Top boundary of the Dabie UHPM rocks, central China

Wang Qingchen, Liu Xiaohan, Shigenori Maruyama, Cong Bolin

    Research output: Contribution to journalArticle

    26 Citations (Scopus)

    Abstract

    The top boundary of the ultra-high pressure metamorphic (UHPM) rocks in the Dabie Mountains, central China, has been mapped. The results show that the top boundary of the UHPM rocks is occupied by flat-lying felsic gneiss, on which tonalitic gneiss rests. Petrological and mineralogical evidence indicates a wide P-T gap across the boundary with an estimated peak metamorphic P-T value of the UHPM rocks being >30 kbar and 800 ± 50°C, and that of the tonalitic gneiss around 11 kbar and 800°C. Their P-T-t paths are different. The former has a clockwise path and the latter is counterclockwise. This implies that the UHPM rocks at the bottom and the tonalitic gneiss on top have been structurally juxtaposed together. The top boundary, i.e. the contact between the UHPM rocks and tonalitic gneiss, shows characteristics of a ductile shear zone. Microscopically, feldspar and quartz in the shear zone are characterized by ductile deformation. In larger scale, the top boundary is undulating. Shear sense in the top boundary is a two-way direction. Only the latest shear sense measured with c-axes of quartz show a consistent direction of top-to-the-north. The study provides some constraints to the exhumation process of the Dabie UHPM rocks.

    Original languageEnglish
    Pages (from-to)295-300
    Number of pages6
    JournalJournal of Southeast Asian Earth Sciences
    Volume11
    Issue number4
    DOIs
    Publication statusPublished - May 1995

    ASJC Scopus subject areas

    • Environmental Science(all)
    • Earth and Planetary Sciences (miscellaneous)
    • Earth and Planetary Sciences(all)

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