Origin of the Maoduan Pb-Zn-Mo deposit, eastern Cathaysia Block, China: Geological, geochronological, geochemical, and Sr-Nd-Pb-S isotopic constraints

The Maoduan Pb-Zn-Mo deposit is in hydrothermal veins with a pyrrhotite stage followed by a molybdenite and base metal stage. The Re-Os model ages of five molybdenite samples range from 138. 6 ± 2. 0 to 140. 0 ± 1. 9 Ma. Their isochron age is 137. 7 ± 2. 7 Ma. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating of the nearby exposed Linggen granite porphyry gave a 206Pb/ 238U age of 152. 2 ± 2. 2 Ma and the hidden Maoduan monzogranite yielded a mean of 140. 0 ± 1. 6 Ma. These results suggest that the intrusion of the Maoduan monzogranite and Pb-Zn-Mo mineralization are contemporaneous. δ 34S values of sulfide minerals range from 3. 4‰ to 4. 8‰, similar to magmatic sulfur. Four sulfide samples have 206Pb/ 204Pb = 18. 252-18. 432, 207Pb/ 204Pb = 15. 609-15. 779, and 208Pb/ 204Pb = 38. 640-39. 431, similar to the age-corrected data of the Maoduan monzogranite. These isotope data support a genetic relationship between the Pb-Zn-Mo mineralization and the Maoduan monzogranite and probably indicate a common deep source. The Maoduan monzogranite has geochemical features similar to highly fractionated I-type granites, such as high SiO 2 (73. 7-75. 2 wt.%) and alkalis (K 2O + Na 2O = 7. 8-8. 9 wt.%) and low FeO t (0. 8-1. 3 wt.%), MgO (~0. 3 wt.%), P 2O 5 (~0. 03 wt.%), and TiO 2 (~0. 2 wt.%). The granitic rocks are enriched in Rb, Th, and U but depleted in Ba, Sr, Nb, Ta, P, and Ti. REE patterns are characterized by marked negative Eu anomalies (Eu/Eu * = 0. 2-0. 4). The Maoduan monzogranite, having ( 87Sr/ 86Sr) t = 0. 7169 to 0. 7170 and ε Nd(t) = -13. 8 to -13. 7, was probably derived from mixing of partial melts from enriched mantle and the Paleoproterozoic Badu group in an extensional tectonic setting. © 2011 Springer-Verlag.