Geochemical Behavior of Manganese in Weathering Environments and Its Significance in Exploration

Under and climate conditions the chemical weathering of manganese ores is govermed by the fugacities of O2,CO2 and S2 in the atmosphere and soils.Manganese minerals exhibit solid phase transformations without migration of Fe and Mn.Under tropical and subtropical humid climate condi-tions low-valent Mn is instable and apt to be oxidized into high valency state.High-valent Mn miner-als are stable and easy to form secondary high-grade Mn ores.Secondary concentration is possible for Mn ores in carbonate formations,while those in clastic rocks tend to migrate and may be washed away.Such differences are the main obstacles in prospecting Mn ore deposits.     

锰在风化作用中的地球化学行为及其在找矿中的意义

干燥气候下,锰矿石的化学风化受大气和壤中O_2、CO_2、S_2逸度控制,锰矿物呈固相转变,不存在Mn、Fe元素迁移现象。热带、亚热带潮湿气候,低价锰矿物不稳定,地表易氧化成高价锰;高价锰矿物稳定,易形成次生富锰矿。碳酸盐建造中锰矿可次生富集,碎屑岩建造中锰矿易流失迁移。这种差异是锰矿找矿中的主要障碍。