ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    纳米比亚达马拉造山带地质、构造演化特征与铀成矿作用

    Geological, Tectonic Evolution Characteristics and Uranium Mineralization of the Damara Orogenic Belt in Namibia

    • 摘要: 纳米比亚达马拉造山带是新元古代—早古生代泛非造山活动在西南非洲的体现,笔者系统梳理达马拉造山带内地质单元、岩浆作用、变质活动、构造动力学机制和铀矿成矿作用特征。该造山带主要由北部地体、北带边缘、北部带、中央带、南部带、南带边缘及南部前陆7个地质单元组成。依据板块运动特征,将其构造演化划分为板内裂谷期(750 Ma)、持续扩张期(730~600 Ma)、洋陆俯冲期(580~560 Ma)、俯冲碰撞期(550~540 Ma)及碰撞晚期(530~460 Ma)5个阶段。造山带内赋存大量的铀矿资源,主要形成于510~490 Ma,其成因与碰撞晚期构造及岩浆活动密切相关,成矿专属性特征明显。根据对现有资料的分析及总结,笔者认为富U的前达马拉基底是白岗岩型铀矿成矿物质的主要来源,成矿母岩浆是同化混染与分离结晶共同作用的结果,构造活动为富U岩浆的侵位及富集沉淀提供有利场所。

       

      Abstract: The Damara orogeny in Namibia is part of the Neoproterozoic to early Paleozoic Pan–African orogeny in Southwest Africa. This paper systematically combs the characteristics of geological units, magmatism, metamorphism, tectonic dynamics mechanism and uranium mineralization in the Damara orogenic belt. The orogenic belt is mainly composed of seven geological units: the northern terrane, the northern margin, the northern zone, the central zone, the southern zone, the southern margin, and the southern foreland. Based on the characteristics of plate movement, the tectonic evolution of this orogenic belt has been divided into five stages, mainly including intraplate rift (750 Ma), continuous expansion (730~600 Ma), ocean–continent subduction (580~560 Ma), subduction collision (550~540 Ma) and late collision (530~460 Ma). This orogenic belt is endowed with plenty of uranium resources, mainly formed at 510~490 Ma, closely related to tectonic and magmatic activities in origin, with a peculiar metallogenic specialization. According to the analysis and summary of existing data, this article believes that the pre–Damara basement, which is rich in uranium, is the main source of ore–forming materials of the alaskaite type uranium deposit. The parent magma related to mineralization is the result of combined action of assimilation, contamination and fractional crystallization. The tectonic activity provides a favorable site for the emplacement, enrichment and precipitation of the uranium–rich magma.

       

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