The Cu Mineralization Characteristics And Prospecting Direction In The Heibaoshan Area,Nenjiang County,Heilongjiang Province

The Heibaoshan area in Nenjiang County,Heilongjiang Province is located in the northeast section of Greatxing'an Range,in the Duobaoshan island arc zone of Xing'an block,and in the east of Hegenshan-Heihe deep fault,which is mesothermal hydrothermal vein type copper mineralization.The outcropping strata are mainly Ordovician Duobaoshan formation(O₂d),and the structures are mainly NE and NW trending,with less magmatic rocks exposed in the area.Copper mineralization occurs mainly in the South East of the area,and occurs in granodiorite in veinlet,disseminated and veinlet disseminated forms;Wall rock alteration includes silicification,sericitization,chloritization and kaolinization.According to the mineral assemblage and the relationship between ore veins,the mineralization can be divided into I.quartz+pyrite;II.quartz+chalcopyrite+pyrite+sphalerite;?.Calcite+poor sulfide.Among them,stage II is the main stage of copper mineralization.Petrography and microthermometry of fluid inclusions show that gas-liquid two-phase fluid inclusions(VL type)are developed in quartz grains of stage I and II of copper mineralization in Heibaoshan area,and the ore-forming fluid is Na Cl-H₂O hydrothermal system with medium low temperature(180.6?352.3?)and low salinity(3.7?8.1wt.%Na Cleqv.);In stage III,gas-liquid two-phase fluid inclusions(VL type)are mainly developed in quartz grains.The ore-forming fluid is Na Cl-H₂O hydrothermal system with low temperature(141.6?207.3?)and low salinity(1.0?5.8 wt.%Na Cleqv.).Hydrogen and oxygen isotope analysis data shows that the early stage of the ore-forming fluid(?D:-98.7‰?-95.6‰;?¹⁸O:-0.6‰?0.6‰)in the Heibaoshan area may be a mixture of magmatic water and atmospheric precipitation,and the late fluid(?D:-115.4‰;?¹⁸O:-6.9‰)The main source of atmospheric precipitation.The LA-ICP-MS zircon U-Pb dating test result of the granodiorite is 483±3 Ma.The petrogeochemical analysis of the granodiorite shows that it has a weak peraluminate.High potassium-calcium alkaline rock series(A/CNK is 1.09?1.11;A/NK is 1.48?1.57;Ritman index is(?)2.18?2.55;Si O₂content is 64.57%?65.68%;K₂O content is 2.82%?3.82%),light rare earth enrichment,heavy rare earth depletion and enrichment of large ion lithophile elements and elemental chemically active incompatible elements,relatively depleted high field strength elements(mean value of?REE is 58.68×10^-6;The value of?Eu is 1.04?1.19).The above research results show that the copper mineralization in Heibaoshan area was formed in the subduction environment of paleo Pacific plate to Erguna Xing'an block.Copper mineralization in the Heibaoshan area is controlled by the north-north-west trending structure,which is the main metallogenic geological condition in this area.Silicification and sericitization;granodiorite intrusions closely related to mineralization and characteristics of geophysical and geochemical anomalies(Au,Ag,As,Sb,Cu,Pb,Zn,Mo and other elemental soil combination anomalies,high magnetic gradients and low The abnormality of resistance to advancedization)is the sign of prospecting in this area.The MRAS system is used to predict mineral resources,and 5 metallogenic target areas are circled to provide directions for the next prospecting work in the Heibaoshan area.