贵州下寒武统黑色岩系多金属矿层成矿物质来源的铅同位素示踪

Pb isotopic constraints on the source of ore-forming materials of polymetallic layer of black rock series,Guizhou

为探讨贵州黑色岩系多金属矿层的成因和成矿物质来源,文章对镇远江所出露的黑色岩系多金属层铅同位素进行了测试。结果表明,黑色岩系多金属矿石铅来源于壳源混合铅,且具有富铀铅贫钍铅的特点,下寒武统牛蹄塘组的下伏灯影组富铀铅而贫钍铅的化学沉积物可能提供了较多的成矿物质。成矿物质主要来源于地壳,具有地幔铅混染的特点,是岩浆作用,化学沉积作用,海底热水作用共同参与的结果。黑色岩系多金属矿层的形成是多种成矿作用过程叠加的结果,具有多来源,多期次的成矿特点。

In order to discuss the genesis and sources of the ore-forming materials of polymetallic layer of black rock series in Guizhou, the paper analyzed the isotopic compositions of polymetallic layer of black rock series exposed in Jiangsuo, Zhenyuan County. The results have shown that lead mixture of crust is the source of polymetallic ore lead of black rock series, there is the character of rich uranium lead and lean thori- um lead, more metallogenetic materials might have been provided by chemical sedimentations of rich urani- um lead and lean thorium lead of underlying Dengying formation of the lower Cambrian Niutitang formation. The lead source of ore-forming materials are mixture of mantle and crust being the main source, being com- bined results of magmatism, chemical sedimentation and ocean hydrothermal sedimentation participated in. The formation of polymetallic layer of black rock series is the result of superimposition of multiple minerali- zation, been characterized by the multiple source and polyphase episode.