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| Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals | |
| 引用本文： | 李曙光,刘贻灿,徐树桐,郑永飞. Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals[J]. 中国科学B辑(英文版), 2002, 45(Z1) |
| 作者姓名： | 李曙光 刘贻灿 徐树桐 郑永飞 |
| 作者单位： | School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China，School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China Anhui Institute of Geology Hefei 230001 China，Anhui Institute of Geology Hefei 230001 China，School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China |
| 基金项目： | 国家自然科学基金，国家重点基础研究发展计划(973计划)，Anhui Bureau of Geology and Mineral Resources |
| 摘 要： | The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhaifoliated peridotite has been recognized. The CaO concentrations of the garnet are decreased fromthe core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin ofsuch CaO-MnO zoning. The tie line of garnet+omphacite from this eclogite gives a Sm-Nd ageof (187±5) Ma, which is less significant than the Sm-Nd ages of (221±5)-(228±3) Ma and (210±6)-(214±6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northernDabie zone, respectively. This younger Sm-Nd age could result from the ~(143)Nd/~(144)Nd ratio decreaseof the retrograde zone in the garnet. The δ~(80)O values of the garnet and omphacite show that theirfractionation values are less than the equilibrium fractionation value between the garnet and om-phacite at 500-900℃, which suggests an oxygen isotopic disequilibrium between them. |
Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals |
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| LI Shuguang,LIU Yican. Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals[J]. Science in China(Chemistry), 2002, 45(Z1) | |
| Authors: | LI Shuguang LIU Yican |
| Affiliation: | 1. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China 2. School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China;Anhui Institute of Geology, Hefei 230001, China 3. Anhui Institute of Geology, Hefei 230001, China |
| Abstract: | The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin of such CaO-MnO zoning. The tie line of garnet + omphacite from this eclogite gives a Sm-Nd age of (187±5) Ma, which is less significant than the Sm-Nd ages of (221±5)-(228±3) Ma and (210±6)-(214±6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northern Dabie zone, respectively. This younger Sm-Nd age could result from the 143Nd/144Nd ratio decrease of the retrograde zone in the garnet. The δ18O values of the garnet and omphacite show that their fractionation values are less than the equilibrium fractionation value between the garnet and omphacite at 500-900℃, which suggests an oxygen isotopic disequilibrium between them. |
| Keywords: | eclogite Sm-Nd isotopic dating oxygen isotope zonation of garnet Dabie Mountains. |
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