Zircon U-Pb geochronology and isotopic geochemistry of the Tangjiaping Mo deposit, Dabie Shan, eastern China: Implications for ore genesis and tectonic setting

摘要

The Tangjiaping Mo deposit is located in the Dabie Shan in eastern China. Molybdenum (Mo) mineralization mainly occurs as veinlets in the Tangjiaping granite porphyry, which is featured by the development of potassic-silicic-, phyllic- and propylitic alterations. The Mo-mineralized granite porphyry, yields a zircon U-Pb age of 118.1 +/- 0.8 Ma (MSWD =1.6, 2 sigma, n = 24), and may have formed under post-collision extensional tectonics after the Yangtze-North China collision. The Tangjiaping granite porphyry is characterized by the enrichments of LILEs and LREEs, depletions of Ba, Nb, Ta, Sr, P, Ti and HREEs, and negative Eu anomaly. Zircons from the granite porphyry yield negative epsilon(Hf)(t) of -15.3 to -9.9, with T-DM2(Hf) ages of 1.80 to 2.14 Ga. The (206)pb/(204)pb, (207)pb/(204)pb and Pb-208/Pb-204 of the granite porphyry and its K-feldspar are 16.842-17.342,15.388-15.439 and 37.706-38.260, respectively, while those of the sulfides are 17.090-17.832,15.420-15.510, and 37.550-38.026, respectively. The delta S-34 of these sulfides exhibit a relatively narrow range of 3.2-4.9%., with an average of 4.0%.. The Hf-Pb-S isotopic signatures indicate that the granite porphyry and the ore-forming materials at Tangjiaping were mainly derived from the partial melting of both the Southern Dabie Complex and the Precambrian basement of the North China Craton. (C) 2016 Elsevier B.V. All rights reserved.