Rock-forming and ore-forming characteristics of the Lidongkeng porphyritic granodiorite in Xiuning County, south Anhui Province

Abstract: The Lidongkeng molybdenum deposit is located in Xiuning County, south Anhui Province. Accompanied by detailed geological description, this paper presents new ages and bulk-rock geochemistry for the Lidongkeng deposit. The LA-MC-ICP-MS zircon U-Pb age of 153.01 ± 0.90 Ma (MSWD = 1.14) for the ore-bearing porphyritic granodiorite and the Re-Os model age of 144.9±1.9 Ma (MSWD=2.0) for the molybdenite suggest that both of the ore body and the porphyry occurred during the Early Yanshanian period. According to the analyses of elements, the rock is rich in Si and K but poor in Mg, Ca and P and is characterized by high Rb and low Yb+Ta values, suggesting a collision environment. The porphyry is geochemically characterized by slight negative Eu anomaly. The porphyry shows I-type granite affinity. The molybdenite samples have Re content from 24.17 to 27.92μg.g-1, which implies that the molybdenum in the Lidongkeng deposit might have been derived from the crust with partial mixture of mantle materials.