| 大别山榴辉岩氢氧同位素组成及其地球动力学意义 |
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| 关键词:oxygen hydrogen isotopes meteoric water geochemical recycling geodynamics ultrahigh pres_ sure eclogite the Dabie mountains |
| 基金项目:国家自然科学基金,中国科学院专项基金 |
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| 摘要: |
| Hydrogen and Oxygen Isotope Compositions of Eclogites from the Dabie Mountains and Its Geodynamic Implications |
| Heterogeneous δ 18 O values as low as -2.6‰ to +7.0‰ are observed for ultrahigh pressure eclogites from the Dabie mountains in East China.Oxygen isotope equilibriun has been approached between the eclogite minerals,suggesting that the rocks would have acquired the unusual δ 18 O values prior to ultrahigh pressure metamorphism by interaction with a 18 O depleted fluid . δ D values of hydroxyl bearing are between-51‰ and -83‰, precluding the possibility of paleoseawater involvement.The only likely fluid is ancient meteoric water that exchanged oxygen isotopes with the eclogite precursor(a kind of basaltic rocks)formerly resident in the continental crust.This suggests a crustal recycling process in the suture zone of plate subduction.Because silicate minerals undergo rapid oxygen isotope exchange at mantle pressures,preservation of the isotopic signature of meteoric water in the eclogites indicates limited crust_mantle interaction and thus a short residence time(<20 Ma)when the plate containing the eclogite precursor was subducted to mantle depths .The agreement in oxygen isotope temperatures for different mineral pairs suggests a rapid cooling and ascent process for the eclogites subsequent to their formation at mantle depths. |
| ZHENG Yong-fei,FU Bin,XIAO Yi-lin,GONG Bing,GE Jie-ning,LI Shu-guang.1997.Hydrogen and Oxygen Isotope Compositions of Eclogites from the Dabie Mountains and Its Geodynamic Implications[J].Acta Geoscientica Sinica,18(3):336. |
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