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Geochemistry and Petrogenesis of Granitoids at Sharang Eocene Porphyry Mo Deposit in the Main‐Stage of India‐Asia Continental Collision, Northern Gangdese, Tibet
Author(s) -
ZHAO Junxing,
QIN Kezhang,
LI Guangming,
LI Jinxiang,
XIAO Bo,
CHEN Lei
Publication year - 2012
Publication title -
resource geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 43
eISSN - 1751-3928
pISSN - 1344-1698
DOI - 10.1111/j.1751-3928.2011.00181.x
Subject(s) - geology , geochemistry , partial melting , quartz monzonite , petrogenesis , diorite , batholith , continental crust , petrology , crust , mantle (geology) , zircon , pluton , tectonics , paleontology
The Sharang porphyry Mo deposit is the first discovered Mo porphyry‐type deposit in the Gangdese Metallogenic Belt. The orebody is hosted by the Eocene multi‐stage composite intrusive complex which is emplaced in the Upper Permian Mengla Formation and cut by the Miocene dykes. Granite porphyry is recognized as the ore‐bearing porphyry in the complex, which consists of quartz diorite, quartz monzonite, granite, prophyritic granite and post‐mineral lamprophyre. Granodiorite porphyry and dacite porphyry intrude the granite porphyry. Geochemical data indicate that Sharang complex has a High‐K calc‐alkalinc to shoshonitic, metaluminous to slightly peraluminous composition. The Sharang complex rocks are enriched in large ion lithophile elements, depleted in high‐field strength elements, Nb, Sr, P and Ti. REE patterns show slight enrichments in light REE relative to heavy REE and weak negative Eu anomalies. All rocks in this complex have a wide range of initial 87 Sr/ 86 Sr ratios (0.705605∼0.712496) and lower ε Nd (t) values (−0.61∼−7.80). The geochemical data suggest highly oxidized‐evolved magma and old continental materials may have been the magma source for the Sharang intrusive complex that host porphyry Mo mineralization. Eocene pre‐ore and ore‐forming rocks at Sharang may have formed by partial melting of mantle wedge and by mixing with old continental crust at the lower crust level. In contrast the post‐ore rocks may have formed by partial melting of enriched lithospheric mantle.