| Retrogressive Microstructures of the Eclogites from the Northern Dabie Mountains, Central China： Evidence for Rapid Exhumation |
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| 作者姓名： | LiuYican LiShuguang XuShutong ChenGuanbao |
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| 作者单位： | [1]SchoolofEarthandSpaceSciences,UniversityofScienceandTechnologyofChina,Hefei230026,China [2]AnhuiInstituteofGeology,Hefei230001,China |
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| 基金项目： | Chinese National Key Project for Basic Research，国家重点基础研究发展计划(973计划)，国家自然科学基金 |
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| 摘 要： | The ultrahigh-pressure eclogites from the northern Dabie Mountains in central China occurred as tectonic lens or blocks within granitic gneisses or meta-peridotites. Petrologic studies suggest that the studied eclogites experienced strongly retrogressive metamorphism and produced a series of characteristic retrogressive microstructures. The retrograde structures mainly include: (1) oriented needle mineral exsolution, e. g. , quartz needles in Na-clinopyroxene and rotile, clinopyroxene and apatite exsolution in garnet formed under decreasing pressure conditions during exhumation; (2) symplectite, especially, two generations of symplectites developed outside the garnet grains, which are called ““double symplectite““ here; (3) compositional zoning of minerals such as garnet and clinopyroxene; (4) minerals with a reaction rim or retrograde rim, e.g. , omphacite with a diopside rim, diopside with an amphibole rim and rutile with a rim of ilmenite. These retrograde textures, especially mineral zoning and symplectite, provide important petrologic evidence for the exhumation process and uplift of high-grade metamorphic rocks such as eclogite in the northern Dabie Mountains, indicating a rapid exhumation process.
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| 关 键 词： | 榴辉岩 变质作用 微观结构 大别山 地质挖掘 |
Retrogressive Microstructures of the Eclogites from the Northern Dabie Mountains, Central China:Evidence for Rapid Exhumation |
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| LiuYican LiShuguang XuShutong ChenGuanbao.Retrogressive Microstructures of the Eclogites from the Northern Dabie Mountains, Central China:Evidence for Rapid Exhumation[J].Journal of China University of Geosciences,2004,15(4):349-354. |
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| Authors: | LIU Yican Li Shuguang XU Shutong Chen Guanbao |
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| Abstract: | The ultrahigh-pressure eclogites from the northern Dabie Mountains in central China occurred as tectonic lens or blocks within granitic gneisses or meta-peridotites. Petrologic studies suggest that the studied eclogites experienced strongly retrogressive metamorphism and produced a series of characteristic retrogressive microstructures. The retrograde structures mainly include: (1) oriented needle mineral exsolution, e.g., quartz needles in Na-clinopyroxene and rutile, clinopyroxene and apatite exsolution in garnet formed under decreasing pressure conditions during exhumation; (2) symplectite, especially, two generations of symplectites developed outside the garnet grains, which are called "double symplectite" here; (3) compositional zoning of minerals such as garnet and clinopyroxene; (4) minerals with a reaction rim or retrograde rim, e.g., omphacite with a diopside rim, diopside with an amphibole rim and rutile with a rim of ilmenite. These retrograde textures, especially mineral zoning and symplectite, provide important petrologic evidence for the exhumation process and uplift of high-grade metamorphic rocks such as eclogite in the northern Dabie Mountains, indicating a rapid exhumation process. |
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| Keywords: | retrogressive microstructure rapid exhumation eclogite northern Dabie Mountains China |
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