Title: Re–Os and U–Pb geochronology of porphyry Mo deposits in central Jilin Province: Mo ore-forming stages in northeast China
Abstract: AbstractCentral Jilin Province lies along the eastern edge of the Xing–Meng orogenic belt of northeast China. At least 10 Mo deposits have been discovered in this area, making it the second-richest concentration of Mo resources in China. To better understand the formation and distribution of porphyry Mo deposits in the area, we investigated the geological characteristics of the deposits and applied zircon U–Pb and molybdenite Re–Os isotope dating to constrain the age of mineralization. Our new geochronological data show the following: the Jidetun Mo deposit yields molybdenite Re–Os model ages of 164.6–167.1 Ma, an isochron age of 168 ± 2.5 Ma, and a weighted mean model age of 165.9 ± 1.2 Ma; the Houdaomu Mo deposit yields molybdenite Re–Os model ages of 167.4–167.7 Ma, an isochron age of 168 ± 13 Ma, and a weighted mean model age of 167.5 ± 1.2 Ma; and the Chang'anpu Mo deposit yields a zircon U–Pb age for granodiorite porphyry of 166.9 ± 1.5 Ma (N = 16). These new age data, combined with existing molybdenite Re–Os dates, show that intense porphyry Mo mineralization was coeval with magmatism during the Middle Jurassic (167.8 ± 0.4 Ma, r > 0.999). The geotectonic mechanisms responsible for Mo mineralization were probably related to subduction of the Palaeo-Pacific plate beneath the Eurasian continent. Combining published molybdenite Re–Os and zircon U–Pb ages for northeast China, the Mo deposits are shown to have been formed during multiple events coinciding with periods of magmatic activity. We identified three phases of mineralization, two of which had several stages: the Caledonian (485–480 Ma); the Indosinian comprising the Early–Middle Triassic (248–236 Ma) and Late Triassic (226–208 Ma) stages; and the Yanshanian phase comprising the Early–Middle Jurassic (202–165 Ma), Late Jurassic–early Early Cretaceous (154–129 Ma), and Early Cretaceous (114–111 Ma) stages. Although Mo deposits formed during each phase/stage, most of the mineralization occurred during the Early–Middle Jurassic.Keywords: Re–Os and U–Pb geochronologyporphyry molybdenum depositsmineralization periodscentral Jilin Provincenortheast China AcknowledgementsWe thank the staff of the National Research Centre of Geoanalysis, Chinese Academy of Geological Sciences, and the State Key Laboratory of Continental Dynamics, Northwest University, Xi'an, China, for Re–Os and U–Pb zircon analysis dating. In particular, we express our gratitude to the reviewers for their critical reviews and excellent suggestions which provided for the improvement of this article. This work was jointly supported by the Project for Scientific and Technology Development (Grant No. 20100450), the National Natural Science Foundation of China (Grant No. 41172072), and the Chinese Geological Survey Programme (Grant No. [2010]01-26-06).
Publication Year: 2013
Publication Date: 2013-05-10
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 41
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