The Analysis Of Geochemical Characteristics,Mineral Fluid And Material Source Of The Dawan Mo Deposit In The Northern Taihang Mountain

Dawan molybdenum deposit located in the west side of Laiyuan rock mass,and located in the Wulonggou fault.The history of mining is long,but the research level is not very high.On the basis of geological survey,this paper studies geological characteristics of the Dawan molybdenum deposit,geochemical characteristics of magmatic rocks related to mineralization,diagenetic age,characteristics of fluid inclusions,the mineral source and so on.Finally,this paper proposed the molybdenum mineralization model of Dawan molybdenum deposit through the analysis of mineralization process.By analysis of granite?rhyolite porphyry and quartz monzonite's main and trace element,the differentiation index(D1)of granite is 80.30-92.35,showing that magmatic differentiation degree is high,while negatively related P2O5 and SiO2 shows that the granites is type I.rhyolite porphyry and quartz monzonite's SiO2 content is rich,reflecting the consistency of different magmatic processes.The magma evolution produced a high differentiation degree.The rhyolite porphyry's total rare is low,and the degree of fractionation of rare earth elements is small.The light rare earth relative is enrich,and the degree of fractionation of quartz monzonite's rare earth elements is large.A weak Ce negative abnormality and a obvious Eu negative abnormality are popular in both rocks.Both are similar in the distribution of rare earth elements,indicating their causes are basically the same.The U-Pb age of Rhyolite porphyry is 141.02±0.39 Ma,and the U-Pb ages of quartz monzonite is 130.7±0.3 Ma.By analyzing the temperature of fluid inclusions,during the ore-forming fluid evolution,temperature,pressure and density is downward trend.Because the closure forming fluid system went into the open,due to the mine fissure expansion with the tectonic stress.Its density is decrease due to precipitation of minerals.The study of hydrogen and oxygen stable isotope indicates that in stage ? the mineralizing fluids were mainly magmatic water,but during stage ?the mineralizing fluids were mixed with precipitation.S?Pb?Re isotopes indicates that minerals of Dawan deposit are mainly deep source material,mainly from the upper mantle and lower crust,in part from the surrounding rock strata.Re-Os isotopic chronology shows that its mineralization age was 138±2Ma.In the mineralization process of evolution,there are mainly porphyry hydrothermal alteration system and mineralization contact metasomatic metamorphism system.Rhyolite porphyry is to provide a major source of minerals 5 but also extract part of a mineral deposit from the surrounding rock.It is the main ore rock.Through the analysis of mineralization process,metallogenic model of the deposit can be summarized as porphyry-skarn-hydrothermal vein-type.