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Type: Journal article
Title: The role of recycled oceanic crust in magmatism and metallogeny: Os-Sr-Nd isotopes, U-Pb geochronology and geochemistry of picritic dykes in the Panzhihua giant Fe-Ti oxide deposit, central Emeishan large igneous province, SW China
Author: Hou, T.
Zhang, Z.
Encarnacion, J.
Santosh, M.
Sun, Y.
Citation: Contributions to Mineralogy and Petrology, 2013; 165(4):805-822
Publisher: Springer
Issue Date: 2013
ISSN: 0010-7999
Statement of
Tong Hou, Zhaochong Zhang, John Encarnacion, M. Santosh, Yali Sun
Abstract: The picritic dykes occurring within fine-grained gabbro in the marginal zone and in the surrounding Proterozoic wall-rock marbles of the Panzhihua Fe–Ti oxide deposit closely correspond in bulk composition with the nearby Panzhihua intrusion. These dykes offer important constraints on the nature of the mantle source of the Panzhihua ore-bearing intrusion and its possible link to the Emeishan plume. U–Pb zircon dating of the picritic dyke yields a crystallization age of 261.4 ± 4.6 Ma, coeval with the timing of the main Panzhihua gabbroic intrusion and Late Permian Emeishan flood basalts. The Panzhihua picritic dykes contain 37.63–43.41 wt% SiO2, 1.15–1.56 wt% TiO2, 11.43–13.25 wt% TFe2O3, and 20.96–28.87 wt% MgO. Primitive-mantle-normalized patterns of the rocks are comparable to those of ocean island basalt. The rocks define a relatively small range of Os isotopic compositions and a low Os signature of −0.13 to +2.76 for γOs (261 Ma). In combination with their Sr–Nd–Os isotopic compositions, we interpret that these rocks were derived from the Emeishan plume sources as well as the interactions of plume melts with the overlying lithosphere which had been extensively affected by eclogite-derived melts from the deep-subducted oceanic slab. Partial melting induced by an upwelling mantle plume that involved an eclogite or pyroxenite component in the lithospheric mantle could have produced the parental Fe-rich magma. Our study suggests that plume-lithosphere interaction might have played a key role in generating many world-class Fe–Ti oxide deposits clustered in the Panxi area.
Keywords: Os–Sr–Nd geochemistry; Zircon U–Pb geochronology; Panzhihua; Emeishan; mantle sources; mineralization
Rights: © Springer-Verlag Berlin Heidelberg 2012
RMID: 0030044374
DOI: 10.1007/s00410-012-0836-3
Appears in Collections:Geology & Geophysics publications

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