Metallogenic System Of Copper-Lead-Zinc-Cobalt Polymetallic Deposits,Northeastern Hu'nan Province,South China

The area of northeastern Hu'nan province?NHP?,located in the multiple cracking and collision region of the Yangtze plate and the Cathaysia block,is a favorable metallogenic potential area and important mineral resources prospecting target of Cu,Pb,Zn,Co,et al.There is well ore-forming geological background,as the en echelon basin-mountain tectonic framework controlled by the large NNE and NE strike-slip fault system,and so many stakes of the strong acidic magma activities.However,the study of reginal mineralization of these Cu-Pb-Zn-Co polymetallic deposits is still relatively weak,and the scientific problems such as whether the Cu-Pb-Zn-Co polymetallic mineralization is an unified metallogenic system are still unknown,which needs to be solved.Guided by the regional metallogeny,based on the project of“geological and mineral survey in Northeastern Hu'nan province-Eastern Hubei province”from the China Geological Survey,the thesis focused on the mineralization of Cu-Pb-Zn-Co polymetallic deposits in NHP,selected the Qibaoshan Cu-polymetallic deposit,the Jingchong Cu-Co-Pb-Zn polymetallic deposit,the Taolin and Lishan Pb-Zn-Cu polymetallic deposit as the object,researched ore deposit geology characteristic,diagenetic and metallogenic epoch,analysised metallogenic material source and ore-forming fluid properties,discussed mineralization distinction,summarized the regional metallogeny,metallogenic regularity and metallogenic model,and constructed the metallogenic system,put forward suggestions for the further prospecting.Main achievements obtained are as following:?1?It is suggested that the Cu-Pb-Zn-Co polymetallic deposits is a magmatic hydrothermal metallogenic system related to magmatic intrusion in Yanshanian in NHP,under the background of the Pacific plate subduction,from SE to NW.The system can be divided furtherly into porphyry-skarn-hydrothermal vein type Cu polymetallic metallogenic subsystem,magmatic-hydrothermal filling-metasomatic Cu-Co-Pb-Zn polymetallic metallogenic subsystem,and magmatic-hydrothermal filling type Pb-Zn-Cu polymetallic metallogenic subsystem.The genetic types of these Cu-Pb-Zn-Co polymetallic deposits can be divided into the porphyry-skarn-hydrothermal vein type Cu polymetallic deposit,the magmatic-hydrothermal vein type Cu-Co-Pb-Zn polymetallic deposit,and the hydrothermal vein type Pb-Zn-Cu polymetallic deposit.The Yanshanian regional metallogenic model of Cu-Pb-Zn-Co polymetallic metal in NHP is summarized and refined.?2?It is determined that the magmatic rocks related to the Cu-Pb-Zn-Co polymetallic deposits of the metallogenic system intrude in the two periods of 153-148 Ma and 138-132Ma.There were there Cu-Pb-Zn-Co metallogenic events in NHP,which are the Cu-polymetallic metallogenic event during the late Jurassic?153 Ma±?,the Cu-Co-Pb-Zn polymetallic mineralization during the early Cretaceous?135-128 Ma±?,and the Pb-Zn-Cu polymetallic metallogenic event during the late Cretaceous?88 Ma±?.?3?From SE to NW,the diagenetic age of ore magma in the system of the NHP become from old to young,the same is generally true in the metallogenic epoch,overall.The mainly ore-forming elements are changed from Cu to Pb-Zn.The key control factors of mineralization is changed from the contact zone structure between the intermediate-acid magmatic rocks and the lively carbonate rocks,gradually shift to the coupling process between the intermediate-acid magmatic rocks and the massive fault activity,and the superposition activation of post-magmatic faults became the main controlling factor,furthermore.?4?It is proposed that the metallogenic materials of the Cu-Pb-Zn-Co polymetallic deposits,in this metallogenic system,are mainly from magmatic rocks,but maybe mixed by the materials of upper crust in a small but different proportion in different deposits in NHP.Among of them,the most likely source of metallogenic material in the Qibaoshan Cu-polymetallic ore is the typical magma source.An amount of crustal material was mixed into the Jingchong,Taolin,and Lishan polymetallic deposits.Moreover,the mixing proportion of Jingchong deposit is relatively higher,while the Taolin and Lishan deposits are lower.?5?The ore-forming fluids of the Cu-Pb-Zn-Co polymetallic deposits of NHP,in the metallogenic system,can be divided into 3 types:the first is the magmatic hydrotherm NaCl-KCl-H₂O system with medium-high temperature,medium-low salinity and low density,the second is the magmatic hydrothermel NaCl-Na₂SO₄-H₂O system with medium temperature,medium-low salinity and low density,and the third is the magmatic hydrothermel mixed with meteoric water NaCl-Na₂SO₄-CaCl₂-H₂O system with medium-low temperature,medium-low salinity and low density.