Geological Characteristics And Peripheral Predictions Of Erdaohe Lead-Zinc-Silver Deposit In ZhaLanTun Area, Inner Mongolia

Erdaohe lead-zinc-silver deposit of ZhaLanTun area in Inner Mongonia located in themiddle of Daxinganling metallogenic belt, which is an important district of lead-zinc-silverpolymetallic ore in Daxinganling region. On the basis of previous data collettion and fieldgeological investigation and research, the author conducted the study of rock geochemistry,fluid inclusion testing analysis, and comprehensively analysed the geological characteristicsof Erdaohe lead-zinc-silver deposit, generally ascertained the genesis and metallogenicmechanism of the deposit, proposed the metallogenic geological conditions and prospetingmarks, also established a typical deposit prospecting model of general informations. What’smore, under the guide of prospecting model, we used the metallogenic predition theory andcombined with the informations of mining periphery, aiming to predict the concealedorebodies of Hekoulinchang distict, also verified them with the implementation project.The study of deposit geology shows that the lead-zinc-silver orebodies of Erdaohe occursin the Luohe Formation of Ordovician and Manketouebo Formation of Jurassic, strictlycontrolled by faults, and its orebodies are mainly of vein type. The metallic minerals of thedeposit mainly consist of sphaletite, galena, pyrite and minor chalcopyrite, magnetite,pyrrhorite and so on. The wall rock alterations from orebodies to wall rock exists evidentzonation, which varies from silicified to beresitization, to sericite and carbonate, to chloriteand epidotization. The study of fluid inclusions testing shows that the main mineralizationtemperature of Erdaohe lead-zinc-silver deposit ranges from200℃to280℃, and theore-forming depth is0.82～1.46km, it reflects the epithermal mineralization characteristics.The study of H-O isotopes shows that the deposit has a deep characteristic of hydrothermalsource, the ore-forming fluids are mainly magmatic water, also contain a small amount of atmospheric water. It belongs to hypabyssal hydrothermal vein type deposit.The study of ore-forming geological conditions indicates that the lead-zinc-silvermineralization is closely associated with the regional faults structure. Specifically, the NEdeep fault of Habuqilinchang-Yiqihanlinchang, together with the NE and NW trendingsecondary faults controlled the spatial distribution of the deposits. The relationship ofvolcano-volcanic magmatism and mineralization showed that these lead-zinc-silver depositswere formed at the late period of the magmatism, magmatic activities of volcanic-volcanicprovided metallogenic material and heat sources, the assemblage of volcanic-subvolcanic rockclosely associated with mineralization is mainly rhyolitic tuff-granite porphyry-(quartz)diorite porphyry. Besides shallow metamorphic rocks are relatively close to mineralization,the combination of metamorphic rock is mainly metamorphic fine sandstore-argilliteslate-dolomitic limestone.The integrated prospecting information of Erdaohe lead-zinc-silver deposit peripheryindicates that the main strate of Hekoulinchang distict are metamorphic fine sandstones orargillite slates in Luohe Formation and acidic volcanic rocks in Manketouebozu Formation, itexsits the contact zone between acidic intrusive with tuff, NE trending faults and rockalterations are intense, so it has the similar metallogenic geological conditions to Erdaohelead-zinc-silver deposit. The study of geophysical informations show Hekoulinchang disticthas apparent precision magnetic and induced polarization abnomalies, these importantgeophysical abnomal positions are that the apparent resistivity is less than800·m and thepolarization is more than5.0%. The lead-zinc-silver abnomalities of soil geochemical surveyare obvious, which has a degree of coincide with the geophysical abnomal zones, so it is thebeneficial location to prospect the lead-zinc-silver polymetallic orebodies.Under the guidance of metallogenic predication theory, as well as compared to theErdaohe lead-zinc-silver prospeting model, we used the comprehensive prospecting methodsof geological preliminary investigation, high precision magnetic survey, induced polarizationintermediate gradient survey and soil geochemical survey to predict the orebodies inHekoulinchang distict. The total area included four comprehensive targets, through the targetoptimization analysis, three gradeⅠ and one gradeⅡ integrated prediction targets were totallydelineated. Moreover, we carried out trenching and drilling works to verfy the mineralization favourable areas within ZHBQ-4, the results showed that two lead-zinc-silver orebodies werecontrolled. TheⅡ orebody occurs in metamorphic fine sandstone and argillite slate of theLuohe Formation, the wall rock alteration is siglicication and epidotization, the average gradeof lead-zinc-silver respectively is1.16percent,1.47percent, and49.13multiply10-6. Theestimate of mineral resource or reserve shows that there are7447.2tons of lead,9437.4tonsof zinc and31.5tons of silver in Hekoulinchang region.The research amply demonstrated that application of a typical deposit prospecting modeland integrated information metallogenic prediction methods are feasible and effective in theHekoulinchang distict, also it is beneficial to specify the direction for mineral exploration inthe Erdaohe lead-zinc-silver deposit periphery.