An Important Carrier of High-Pressure and Ultrahigh-Pressure Metamorphic Fluids: Nominally Anhydrous Minerals

Qunke Xia, Daogong Chen
Chinese Academy of Sciences Key Laboratory of Crust-Mantle Materials and Environments
School of Earth and Space Sciences,
University of Science and Technology of China, Hefei, Anhui Province, 230026, China. 

George R. Rossman
Division of Geological and Planetary Sciences, California Institute of Technology
Pasadena, California, USA 91125

Xiachen Zhi, Hao Cheng, Yuanbao Wu
Chinese Academy of Sciences Key Laboratory of Crust-Mantle Materials and Environments
School of Earth and Space Sciences,
University of Science and Technology of China, Hefei, Anhui Province, 230026, China.

Abstract

Garnets and omphacites from three pieces of eclogites from the Dabie Mt. have been investigated by the Fourier transform infrared spectrometer (FTIR). All these minerals contain structural water which occur as hydroxyl (OH- ). The results demonstrate that nominally anhydrous minerals can bring water into the depth during deep crust subduction; the structural water in such minerals can be the part of metamorphic fluids; even in the ultra-high pressure stage, the metamorphic system is not "dry".