The Characteristics And Prospecting Direction Of Cu-mo Mineralization In The Sankuanggou Area, Nenjiang County, Heilongjiang Province

The Sankuanggou area,Nenjiang county,Heilongjiang province,located in the eastern part of the Xingmeng orogenic belt,west of the boundary fault between the xing'an block and the Songnen block?Hegenshan-Heihe fault zone?,is occurred in the northwestern part of the Duobaoshan-Sankuangou metallogenic belt.In addition to the Sankuanggou skarn-type Fe-Cu deposit,recent prospecting work has found porphyry molybdenum mineralization around the areas.This type of mineralization is produced in granodiorite.Based on the mineral assemblages and cross-cutting relationships of ore veins,the ore-forming process were divided into three stages:quartz–pyrite?stage I?,quartz-pyrite-molybdenite±chalcopyrite?stage II?,III pyrite-zincite-quartz?stage III?.The fluids of stage I and II were composed of gas-rich,NaCl-containing and gas-liquid type fluid inclusions with homogenization temperatures and salinities of 170.4to 337.8?and 31.26 to 41.01wt%NaCl eqv.,respectively.The fluids of stage III was composed of gas-liquid type fluid inclusions with homogenization temperatures and salinities of 122.3 to 213.4?and 2.06 to 7.99 wt%NaCl eqv.,respectively.The initial ore-forming fluids of the Sankuanggou area had Mid-high temperature,high salinity,and belonged to a NaCl–H₂O system.The fluids gradually evolved to low temperature,low salinity,and belonged to a NaCl–H2O system.Studies of the hydrogen and oxygen isotope of quartz(?D=-90.2‰^-96.8‰;?¹⁸O=-2.1‰⁴.0‰)show that the ore-forming fluids gradually evolved from magmatic water to meteoric water.Sulfur and lead isotopic studies show that the ore-forming materials mainly derived from the mantle and crustal.The Cu-Mo mineralization in the area is produced in the granodiorite body,which has the characteristics of porphyry mineralization.The zircon U-Pb geochronology results show that the ages of granodiorite and diorite formation in the area are 167.1±1.6Ma and165.9±1.5Ma,respectively.Therefore,it is believed that the main metallogenic occured in the Middle Jurassic.Granodiorite rock belong to the characteristics of high-K calc-alkaline series and weakly peraluminous rocks.It is enriched in LILEs and LREEs and depleted in HFSEs and HREEs.The porphyry Cu-Mo mineralization are controlled by annular fault and Middle Jurassic granitic magmatism.Mineralization,which is necessary ore-forming geological condition of this area.Potassiumization and silicification;middle Jurassic acid intrusive rock;NW and ring structure,the Mo-W-Ag-Au-Bi-Cu prospecting element combination,the high magnetic gradient zone,and the low-resistance and high-polarization anomaly are the signs of direct prospecting in this area.Combined with the geological,geophysical and geochemical characteristics of the Sankuangou area,the next prospecting direction of the area is defined.Four prospecting target areas were selected by the comprehensive forecast of MRAS mineral resources evaluation system.