桂西荣华锰矿床地球化学特征与成因

Geochemical Characteristics and Metallogenesis of the Ronghua Manganese Deposit in Western Guangxi,China

为探讨桂西荣华锰矿床成因和成矿物理化学环境等问题,对其主(微)量元素特征进行了研究。结果显示,岩石不同元素的地球化学特征表明氧化矿石和地层沉积物质主要为陆源,Mn主要来自陆地。研究认为,矿区在中三叠世早期右江海盆自东向西萎缩过程中,沉积环境浅水环境转入深水环境,由氧化环境转换为还原环境,在氧化还原界面及其附近经过水成作用形成碳酸锰初步富集,表层风化临滤作用导致Mn元素再次富集成矿。

Inorder to discuss the metallogenesis and ore-forming physico-chemical conditions of the Ronghua manganese deposit in Western Guangxi,major and trace elements of ores and wallrocks of the deposit have been analyzed for comparisonal study in this paper. It is shown that sedimentary wallrocks and oxide ores of the deposit are mainly sourced from an ancient continent. Comparing to sedimentary wallrocks. oxide ores are rich in K,Rb,Th and REE,bu depleted in Sr,Ba,Nb,Ta,P and Ti elements,with similar characteristics of REE and other trace elements. The manganese which was mainly sourced from an acient continent was preliminary enriched in form of manganese carbonate deposited in the transition zone from shallow water to deep water（ from oxidation to reduce environment） in the Youjiang Basin during its shrinking process in Middle Triassic. The manganese was further enriched in oxide ores of the Ronghua manganese deposit due to the weathering and leaching of the manganese carbonate in Middle Triassic sedimentary rocks.