Abstract:Intergranular rutiles from six UHP eclogites in the Dabie orogen were investigated by Micro-FTIR and EMP analysis. The results show that all grains show two strong absorbance bands at 3280 cm-1 and 3295 cm-1, withan occasional weak and wide absorbance band at ～3360 cm-1, which are all ascribed to structural OH. Comparisons with the results of HT-HP experiments indicate that the 3280 cm-1 band is caused by Ti3+ +H <—>Ti4+substitution, the 3295 cm-1 band is attributed to Fe3+ +H<—>Ti4+ substitution, and the ～3360 cm-1 band is possibly related to Mg2+ +2H<—>Ti4+. The calculated water contents (expressed as H2O wt.) based on two reliable IR absorbance coefficients are 161×10-6～854×10-6 and 202×10-6～1075×10-6respectively, and the results will increase by about 4～5 times if other absorbance coefficients are applied. Hence the relatively high water content in literature should be considered carefully. Similar to coexisting garnet and omphacite, heterogeneous distribution of water on the outcrop scales in rutiles implies a very limited fluid mobility during UHP metamorphism and a quick subduction and exhumation process.
