Geological Characteristics and Mineralization Age of Yezhutang Gold Deposit in Micangshan Area,the Northern Margin of Yangtze Block,China
Intense plate interactions and deep magmatic activities occur in Micangshan area,the northern margin of Yangtze Block during Early Neoproterozoic.However,the extent of contemporaneous mineralization in the region remains unclear.Yezhutang gold deposit is a newly discovered medium-sized gold deposit in Micangshan area in recent years.Based on the detailed investigation of deposit geological characteristics,in-situ Rb-Sr dating on hydrothermal muscovite that formed in the mineralization period was carried out to determine its metallogenic age,and its tectonic setting was discussed to provide support for studying the deposit genesis and regional gold exploration.Yezhutang gold ore bodies are mainly hosted in the metamorphic sedimentary rocks of Mesoproterozoic Mawozi Formation,and controlled by secondary fault zones of the NEE-trending Zhujiaba Fault.The gold ore bodies occur in vein and lens-like forms,with marble,quartzite,and phyllite as the main wall rocks.Three gold mineralization alteration zones can be identified in the ore district,with silicification and muscovitization closely related to gold mineralization.The gold ores in Yezhutang deposit can be classified into three types based on mineral assemblages,including pyrite ore,pyrite-limonite ore,and limonite ore.The ore minerals are mainly pyrite,limonite,and native gold,while the gangue minerals are primarily quartz,muscovite,and sericite.The gold mineralization process can be divided into two periods,including the hydrothermal period and the supergene period.The hydrothermal period can be further divided into the quartz-pyrite stage and the quartz-muscovite-sulfide stage(the main mineralization stage).The isochron age of in-situ Rb-Sr dating on hydrothermal muscovite is(850±20)Ma,indicating that the gold mineralization occurs in Early Neoproterozoic.It is consistent with Early Neoproterozoic magmatic activity in Micangshan area,suggesting that the deposit forms in the subduction setting in the northern margin of Yangtze Block during this time.Comparison of the mineralization age and tectonic setting of the gold deposits suggests that there is significant potential for gold mineralization related to the convergence and breakup of Rodinia supercontinent at the periphery margins of Yangtze Block.
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