湘黔地区下寒武统热水喷流成矿矿物成因机制研究

对湖南、贵州剖面的上下岩层的硅质岩、磷块岩、重晶石岩、金属富集层的沉积海水的温度、深度、介质条件、生态条件进行研究,硅质岩沉积期古海水温度平均为84.81℃或87.27℃,磷块岩沉积期古海水温度平均为42.17℃,磷块岩的形成温度与硅质岩比较相似,<100℃,分别约为37~47℃、79~98℃。研究区水深变化在100~300 m之间。硅质岩、富硫化物黑色页岩(金属富集层)、重晶石生成于微碱性的介质环境。而磷块岩生成于微酸性-微碱性的介质环境。成岩成矿模型研究充分揭示亲基性元素Ni、Mo、V、Cr、PGE的存在与基性岩、超基性岩的成因联系。研究区域在早寒武世期间属于东特提斯海域, 中国南部板块和澳大利亚板块于早寒武纪分离期间所形成的深大断裂带,正可能是海水进行深部循环吸取镁铁质下地壳PGE形成富金属热卤水而在海底沉积的通道。

The Mineral Genesis and Mechanism Research of the Hot Water Exhalative Mineralization of the Lower Cambrian in Hunan and Guizhou Provinces

We carry out research to the temperature, depth, meta and ecological situation of the sedimentary marine water of the silicalite, phosphorite, barite rock, metal rich bed of the upper and lower rock bed of the profiles in Hunan and Guizhou provinces. The paleo-marine water temperature of the sedimentary stage of the silicalite is averaged as 84.81℃ or 87.27℃, that of the phosphorite is averaged as 42.17℃, and the rock-forming temperature of phosphorite is similar to the silicalite, smaller than 100℃, being respectively 37-47℃ and 79-98℃. The water depths vary within 100-300 m. Silicalite, sulfide-rich black shale(metal rich bed) and barite formed within the weak-alkaline meta environment. But the phosphorite formed within the weak-acidic and weak-alkaline meta environment. The rock-formation and mineralization model research thoroughly indicated the existence of the basic-phile elements Ni, Mo, V, Cr and PGE have genetic connections with the basaltic rock and super basic rock. The area belongs to the east Tetheyan sea during the early Cambrian, and the south China plate and the Australian plate formed the deep fault zone during the early Cambrian separation stage, which might be the corridor of the sea water carrying out deep cycle, absorbing the magnesium-iron lower-crust PGE, forming the rich-metal hot brine water and depositing in the sea bottom.