Magmatic Geochemical Characteristics And The Mineralization Of Panjia Polymetallic Deposit, Zhejiang Province

Located in the northwest of Zhejiang province,Panjia polymetallic deposit is a newly discovered large-medium-sized W-Mo-Cu ore deposit at the north part of the Qinzhou Bay-Hangzhou Bay metallogenic belt.The Datongkeng pluton which produced in the certain district is characterized by SiO₂,K₂O and Na₂O concentrations ranging from 67.03 to 71.09%,2.453.03 to 4.89%and 0.24 to 3.37%respectively.The major elements display the peraluminous,high-K-Calcalkaline feature.Their A/CNK（A/CNK=n（Al₂O₃）/[n（CaO）+ n（Na₂O）+ n（K₂O）]）ratio,δEu,and δCe vary from 0.93 to 1.98,0.45 to 0.91 and 0.93 to 1.07,respectively.The rocks show enrichment in light rare earth elements（（La/Yb）N<10 except for one）and a depletion in Sr,Ba,Nb,P,Eu and Ti.The value of εNd（t）is-6.5～-3.9 with the model age of Nd ranging from 1.63Gm to 1.77Gm.The S isotopic dating displays a tower like distribution indicating the mantle source and the Pb element in pyrite and Datongkeng pluton has a linear relation.The temperature of crystallization of the pluton estimated from zircon thermometer ranges from 721 to 808℃.Molybdenite Re-Os dating shows that the Panjia deposit formed at 142.90±0.39Ma and 146.47Ma.Zircon U-Pb age indicates that the granodiorite formed at 150-154Ma during the multiperiod magmatism as the relevant diagenetic age.The diagenesis and the sources are correlated to mantle-crust interaction given priority to the crust,associated with the lithospheric thickening.The low-degree partial melting of the mantle source provided the most source of ore-forming materials.Finally two mineralization types formed including W-Mo polymetallic porphyritic deposit in Datongkeng pluton and W-Cu-Pb-Zn-Ag polymetallic deposit in Lantian Formation.