Comparative Study On Geochemistry Of Geological And Metallogenic Rocks Of Dongyuan And Jiangjia Porphyry Type Tungsten Molybdenum Ore In Anhui

The Dongyuan deposit is a large porphyry type tungsten molybdenum deposit in the eastern part of the Jiangnan paleo continental tungsten ore belt.Jiangjia molybdenum deposit is a mineralization point adjacent to the Dongyuan deposit.At present,the mineralization age of Jiangjia molybdenum deposit has not been determined.The cause of mineralization difference between Dongyuan and Jiangjia deposits has not been identified yet.In this paper,a comparative study of the age of diagenesis and mineralization,the main geochemical characteristics of the rocks and the geochemical characteristics of Sr-Nd-Hf isotopes of the Dongyuan tungsten molybdenum ore and Jiangjia molybdenum deposit are carried out to interpret the fundamental reasons for the interpretation of the mineralization differences and the scale of the ore deposits in the Dongyuan molybdenum ore and Jiangjia molybdenum ore.LA – ICP – MS zircon U Pb dating indicates that Dongyuan granodiorite was formed at 152.03 + 0.84 Ma,and Jiangjia granodiorite was formed at 149.3 + 1.1Ma.The Re-Os isotope age of Molybdenite in the Jiangjia orebody is 147.9 + 6.4Ma,which is closely related to the late Jurassic magmatism.The granodiorite in Dongyuan and Jiangjia belong to weak partial aluminous,Dongyuan rock A/CNK=1.00-1.04 and Jiangjia rock A/CNK=1.00-1.03,which are high potassium calc alkaline series,P2O5 content and Si O2 content are negatively correlated,and belong to the typical I type granite.The initial 87Sr/86 Sr and Nd(T)values of the Dongyuan and Jiangjia granodiorites are 0.7113 ? 0.7155 and 6.80? – 5.46.The occurrence of Neoproterozoic inherited zircons(weighted average age of 815.8 + 6.26Ma)indicates that the magma source area is the Neoproterozoic ancient crust basement.The epsilon Hf value(-13.0?-7.0)of the Dongyuan rock mass is obviously lower than the Jiangjia rock mass(-5.63?-2.42),and the ISr value of the Dongyuan rock mass(0.71315-0.71554)is obviously larger than the ISr value of the Jiangjia rock mass(0.71147-0.71220),indicating that the proportion of the ancient crustal material in the formation of the Dongyuan rock mass is greater than the Jiangjia rock mass,and the formation of the Jiangjia rock may have more mantle.Magma participates.The enriched ancient crustal material is an ideal magma source area for the metallogenic related rock mass of the tungsten deposit.Therefore,one of the reasons for the difference of the two mineralization may be that the initial magma of the Dongyuan rock mass is more favorable to the formation of tungsten deposits than the initial magma of the Jiangjia rock mass.The outcropping area of the Dongyuan rock mass is small,the alteration scale is large and the intensity is high.The outcropping area of the Jiangjia rock mass is large,the alteration scale is small and the strength is low.The Dongyuan ore body has the characteristics of "upper tungsten molybdenum" like layer distribution.There is no tungsten mineralization in Jiangjia mining area and only the distribution of molybdenum ore body.The other reason is that the two cause of the mineralization difference is East.The erosion degree of source rock mass is lower than that of Jiangjia rock mass,and the larger scale tungsten molybdenum ore body is retained.The Yanshan magmatic activity in the southern uplift zone of Southern Anhui Province is divided into two phases(160-135 Ma and 135-120Ma),and the Dongyuan and Jiangjia porphyry tungsten deposits are the early magmatism products of Yanshan.The formation of the magmatic activity is caused by the slanting subduction of the Pacific plate to the continental plate and the fracture of the plate near the plate window.The mass is fused and formed by the mixing of the crust and mantle.