Geological Characteristics And Ore Genesis Of Copper-molybdenum Deposit In The Southern Huoluotai Area In The Greater Khingan Mountains

The copper-molybdenum deposit in the soutehern Huoluotai Area?,located on the iron,copper,gold,molybdenum and tungsten metallogenic zone?belt?,is one of the copper-molybdenum deposits with great metallogenic potential discovered in the northern section of the Greater Khingan Mountains.Based on the regional geology,characteristics of the deposit,the geochemical analysis and zircon U-Pb dating of dioritic porphyrite,mineral electron probe analysis,stable isotope study,and the fluid inclusion studies,discuss the eveolution of ore-forming fluid,the age of diagenesis and mineralization,the tectonic background and the genesis of ore deposit,to provide help for the study of regional similar ore deposits and the breakthrough of prospecting in the soutehern Huoluotai Area?.The main findings are as follows:The mining areas are easy to emerge in the interior,mainly the xinghua formation(Pt_2-3xh)and the quaternary holocene?Qh?in the middle and new proterozoic xinghua dukou group.The fault structures in the mining area are divided into nnw-trending and nne-trending groups,which are rock-controlling structures in the mining area.Intrusive rocks are developed in the mining area,including early-late Jurassic intrusive rocks and early cretaceous intrusive rocks,among which early cretaceous granodiorite porphyry is the main ore-bearing rock in the mining area.Vein rocks include diorite vein,diorite porphyry,granitic porphyry,etc.Vein rocks have a certain destructive effect on the ore body,but the effect is small.Vein rocks are superimposed with new mineralization and alteration.U-Pb of diorite porphyrite zircon is 140.6±1.8ma,which belongs to the early cretaceous.The source region of the diorite porphyrite is formed by the reaction of the fluid generated by the subduction plate dehydration with the mantle wedge during the rising process.The diagenetic and metallotectonic setting may be influenced by the post-orogenic extension of the mongolian-okhotsk tectonic domain and the post-subduction arc expansion of the Pacific plate.The ore body in the mining area is multi-layer spindle-shaped and wedge-shaped.The metallic minerals in the mining area include pyrite,chalcopyrite,molybdenite and the supergene metallic mineral limonite,etc.The non-metallic minerals include quartz,plagioclase,alkali feldspar,biotite,amphibole,etc.The ore structure includes automorphic-semi-automorphic granular structure,metasomatic etching structure,solid solution separation structure,etc.The ore structure is sparsely disseminated,netted vein,mass structure and so on.The mining area has typical surface alteration characteristics?from center to outside:kalification zones-huangfei-sericite zones-qingipanitization zone?.The metallic electron probe in the mining area shows the characteristics consistent with the hydrothermal origin deposit.Characteristics of fluid inclusion in mining area:Sub-containing mineral inclusions,CO₂-containing three-phase inclusions and gas-liquid two-phase inclusions?gas-rich phase and liquid-rich phase?are developed in the mining area.The early stage of mineralization is characterized by high-temperature and high-salinity fluids,and the main mineralization depth is 0.6³.7km.Hydrogen and oxygen isotopes show that the ore-forming fluid came from magmatic water and tectonic water,and atmospheric water was added.Carbon and oxygen isotopes show that calcite is related to magmatism and has deep source characteristics.The S isotope shows that the metallogenic material originates from deep crust and is related to deep magma.Molybdenite precipitation is related to fluid boiling and temperature reduction,while chalcopyrite and other metal sulfide precipitation is related to temperature reduction and atmospheric water addition.Through the analysis,this paper argues that holos?area south of copper molybdenum deposit The copper-molybdenum deposit in the soutehern Huoluotai Area?is a typical porphyry deposit.