Study on the geological conditions of metallogenesis of the Shazi large-scale anatase deposit in Qinglong County, Guizhou Province  

作　　者：ZHANG Min NIE Aiguo XIE Fei ZHANG Zhuru 

机构地区：[1]Guizhou Institute of Technology [2]Guizhou University

出　　处：《Chinese Journal Of Geochemistry》2014年第4期450-458,共9页中国地球化学学报

摘　　要：The Shazi large-scale anatase deposit in Qinglong County, Guizhou Province, has been discovered recently and now is under exploration. Investigations show that the orebodies mostly occur at the top of the karst unconformity of the Middle Permian Maokou Formation strata and at the bottom of the Emeishan basalt. And the following three prerequisites should be satisfied for the formation of the deposit: 1) there must be the material source of anatase; 2) there must be weekly alkaline media and low-tempeature and low-pressure conditions; 3) there was no high-temperature and high-pressure environment subsequently for the transformation of anatase into rutile. In the Emeishan basalt of western Guizhou, the element Ti mostly entered the silicon-oxygen tetrahedra of picrite in heterovalent isomorphism(Ti4++Al3+→Mg2++Si4+). When volcanic ejecta resultant from strong eruption of the Emeishan basalt magma fell into water, picrite was usually dissociated to chlorite. Thus, the element Ti4+ in the picrite could be released from the silicon-oxygen tetrahedraa of picrite into water, and conbined with oxygen in the water to form Ti O2. This paper has proved that this deposit, enriched in anatase, discovered recently at Shazi, Qinglong Country, Guizhou Province, is a residual-deluvial-type deposit. Its genesis can be explained as follows. Volcanic clastics formed at the early stage of strong eruption of the Emeishan basalt magma were chemically deposited to form anatase in the low-temperature, low-pressure and weekly alkaline waters in the karst depressions at the top of the Maokou Formation(limestone) strata. The anatase was then dissociated owing to weathering and leaching during the Quaternary and the anatase was further enriched to form the residual-deluvial-type anatase ore deposit.The Shazi large-scale anatase deposit in Qinglong County, Guizhou Province, has been discovered recently and now is under exploration. Investigations show that the orebodies mostly occur at the top of the karst unconformity of the Middle Permian Maokou Formation strata and at the bottom of the Emeishan basalt. And the following three prerequisites should be satisfied for the formation of the deposit： 1） there must be the material source of anatase; 2） there must be weekly alkaline media and low-tempeature and low-pressure conditions; 3） there was no high-temperature and high-pressure environment subsequently for the transformation of anatase into rutile. In the Emeishan basalt of western Guizhou, the element Ti mostly entered the silicon-oxygen tetrahedra of picrite in heterovalent isomorphism （Ti4＋＋Al3＋→Mg2＋＋Si4＋）. When volcanic ejecta resultant from strong eruption of the Emeishan basalt magma fell into water, picrite was usually dissociated to chlorite. Thus, the element Ti4＋ in the picrite could be released from the silicon-oxygen tetrahedraa of picrite into water, and conbined with oxygen in the water to form TiO2. This paper has proved that this deposit, enriched in anatase, discovered recently at Shazi, Qinglong Country, Guizhou Province, is a residual-deluvial-type deposit. Its genesis can be explained as follows. Volcanic clastics formed at the early stage of strong eruption of the Emeishan basalt magma were chemically deposited to form anatase in the low-temperature, low-pressure and weekly alkaline waters in the karst depressions at the top of the Maokou Formation （limestone） strata. The anatase was then dissociated owing to weathering and leaching during the Quaternary and the anatase was further enriched to form the residual-deluvial-type anatase ore deposit.

关 键 词：矿床成矿 锐钛矿 贵州省 晴隆县 地质条件 峨眉山玄武岩 火山喷发物 硅氧四面体 

分 类 号：P618.47[天文地球—矿床学]