Geological Characteristics And Prospecting Prediction Of Weishan REE Deposit In Shandong Province

Focusing on the geological characteristics and metallogenic prediction of the weishan rare earth?REE?deposit,the paper focuses on the structural,magmatic rocks and ore body characteristics in the mining area.After systematically analyzing and summarizing the scientific research achievements of the predecessors,based on the geochemical and isotopic characteristics of rock elements,the tectonic environment of diagenesis and mineralization,the source of diagenesis and mineralization materials etc.are studied.Based on the analysis and reprocessing of the Gamma energy spectrum measurement data and combining with the previous geological exploration results,the prospecting prediction and evaluation work is carried out in chishan mining area.Through research,the main results and knowledge obtained are as follows.The orebody of the Weishan chishan rare earth deposit generally consists of a series of northwestward and westward steep dip veins,which is present in the northwestward faulting structural zone and in the gneiss-like granodiorite on the top and bottom of alkaline rock bodies.The ore veins are mostly barite crystals containing fluorinated carbon cerium ore,and the northwest and northeast faults are ore-conducting and ore-holding structures,which are generally structure before or during metallogenesis.The ore minerals are dominated by bastnaesite,parisite and monazite,and they form symbiotic veins with calcite,barite,quartz,pyrite and so on.The surrounding rocks are gneiss-like granodiorite and orthoclase.Alkaline metasomatic alteration and rare earth mineralization are obvious.The more surrounding rock fractures,the greater the minerality.The diagenetic age of the syenite in the mining area is Early Cretaceous?120-130Ma?and the metallogenic age is?110-120Ma?,indicating that the deposit may have a genetic relationship with magmatic rocks.The geochemical characteristics of the magmatic rock elements and isotopes indicate that the diagenetic magma is derived from enriched mantle and mixed with a small amount of crustal material.The alkaline complex formed in the transitional tectonic environment in which the southeast edge of the active craton of the North China Plate changed from a compression-based to a tension-based tectonic mechanism,which is the product of alkaline magmatism during the extension period of the Pacific Plate to the North China Plate after the subduction collision.The characteristics of fluid inclusions in minerals of the ore veins indicate that the temperature of ore-forming fluids evolved from high-medium temperature,high salinity to low temperature and low salinity from early to late mineralization.The properties of Weishan rare earth ore-forming fluids are high-medium temperature,high concentration,which is rich in CO₂,SO₄^2-,REE and contains CO₃^2-,F^-and Na⁺,K⁺,Ca²⁺,Sr²⁺,Ba²⁺.The ore-forming fluids are separated from the alkaline-carbonate magma,and the ore-forming materials are derived from the enriched mantle.Prospecting through geological analysis and interpretation of the geophysical anomaly of Weishan rare earth deposit,the prediction basis was put forward,and the target area was delineated and evaluated.In addition to the anomalies in the ore area,7 anomalous areas with ore prospecting significance were found in the periphery,and 2 target areas were delineated in the Weishan Chishan rare earth ore area and the periphery.Based on the possible depth of the ore body and previous exploration results,it is found that the possibility of deep vein extension in the mining area is greater.The deep metallogenic potential of target areas?-2 and?-3 is greater.The result of deep engineering verification is good.Shallow project control in the southwest of Target?-3 is low,but individual projects have verified that veins are present in the shallow part.Therefore,the deep and peripheral areas of Weishan rare earth mining area have greater prospecting potential.