701铀矿床含矿岩石的沉积期后变化及矿床成因

本文在讨论岩石的沉积期后变化的基础上,对矿床成因提出了认识。该铀矿床的形成经历了沉积、成岩和后生过程。铀的主要矿源层为硅灰岩透镜体。硅灰岩透镜体的铀乎均含量比克拉克值高出1—2个数量级,其它伴生元素(Zn、Mo、Cu、Ni和As等)含量也较高。该矿床形成的过程是:在轻微变质、构造运动和火山作用参与下,地下深处聚集的水受热形成温度不太高的热水溶液,它对含铀硅灰岩透镜体岩石中的有益组分进行“活化”迁移,并在较短距离内于合适的环境(氧化-还原过渡带或还原带)中富集成矿。此矿床应归为岩生(或岩源)矿床类型。

THE POST-SEDIMENTATIONAL VARIATIONS OF ORE-BEARING ROCKS IN NO. 701 URANIUM DEPOSIT AND ITS METALLOGENESIS

On the basis of the discussion about post-sedimentational variations of rocks, the understanding of metallogencsis of the deposit is presented in this paper. The deposit was formed by sedimentary, diagenetic and epigeneticprocesses. Lenses of siliceous limestene are considered as main horizons of uranium source. Average uranium content in siliceous limestone lenses is 1-2 orders of magnitude higher than Clark value, and contents of its associated elements (Zn, Mo, Cu, Ni and As, etc. ) are relatively high. The forming process of the deposit is. under the participation of weak metamorrphism, tectonic movements and vol(?)anism, favourable composition in uraniferous siliceous limestone lenses was mobilized by thermal water which derived from deep heated underground water, and then Was to be concentrated and mineralized in appropriate environments redox transitional zone or reduction zone) at a shorter distance. This deposit should be classified as lithogene type.