Zircon U-Pb dating,Lu-Hf isotopes and petrogeochemistry of the Dazeshan pluton from the northwestern Jiaodong Peninsula
The Jiaodong Peninsula is one of the most important gold mineralization areas in China,and the large-scale gold mineralization occurred from 125 Ma to 110 Ma.In this paper,the Early Cretaceous Dazeshan pluton,emplaced coevally with the gold mineralization,is selected to reveal its petrogenesis using detailed lithography,petrogeochemistry and zircon LA-ICP-MS U-Pb chronology.Medium grained monzogranite and fine grained monzogranite are identified in Dazeshan pluton.They have similar petrographic and geochemical characteristics,showing the characteristics of homologous magmatic evolution.Zircon U-Pb dating yields 119.8± 0.8 Ma and 119.3±0.9 Ma for the medium grained monzogranite,109.2±0.7 Ma and 109.9±0.7 Ma for the fine grained monzogranite.Petrogeochemistry studies show that:monzogranite possess high total alkalis(K2O+Na2O=8.14％～8.72％),with high Al2O3 content(12.42％～15.32％),the granites belong to peraluminious high-K calc-alkaline feature,enrichment in LREEs,relative depletion in HREEs(LREE/HREE=8.46～18.87),as well as significant rare earth element fractionation((La/Yb)N=8.52～24.08)and with pronounced negative Eu anomalies(δEu=0.33～0.58).The Dazeshan pluton has low zircon εHf(t)values of-26.4～-16.2,and two-stage Hf model ages(TDM2)vary in range of 2 812～2 173 Ma.The diagenetic material is mainly derived from the partial melting of the Paleoproterozoic and Neoarchean crustal materials with the addition of some mantle materials.The diagenetic period of Dazeshan pluton is consistent with the main metallogenic period of Jiaodong gold deposit,suggesting that magmatism and gold mineralization have the same geodynamic setting.
万方数据
维普
