved in Metallogenesis of Jiaodong (East Shandong) Gold District: Evidence of C, O and H Isotopes

In the East Shandong peninsular, the largest gold base area in China, there are two types of gold ores, i.e., quartz vein_broken altered rock type and breccia type. The former, represented by the Linglong, the Jiaojia, the Sanshandao and the Rushan mines, is developed along the NNE_striking ductile_brittle shear zones within the uplift in the northern part of the Shandong peninsular and hosted in either Mesozoic granitoids or Precambrian metamorphic rocks. The latter, represented by the Dazhuangzi and the Pengjiakuang mines, occurs along the slumping zones between the Precambrian metamorphic rocks and the Cretaceous sandy conglomerate around the north of the Jiaolai basin in the southern part. Ten carbonate samples were collected from the carbonate veins (the latest stage of mineralization_alteration in the gold system) in Linglong, Jiaojia and Sanshandao and in Dazhuangzi for C_O_H isotopic analysis. The analytical results show that both types of the gold ores share the similar stable isotope components, implying the involvement of mantle or magmatic fluids in the gold mineralization process. Compared with those for the quartz vein_broken altered rock type, the ore_forming fluids responsible for the breccia ores seem to be mixed in a greater degree with meteoric water and marine carbonate. They were formed around 120 Ma, corresponding to the peak age of lithosphere thinning and delamination in the North China craton.