Crustally-derived granites in the Panzhihua region, SW China: Implications for felsic magmatism in the Emeishan large igneous province

J.g  Shellnutt, Bor Ming Jahn, Mei Fu Zhou

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    59 Citations (Scopus)

    Abstract

    In the Panxi region of the Late Permian (~260Ma) Emeishan large igneous province (ELIP) there is a bimodal assemblage of mafic and felsic plutonic rocks. Most Emeishan granitic rocks were derived by differentiation of basaltic magmas (i.e. mantle-derived) or by mixing between crustal melts and primary basaltic magmas (i.e. hybrid). The Yingpanliangzi granitic pluton within the city of Panzhihua intrudes Sinian (~600Ma) marbles and is unlike the mantle-derived or hybrid granitic rocks. The SHRIMP zircon U-Pb ages of the Yingpanliangzi pluton range from 259±8Ma to 882±22Ma. Younger ages are found on the zircon rims whereas older ages are found within the cores. Field relationships and petrography indicate that the Yingpanliangzi pluton must be <600Ma, therefore the older zircons are interpreted to represent the protolith age whereas the younger analyses represent zircon re-crystallization during emplacement. The Yingpanliangzi granites are metaluminous and have negative Ta-NbPM anomalies, low εNd(260 Ma) values (-3.9 to -4.4), and high ISr (0.71074 to 0.71507) consistent with a crustal origin. The recognition of a crustally-derived pluton along with mantle-derived and mantle-crust hybrid plutons within the Panxi region of the ELIP is evidence for a complete spectrum of sources. As a consequence, the types of Panxi granitoids can be distinguished according to their ASI, Eu/Eu*, εNd(T), εHf(T), TZr(°C) and Nb-TaPM values. The diverse granitic magmatism during the evolution of the ELIP from ~260Ma to ~252Ma demonstrates the complexity of crustal growth associated with LIPs.

    Original languageEnglish
    Pages (from-to)145-157
    Number of pages13
    JournalLithos
    Volume123
    Issue number1-4
    DOIs
    Publication statusPublished - 2011 Jan 1

    Keywords

    • Aluminum saturation index
    • Crustal melting
    • Emeishan large igneous province
    • Granite
    • Late Permian
    • Zr saturation thermometry

    ASJC Scopus subject areas

    • Geology
    • Geochemistry and Petrology

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