Geological Characteristics and Molybdenite Re-Os Isotopic Dating of Antuoling Molybdenum Deposit in Hebei Province

The Antuoling molybdenum deposit in Hebei Province is located in the northern part of the Taihang mountain region in China. It is one of the well-known molybdenum deposits in Yanshan-Liaoning molybdenum ore belt. The main ore-forming types in the deposit include veinlet,film-like,and disseminated molybdenite mineralization,and the mineralization is mainly situated in inner porphyry body and outer contact belts. Hydrothermal alteration is well developed and is composed of silicification,pyritization,sericitization,pyritizationsericitization and propylitization,with the characteristics of typical porphyry Mo deposits. Re-Os dating of five samples from the Antuoling porphyry-type deposit yield the model age ranging from( 145. 7 ± 2. 4) to( 148. 8 ± 2. 6) Ma,with the average model age of( 146. 9 ± 1. 0) Ma. The isochron age of( 147. 3 ± 3. 7) Ma( initial 187Os =(- 0. 4 ± 2. 6) ng / g,and MSWD = 1. 5) indicates that molybdenum mineralization was formed in Late Jurassic and had spatially and temporally associated with the tectonomagmatic orogenic process in middle-late Yanshanian period in which it is coincident with the large-scale metallogenic event happened in 140 Ma in the northern part of China. The Re contents of the samples ranging from 50. 42 × 10- 6to 104. 9 × 10- 6,and the δ34S values of the sulphur isotope ranging from 0. 7‰ to 2. 8‰,indicate that the ore-forming materials were derived from mixed crust and mantle sources. The Antuoling molybdenum deposit was formed in the Mesozoic second large-scale mineralization period of North China. It is the consequence of the tectonic regime changingfrom compression to extension.