| Implications of micro-compositions of garnet and biotite from high-grade meta-pelites |
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| 引用本文： | ZHOU Xiwen,WEI Chunjing,and ZHANG Shangkun ( Institute of Geology,CAGS,Beijing 100037,China, School of Earth and Space Sciences,Peking University,Beijing 100871,China, China University of Geo-Sciences,Beijing 100083,China). Implications of micro-compositions of garnet and biotite from high-grade meta-pelites[J]. 自然科学进展(英文版), 2006, 16(2). DOI: 10.1080/10020070612330137 |
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| 作者姓名： | ZHOU Xiwen WEI Chunjing and ZHANG Shangkun ( Institute of Geology CAGS Beijing 100037 China School of Earth and Space Sciences Peking University Beijing 100871 China China University of Geo-Sciences Beijing 100083 China) |
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| 作者单位： | Institute of Geology，CAGS，Beijing 100037，China; School of Earth and Space Sciences，Peking University，Beijing 100871，China; China University of Geo-Sciences，Beijing 100083，China |
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| 摘 要： | Based on detailed studies on the compositional zoning of garnet and biotite in pelitic rocks from the Jingshan group of granulite facies in north Jiaodong, P-T pseudosections with isopleths of Fe/(Fe + Mg) in garnet and biotite were calculated in the KF-MASH system for two representative rocks of sillimanite-garnet-cordierite-biotite gneiss ( Vbi/ Vg>1 ) and sillimanite-garnet gneiss (Vbi/ Vg<0.2) using the software THERMOCALC and the internally consistent thermodynamic dataset. With a comparison of the calculated Fe/(Fe+ Mg) values in garnet and biotite in the peak P-T fields constrained by peak mineral assemblages with the measured ones, it is concluded that the coarse garnet crystals with diffusion zoning from high grade meta-pelites can preserve their peak compositions even when they have experienced a cooling event, and that biotite crystals surrounded by fetsic minerals in biotite-rich rocks with Vbi/Vg> 1 can nearly preserve their peak compositions, and biotites in garnet-rich rocks with Vbi/Vg<0. 2 cannot preserve their peak compositions due to the influence of grain-boundary fluid.
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Implications of micro-compositions of garnet and biotite from high-grade meta-pelites |
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| ZHOU Xiwen,WEI Chunjing,ZHANG Shangkun. Implications of micro-compositions of garnet and biotite from high-grade meta-pelites[J]. Progress in Natural Science, 2006, 16(2). DOI: 10.1080/10020070612330137 |
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| Authors: | ZHOU Xiwen WEI Chunjing ZHANG Shangkun |
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| Abstract: | Based on detailed studies on the compositional zoning of garnet and biotite in pelitic rocks from the Jingshan group of granulite facies in north Jiaodong, P-T pseudosections with isopleths of Fe/(Fe + Mg) in garnet and biotite were calculated in the KF-MASH system for two representative rocks of sillimanite-garnet-cordierite-biotite gneiss ( Vbi/ Vg>1 ) and sillimanite-garnet gneiss (Vbi/ Vg<0.2) using the software THERMOCALC and the internally consistent thermodynamic dataset. With a comparison of the calculated Fe/(Fe+ Mg) values in garnet and biotite in the peak P-T fields constrained by peak mineral assemblages with the measured ones, it is concluded that the coarse garnet crystals with diffusion zoning from high grade meta-pelites can preserve their peak compositions even when they have experienced a cooling event, and that biotite crystals surrounded by fetsic minerals in biotite-rich rocks with Vbi/Vg> 1 can nearly preserve their peak compositions, and biotites in garnet-rich rocks with Vbi/Vg<0. 2 cannot preserve their peak compositions due to the influence of grain-boundary fluid. |
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| Keywords: | high-grade meta-pelites THERMOCALC P-T pseudosection peak compositions of garnet and biotite |
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