Characteristics Of Graphite Deposits In Datian Area Of Panzhihua And Their Relationship With Uranium Deposits

The graphite deposit in the Datian area is located in the middle of the Kang Dian-Axis,and the south east wing of the Datian anticline.The Kang Dian-Axis is located on the western edge of the Yangtze platform.Its geological conditions are complex,structural faults are developed,and mineral resources are abundant.It is a key area for mineral resources research.This paper analyzes the geological and geochemical characteristics of graphite mines in Datian area by conducting field geological surveys,determination of ordinary trace elements,zircon U-Pb dating,and carbon isotope analysis,and the relationship between the graphite deposits and uranium deposits was discussed.The main knowledge gained is as follows.(1)Graphite deposits in the Datian area are mainly produced in plagioclase gneiss,mixed rocks,and contact sites of felsic veins.Ore-bearing lithology is plagioclase gneiss,mica quartz schist,etc.Graphite ore bodies are often layered,layered or lenticular.Graphite mainly has a flaky crystal structure,and the particle size is mainly in the range of 0.15-3mm.The gangue minerals are mainly quartz and mica.(2)The ore-bearing rock series has the characteristics of high silicon and aluminum,low total alkali content,and poor iron and magnesium,and the loss on ignition increases with the decrease of each oxide.According to the DF discriminant formula and related graphical analysis,the original rock containing ore-bearing rocks shows parametamorphic rocks,and some samples are in the transition zone between volcanic rocks and sedimentary rocks.The trace element characteristics show that the source of ore-bearing rocks originates from the upper crust,the deposition environment is anoxic-weak reducing environment,and the content of radioactive elements is high.It is presumed that the original rocks are argillaceous sedimentary rocks or felsic mudstones.The total amount of rare earth elements is higher than that of chondrites.The distribution curve generally shows that the light rare earth is relatively enriched,and the heavy rare earth is relatively right-inclined.The Eu element presents a significant negative anomaly,and the Ce element presents a significant weak negative anomaly.Carbon isotope?¹³C values range from-19.7‰to-23.9‰,with an average of-20.9‰.Compared with other graphite samples,it is shown as organic carbon.(3)The zircon U-Pb age shows that the zircons in the graphite-bearing mica-quartz schist have both metamorphic new zircons and ancient inherited zircons.The age was839.7±7.4(n=11),and the time span was large.The zircons in the fetal veins are mainly magmatic zircons,with an age of 761.8±6.4Ma(n=26).Graphite mineralization mainly occurred in the Neo-Early times,and overlaps with the time of mixed lithification,suggesting that mixed lithification and the infusion of the fetal veins played a role in increasing the diameter of the graphite sheet.(4)The Datian graphite deposit is mainly controlled by lithology and strata,and the uranium deposit is mainly controlled by structure and fractures.In space,the two areas overlap.Graphite mineralization formed earlier,and the age of uranium ore is774.9-785.5Ma,which is slightly later than graphite ore.Graphite deposits are formed by argillaceous sedimentary rocks and perilithic mud-sandstones.They are affected by mixed petrification,structure,and hydrothermal action in the later period,and their diameter increases.Uranium ore is formed by enrichment of U elements in surrounding rocks due to hydrothermal fluid filling structures and fractures in the late stage of mixed lithification.The ore-bearing rock series of graphite is part of the surrounding rock formed by uranium ore.