| The Xiagalaiaoyi Pb-Zn deposit is in the northwest of Huzhong area in the northern section of the Great Xin'an Range,and its tectonic location is in the western section of the intersection between the southern edge of Ermur mountain uplift belt of Erguna block and the northern edge of the Great Xin'an Range fault depression volcanic rock belt.It is a medium-scale skarn type Pb-Zn deposit newly discovered in recent years,accompanied by Fe,Ag and Mo.The study area is in the Mesozoic Ag,Pb,Zn,Cu,Mo and Au metallogenic sub belt in Derbugan,with complex regional tectonic background.Since Paleozoic,it has experienced the evolution of Paleo Asian Ocean tectonic system and Circum Pacific tectonic system,as well as the superposition and transformation of Mongolia Okhotsk tectonic system,with good metallogenic conditions,and has higher research significance.Under the guidance of comprehensive information mineral prediction theory,this paper studies the metallogenic geological conditions and main ore-controlling factors of the deposit from the regional metallogenic geological background and geological characteristics of the Xiagalaiaoyi Pb-Zn deposit.The collected geophysical and geochemical data are reprocessed and interpreted to extract the geochemical and geophysical marker information of mineralization prediction.On this basis,we carried out the comprehensive information metallogenic prediction research,established the metallogenic prediction model,delineated the metallogenic prediction area,and pointed out the direction for further prospecting work.The Xiagalaiaoyi Pb-Zn deposit is a skarn type deposit dominated by Fe,Pb,Zn and Mo.The outcrops in the mining area are the Upper Proterozoic – lower Cambrian Wolegen group Jixiangou formation,the Early Cretaceous Guanghua formation and the Holocene Quaternary system.The intrusive rocks are mainly early Cambrian and early-middle jurassic granite.Faulted tectonic was well developed,and the NE and NW faults are the main ore-controlling structures.The ore body occurs in the contact zone between the intermediate-acid shallow intrusive rocks and the marble of Jixiaangou Formation and the skarn of nearby marble.LA-ICP-MS zircon U-Pb dating results show that the diagenetic ages of the intrusive rocks related to mineralization in the study area are concentrated in the Early to Middle Jurassic,among which the latest ages are169±2Ma and 166±2Ma for potassium feldspar granite,suggesting that the mineralization age of the Xiagalaiaoyi Pb-Zn deposit is in the Middle Jurassic.Through field work and indoor observation,the mineralization epoch is divided into 2 periods and 5 stages:(1)skarn period:(1)dry skarn stage;(2)wet skarn stage(forming enriched magnetite);(3)Oxide stage(forming a small amount of molybdenite).(2)quartz-sulfide period:(1)early sulfide stage(forming part of molybdenite);(2)late sulfide stage(forming mainly lead zinc sulfide such as sphalerite and galena).The alteration of surrounding rock mainly includes skarylation,epidotization,chloritization,silicification and ferritization.The surface tectonic alteration zone,iron cap,bare lead-zinc ore body and iron ore body are important markers of surface prospecting in this area.The high magnetic data in the mining area are processed by polarization,extension,horizontal first order derivative and vertical second order derivative,and interpreted line and ring structures.The processing results show that the tectonic framework is consist of trending NE and NW.The Jurassic granite is produced in trending NW,and the intermediate-acid volcanic rocks and volcanic sedimentary rocks of Guanghua Formation are distributed along trending NE.The study area can be divided into high value positive field zone,low gentle positive field zone and low gentle negative field zone,according to the characteristics of high magnetic anomaly.The high value positive field zone roughly corresponds to the ore-forming geological body: the Early to Middle Jurassic rock mass and the mineralized alteration formed by its intrusion into the Jixianggou Formation.The positive abnormal fields are mainly distributed in the NE and NW direction;the northeast of the area is dominated by negative abnormal fields,and several small positive abnormal fields are scattered;the southwest of the area is dominated by positive abnormal fields,and small negative abnormal fields appear locally;while the other parts of the area show the characteristics of alternating positive and negative abnormal fields.The NE and NW directions are the major fault structures in this area,and the intersection of the edge of the fault and ring structures control the output and distribution of ore bodies.The results of IP ladder show that the high and low impedance zones are distributed with each other in the study area,and the IP anomalies are mainly distributed in the northwest of the study area and trending NW.The statistical results of soil geochemical survey data in the mining area show that Pb,Zn,As,Sb and Mo are the main ore-forming elements with large coefficient of variation and high coefficient of concentration.The high background and abnormal areas of ore-forming elements are distributed in a NE-trending zonal pattern,which is controlled by the NE-tectonic and granitic bodies in the region.According to the results of systematic cluster and factor analysis,the ore-forming elements can be divided into five combinations:Pb-Zn-Ag-Cu,Sb-As,Fe,Mo and Au,which indicates that the ore-forming area has multi-stages superposition and enrichment characteristics.The known orebody is in the abnormal area of metallogenic element and factor score,which shows that it is an important prospecting indicator.Integrated the geological,geophysical and geochemical prospecting indicator information of the research area,the comprehensive information mineral prediction research shall be carried out.We established the comprehensive information mineral prediction model,and delineated 6 metallogenic prediction areas,to provide scientific direction for the next prospecting and exploration work. |
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