| The Greater Xing?an Mountains metallogenic belt is one of the most important metallogenic belt in northern China.Kaoshantun area of Horqin Right Front Banner in Inner Mongolia is located in middle area of the Greater Xing?an Mountains.The tectonic position is located at the intersection of Erlianhaote-Zhalantun deep-large fracture and the NNE-stretching main ridge in the supper imposed,composite and transformed area,where the Mesozoic NNE-stretching tectonic domain of the global Circum-Pacific belt strongly overprints the Paleozoic E-W-stretching tectonic domain of the Paleo-Asian Ocean.In the area,the volcano-magmatic activitites are frequently and fracture developed intensely which are advantageous to mineralization.The developed of Kaoshantun silver-lead polymetallic deposit in Inner Mongolia provided strong support to the regional metallogenic theory.This paper based on the project of the group.On the basis of plate tectonics theory,systematic use modern mineral deposit,geochemistry geophysics and precision analytical test methods,comprehensive research the deposit geological characteristics and ore control factors,discuss the ore-forming materials.We established the prospecting criteria of Kaoshantun ore area,and preliminary made metallogenic prognosis on this basis.We have achieved the following understanding and results.1.Ascertained the main ore-bearing strata of Kaoshantun ore area is tectonic altered rock,and determined the alteration types.They are existing on the stratigraphic contact belt between upper Jurassic Mantouerbo group strata and early cretaceous moyite.The wall rock alteration mainly is low to moderate temperature hydrothermal type.Kaoshantun ore area mainly developed quartzitificatio,chloritization,sericitization pyritization,clayization,limonitization,epidotization.2.Redefined the ore-controlling structure,and found that ore bodies mainly developed at the structural altered zones that are controlled by the NS-SE stretching fracture.The shape of ore bodies are long vein type,and irregular lenticular.Ore bodies mainly spread in the NNW-SW eastern direction,which are consistent with structural altered zones and strictly controlled by the fractures.At present,ore area altogether discovered three mineralized alteration zones,four silver-lead ore bodies and three silver lead(zinc)mineralized ore bodies.There are various types of ore.The main ore structures are block structure,infiltration structure,fine vein structure and so on.The main ore texture are metasomatic dissolution structure,semi-autochthonous granular structure,structure and so on.Ore minerals are mainly galena,cerussite,massicot,pyrite(lignite)and so on.The gangue minerals include quartz,sericite,chlorite,epiphyllite,etc.3.According to ore type,ore main structure,and wall rock alteration characteristics,the ore-forming stages of deposit and metallogenic stage has carried on the preliminary classification.4.Based on the comprehensive study on the geological characteristics of mineralized bodies and various aspects,it is preliminarily believed that the upper Jurassic Mantouebo formation provides main material source for the silver-lead polymetallic deposit in the Kaoshantun mining area.The fault structure provides a channel for the transport of mineral hydrothermal fluid and a place for the formation of ore body and controlling the location,shape and scale of the deposit's output;5.Through the comprehensive analysis of metallogenic geological information,establishing the most favorable prospecting criteria: NW-NNE fault-moyite-upper Jurassic Mantouerbo group strata,three-dimensional ore-controlling factors is a necessary condition of mineralized bodies formed in this area.Silication,sericitization,pyrite mineralization and lignite alteration are closly related to mineralized bodies.The area which geochemical anomaly of silver,lead and zinc in geochemical exploration is in good condition,with high intensity,high value superposition low resistivity area,high charging rate anomaly have the good metallogenic conditions and prospecting potential.Comprehensive consideration geological characteristics,we preliminary think this ore deposit is beginning with the long-term volcano-magmatic activities of Yanshanian period,forming mass of hydrothermal fluid,along with the fracture structures under the thermo-motive,metasomatisming wall rocks,extracting metallogenic materials,forming ore-bearing hydrothermal,and concentrating ore-forming in the favorable tectonic space. |
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