陕西镇巴—重庆城口锰矿沉积环境及成矿作用

Sedimentary Environment and Mineralization for the Manganese Ore Deposits from Zhenba,Shaanxi to Chengkou,Chongqing

系统采集陕西镇巴-重庆城口锰矿富集区典型锰矿床容矿岩石样品,采用元素地球化学方法研究该区域锰矿沉积环境和成矿作用。微量元素地球化学指标Th/U、Ni/Co、Ce/La、V/Sc、Cd、Mo分析显示:震旦系陡山沱期,自北西陕西镇巴至南东重庆城口沉积环境总体具有从氧化向还原变化的趋势。元素和氧化物富集效应的构造环境分析显示:镇巴至城口一带为大陆边缘向深海洋盆过渡带,其中镇巴地区为浅海或海陆过渡带,受气候及海平面升降影响明显,环境条件易发生变化,形成的锰矿物种类较多,并且多为氧化条件下形成;城口地区沉积水位较深,属于半深海至深海过渡带,沉积环境受海平面升降、气候、物源影响小,沉积环境稳定,形成的锰矿物较为单一,主要为菱锰矿。

The samples of ore bearing rocks of the typical manganese ore deposits have been collected from the metallogenic belt of Zhenba,Shanxi to Chengkou,Chongqing.The method of element geochemistry is taken to study the sedimentary environment and mineralization.Based on the analysis of the element geochemistry index of Th/U,Ni/Co,Ce/La,V/Sc,Cd and Mo,it can be concluded that the sedimentary environment changes from oxidation in Zhenba region to reduction in Chengkou region in the Doushantuo Stage of Sinian Period.In the tectonic environment,the area of Zhenba to Chengkou belongs to the continental margin and deep ocean.The Zhenba area is shallow sea or land sea transition zone,influenced easily by the climate and sea-level change,where much of manganese minerals were formed under the oxidation condition.On the other hand,Chengkou is in the semi-deep sea to deep sea region,which have stable sedimentary environment,and form rhodochrosite.