Paleoproterozoic metamorphic evolution of the Yangtze Craton: Evidence from the Huangling Dome garnet-amphibolite
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P588.12+5

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    Abstract:

    In order to explore the characteristics of metamorphism and the tectonic setting in the Yangtze Craton, we carried out petrographic, geochemical and chronological studies on the garnet-amphibolite in the north of the Huangling Dome. The results show that the main minerals in the garnet-amphibolite are garnet, plagioclase, amphibole, cliniopyroxene, quartz and ilmenite, in which the mineral assemblages of 3 different metamorphic stages are retained. The prograde metamorphic stage is characterized by the assemblage of amphibolite+plagiospar+quartz+ilmenite and the peak metamorphic stage consists of garnet+amphibole+plagioclase+clinopyroxene+quartz+ilmenite, while the retrograde assemblage contains garnet+amphibole+plagioclase+quartz+ilmenite. The garnet-amphibolite protolith belongs to subalkaline tholeiite with low Mg#, indicating that its protolith has experienced a degree of differentiation. By means of conventional geological thermometer, the temperature and pressure conditions of different metamorphic stages were calculated. We obtained the p-t conditions of 596~625℃ and 0.70~0.82 GPa for the prograde metamorphic stage, 760℃ and 1.35 GPa for the peak metamorphic stage, and 692~738℃ and 0.68~0.74 GPa for the retrograde metamorphic stage. Meanwhile, a clockwise p-t path was represented from these p-t conditions, showing the process of warming and pressurization to the peak and then a near isothermal decompression. This p-t path reflects the tectonic setting of subduction-collision at the convergent plate margin. U-Pb dating of zircons in the garnet-amphibolite yields a harmonic age of 2 008±11 Ma. Together with the existing metamorphic ages in the region, these ages reveal that the Yangtze Craton was involved in the splicing of microcontinental blocks during the Paleozoic, which might be a response of the Columbia supercontinent assembly.

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付强,魏君奇,范堡程,裴康达,2023,扬子克拉通古元古代变质演化——来自黄陵穹窿石榴斜长角闪岩的证据[J].岩石矿物学杂志,42(2):173~190. FU Qiang, WEI Jun-qi, FAN Bao-cheng, PEI Kang-da,2023,Paleoproterozoic metamorphic evolution of the Yangtze Craton: Evidence from the Huangling Dome garnet-amphibolite[J]. Acta Petrologica et Mineralogica,42(2):173~190.

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History
  • Received:October 13,2022
  • Revised:February 04,2023
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  • Online: March 22,2023
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