Geological Characteristics And Prospecting Indicators Of Bagabayan Ag-Pb Polymetallic Ore Deposit In Zhengxiangbaiqi,Inner Mongolia

Zhengxiangbaiqi,Inner Mongolia is located on the.late Paleozoic accretionary continental margin of the Xianghuaqi-Chifeng region,and is part of the north margin of North China Craton(NCC),and.Orogeny occurred many times,resulting in extensive faults and frequent magmatism.In this contribution,we systematically studied the geological characteristics of the Bagabayan Ag-Pb polymetallic ore area and the orebodies,and the relationship between the ore-controlling factors and the ore-forming geological conditions of the Ag-Pb polymetallic ore deposits.In addition,the prospecting indicators were summarized,and the comprehensive prospecting model was established.Three mineralization zones and six orebodies are distributed in the area,which are dominated by silver,lead,zinc mineralization and are controlled by the near east-west compressive and tensional faults.The ore-bearing wall rocks are the upper Jurassic manitu formation andesites and the late Jurassic quartz diorite porphyrites.The Ag-Pb-Zn ore bodies are 100-260 m long,3.61-5.42 m thick and 96-129 m in depth,with the average Ag,Pb and Zn grades of 67.89-76.43 g/ t,0.653-0.715%,and 0.954%,respectively.The ore-bearing wall rocks are mainly altered by epidotization and carbonatization.It is suggested that the Bagabayan Ag-Pb polymetallic deposit belongs to the hydrothermal-vein filled deposit related to Mesozoic volcanic hydrothermal solutions,and its metallogenic age may be the late Yanshanian.After comprehensive study,prospecting indicators of Ag-Pb polymetallic ore deposits are proposed as follows:(1)contact and neighbouring area of the Manitu Formation dacite volcanic in the upper Jurassic and intrusive rocks in the Cretaceous are the favorable metallogenic bodies;(2)the E-W trending fault struture in the regional is a favorable ore prospecting indicator;(3)the geochemical indicator is the mutual anomalies overlapping and superposition of the elements(e.g.,Au,Ag,Pb,Zn,As,Sb,Cd)along the fault;(4)the geophysical signs are the abnormal gradient zones of charge rate and resistivity rate,and the variation zone and distortion-deformation zone of contour gradient at the edge of magnetic anomaly.This study is of great significance for further exploration of regional Ag-Pb polymetallic ore deposits.