河南省桐柏银洞岭银矿床地质地球化学特征

银洞岭银矿床属变质碎屑岩型银(金)矿床, 其成矿元素含量变化与歪头山岩组地层层序、岩石类型密切相关, 歪头山岩组下部变粒岩、云母石英片岩Ag含量相对较高, 成为银矿体的直接赋矿围岩;蚀变作用导致成矿元素显著带入, 而对稀土元素的迁移影响不大;成矿热液的运移以渗流作用为主、渗透作用为辅;通过对银洞岭银矿床地质地球化学评价标志的建立, 为该类型矿床的普查评价起到借鉴作用。

GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF THE YINDONGLING SILVER DEPOSIT,TONGBAI COUNTY, HENAN PROVINCE

The Yindongling silver deposit is another important discovery in the Weishancheng metallogenic belt after the discovery of the Poshan silver deposit and the Yindongpo gold deposit.Its discovery is also a new breakthrough in prospecting for metaclastic type silver(gold) deposits in recent years.The summarization of the ore-forming geological conditions and geochemical characteristics of the Yindongling silver deposit is of great significance.Geochemical characteristics of the Yindongling silver deposit show that the variation of ore-forming elements is closely related to stratigraphic sequences and rock types of Waitoushan Formation.Ore-forming elements are obviously different in different strata and rock types.Au and Ag are relatively high in carbonaceous-sericite-quartz schist and leptite of the middle-upper part of Waitoushan Formation,and in leptite and mica-quartz schist of the lower part of Waitoushan Formation,which are direct wall rocks of Ag-Au orebodies.Alteration leads to obvious entrance of ore-forming elements but exerts no remarkable influence on the transportation of rare earth elements.Based on horizontal and vertical zoning,the author considers that the transportation of ore-forming hydrothermal solution is mainly in the form of percolation,and subordinately in the form of infiltration.According to geological and geochemical characteristics and element ratios at different elevations,the author has established geochemical assessment criteria,which are of reference value in the prospecting and evaluation of ore deposits in this area.