Mineralization Alteration Zoning Model And Orebody Deep Extension Pattern Of Huangshaping Cu-Sn Polymetallic Deposit

The Huangshaping Cu-Sn polymetallic deposit is one of the typical representatives of the Cu-Sn Polymetallic ore complex metallogenic system in the compound position of Nanling and Qinhang metallogenic belt in southern Hunan?Taking the different levels typically Pierce the veins as examples,Based on the large-scale fine measurement of tunnel section and mineral geochemical analysis of mineral rock,The differences of surrounding rock alterations in different rock masses are compared,and the mineralization-alteration zoning rules and characteristic element combination groups in different zones are summarized.The spatial change rule of element combinations in this deposit is revealed,especially the mineralized elements and the change law of its ratio and its significance.Combined with the vertical changes of trace elements in different levels magnetite and fluorite,it is shown that there is a geochemical interface with abrupt changes in physical and chemical conditions near the-176m levels of the deposit.The mechanism of the mineralization-alteration zoning of this deposit was discussed,and the preliminary pattern of the mineralization-alteration spatial zoning model and the deepening of the ore body was constructed.The main achievements as follows:1)Through the large-scale fine measurement of tunnel section,there are differences between the quartz porphyry and granite porphyry rock alterations in terms of mineralization-alteration type and mineral combination.Focusing on surrounding rock alterations related to granite porphyry,From porphyry(internal zone)?contact zone?surrounding rock(outer zone)with Scheelite-molybdenite(pyrite)mineralized–silicified-sericitized granite porphyry zone(?)?Magnetization(scheelite-cassiterite)mineralized garnet skarn zone(?-1)?Scheelite–molybdenite-pyrrhotite mineralized garnet skarn zone(?-2)?Lead-Zinc mineralized crystalline limestone zone(?)?Strong calcitization limestone zone(?),The main mineral assemblages of corresponding zones is:Qtz+(Py+Ser)?Mag+Di+Wo+Ep+Chl+(Sh+Cst+Py+Grt)?Sh+Mo+Po+(Cst+Cp+Py)+(Sp+Gn)+Grt+Ves+Di+Hbl+Fl+Ep+Chl+(Qtz+Cal)?Gn+Sp+(Py)+Cal+Qtz?Cal+Qtz?2)Based on the research on the composition characteristics of main trace elements in different horizontal directions of the middle section,it shows that from the porphyry to the surrounding rock,the content of Si O₂ gradually decreases,while the content of Ca O gradually increases,the content of ^TFe₂O₃ first gradually increases and then decreases,while the content of Al₂O₃ and Mg O have the opposite trend;?REE in horizontal direction is roughly to reduce the trend,the delta Eu wane;Different in-band feature element groups:?characteristic element group for W,Mo,Nb,Y,?-1 characteristic element group for Fe,W,Sn,(Bi,Mo),Y,Nb,?-2icharacteristic element group for W,Sn,Bi,Mo,(Cu,Pb,Zn)Ba,Y,?characteristic element group for Pb,zinc,Ag,Sr,V,Ni,Cr,Ba,?characteristic element group for Sr,Ba,Ni.The research and analysis of mineral elements and characteristic minerals(magnetite and fluorite)in different levels show that the content of mineral elements in the middle section of-176m is higher than that in the middle sections of-136m and-256m.An obvious inflection point appeared in the middle of the-176m levels,indicating the existence of a geochemical interface of fluid mineralization near the middle of the-176m levels,which resulted in a sudden change in the physicochemical conditions of the ore-forming fluid,and a variety of ore-forming elements accumulated here.3)The mechanism of mineralization-alteration zoning is discussed in terms of fluid composition,temperature and salinity,acid-base,redox conditions,chemical reactions of altered minerals,and transport and enrichment of mineralized elements.The characteristics of the altered zoning in this area show the transformation process of the fluid from alkaline?acid?weak acid or weak base,oxidation?reduction,and the temperature and salinity of the fluid gradually decrease as the water-rock reaction proceeds.4)Based on the comprehensive analysis of the above contents,the deep extension pattern of the ore body is predicted,and the next fluid mineralization geochemical interface may be at-496m.This study has guiding significance for the study of the ore-forming mechanism and deep prospecting of similar deposits in the deposit and even within the area.