Geological Characteristics And Prospecting Direction Of Songjianghe Gold Deposit In Dunhua City,Jilin Province

Songjianghe gold deposit is located in the secondary fault zone of Qingchaguan-Baishuitan deep fault zone that is situated in the eastern part of the northern margin of North China Craton and Central Asia Orogenic Belt contact zone,and in the middle part of Jiapigou-Songjianghe-Haigou metallogenic belt.On the basis of previous exploration and research work,this paper guided by the theory of integrated information regarding mineral prediction,beginningwith the study of geological characteristics of deposits,studying the genesis of deposits,analyzing the geological conditions of mineralization,summarizing the geological,geochemical and geophysical prospecting indicators,and evaluating the prospecting potential of the study area,in order to indicate the following prospecting work and deployment direction.The Songjianghe gold deposit is hosted in the metamorphic strata of the Seluohe Group(Pt₂s¹³).The main mineralization type is the altered rock type in the fractured zone,followed by the sulfide-bearing quartz vein type.The main metal minerals in the ore are pyrite,chalcopyrite,and ilmenite,followed by sphalerite,galena,and magnetite.Gangue mineralsaremainlyquartz,calcite,andmica.Theoreshowsas automorphic-semi-automorphic granular structure,metasomatic structure,disseminated structure,and banded structure.The wall rock alteration mainly includes silicification,chloritization,carbonation,sericitization,and so on.Metallogenesis can be divided into four stages:quartz stage,quartz-pyrite stage,gold-pyrite-polymetallic sulfide stage and quartz-carbonate stage.Gold-pyrite-polymetallic sulfide stage is the main metallogenic stage.Compared withtypical deposits,the deposit is a mesothermal hydrothermal gold deposit.The data of 1:10 000 soil geochemical survey in the mining area were reprocessed.The results show that Au,Pb,Mo and other elements in the study area display high background field characteristics,while Au and Mo elements show strong variation characteristics,suggesting that Au and Mo are the main metallogenic elements in the mining area.Cluster analysis and factor analysis show that the metallogenic elements can be classified into four elements:AsSbZnPb,CuAgPbZn,Au?-Ag?,Mo,which reflects the multi-stage metallogenic characteristics of this area.According to the content characteristics of ore-forming elements,64 anomalies of Au,Pb,and Mo are delineated,and 7 anomalies of ore-forming elements combination are found.The known ore bodies occur in HT-7 anomalies,indicating that they are ore-forming anomalies.There are many kinds of ore-forming elements,good anomalies combination,and obvious concentration centers in no ore-formingcombination anomalies of HT-2 and HT-5,indicating that they have good prospecting potential.Analytical processing of polarization,continuation and derivation of high magnetic survey data shows that high magnetic anomalies in the mining area are characterized by gentle positive anomaly field,positive and negative alternating anomaly field,and gentle negative anomaly field,and 19 high magnetic anomaly areas?11 positive anomalies and 8negative anomalies?are delineated.According to the results of the horizontal first derivative calculation,the linear structures with different heights and directions?structural planes with different physical properties?are extracted.According to the vertical second derivative,geological bodies of different heights?annular structures?are interpreted.The known ore bodies are mainly controlled by the intersection of NW-trending structures and annular structures.The study shows that NW-trending structures,NE-trending structures and their intersection sites,and the intersection of NW-trending structures and annular structures are important prospecting indicators.According to the relationship between Songjianghe gold deposit and lithology of host stratum,fault structure,and magmatism,the metallogenic geological conditions are analyzed.According to the statistical characteristics of ore-forming elements content in different lithologies,it is considered that the Songjianghe gold deposit is mainly derived from the strata of the Seluohe Group,and the near SN and NW trending structures are the main ore-controlling structures.The early Yanshanian granitic magmatism provides the thermal power,ore-forming hydrothermal solution and some ore-forming materials for the formation of the deposit,which constitute the main geological conditions of the Songjianghe gold deposit.The geological,geophysical,and geochemical prospecting indicators of Songjianghe gold deposit have been determined.Silicification and sericitization alteration are geological indicators for gold prospecting.The anomalies of Au,Ag,Cu,Pb,Zn,As,Mo,Sb,and the combination anomalies of HT-2,HT-5,and HT-2 are geochemical indicators for prospecting.In the transitional area of high magnetic positive and negative anomalies,high magnetic interpretation of NW,NE,SN structures and their intersections,and the intersection of NW structures and annular structures are high magnetic prospecting indicators.According to the favorable degree of metallogenic conditions and the development of wall rock alteration,high magnetic anomaly and high magnetic interpretation line-annular structure,soil element anomaly,and combination anomaly,the prospecting prediction is studied,three prospecting prediction areas?one first-level prediction area and two second-level prediction area?are delineated,and a prospecting target area is selected,which point out the direction for further prospecting.