Discovery of the intrusive rocks hydrothermal altered clay-type lithium mineralization in southern Anhui Province and its geological significance
The clay-type lithium(Li)deposit is an important emerging lithium resource in the world because of their large scale,thickness and stable distribution.Three types of clay-type lithium deposits have been discovered in the world,including the volcanic clay-type lithium deposit formed by leaching extraction and alteration,the carbonate clay-type lithium deposit formed by weathering and sedimentation,and the kaolin weathering crust type lithium deposit formed from the granite type lithium by supergene weathering.The clay-type lithium mineralization discovered in the Jingde intrusion in southern Anhui Province is significantly different from the existing clay-type lithium deposits in terms of tectonic setting,orebody characteristics,host rocks,mineral assemblage,source of lithium,ore minerals and mineralization processes.It is a new type of lithium mineralization,temporarily called"intrusion rocks hydrothermal altered clay-type lithium mineralization".The main metallogenic characteristics include the following:(1)Lithium mineralization is later than the intruding of intermediate-acid rocks,and the ore bodies occur in the fracture zone and hosted by the intermediate-acid rocks;(2)The mineral assemblage consists of quartz,kaolinite,illite,fluorite,etc.,which is formed by hydrothermal metasomatism or direct precipitation from ore fluids;(3)Lithium occurs mainly in kaolinite and illite;(4)Lithium mainly comes from Li-F-rich ore fluids,which is most possibly released from magmatic differentiation(?);and(5)Hydrothermal-rock reaction between Li-F-rich ore fluid and intrusive rocks results in the formation of clay minerals(kaolinite,illite,etc.)replacing feldspar,hornblende and other changeable minerals,and the precipitation of quartz and fluorite veins;Meanwhile the lithium is hosted by the clay minerals.The new type of"intrusive rocks hydrothermal altered clay-type lithium mineralization"is essentially a new lithium mineralization process.The proposal of this type lithium mineralization extends the search for clay-type lithium resources from the lacustrine sedimentary distribution area of caldera(prospecting for volcanic clay-type lithium deposits),the distribution area of paleo-carbonate weathering and sedimentary interface(prospecting for carbonate clay-type lithium deposits),and the granite distribution area with albitization and muscovitization(prospecting for kaolin weathering crust type lithium deposits and related primary granite-type lithium deposits)to the distribution area of intermediate-acid intrusive rocks which may not host granite-type lithium deposits.This marks a significant expansion in lithium prospecting concepts.
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