Eclogitization of glaucophanites by fluid infiltration

The characteristic textures of eclogitic veins infilling the interstitial s paces among zoisite-glaucophanite pillows, the fractures crosscutting massi ve zoisite-glaucophanites and the relic conduits within the eclogite boudin s demonstrate that the eclogitization of glaucophanites was accompanied by the presence of a free fluid phase in the Western Tianshan high-pressure me tamorphic belt. Non-planar populations of fluid inclusions, parallel to C-a xis: have been preserved within the omphacites in eclogitic veins. The micr othermometric results indicate that fluids are low-salinity (1-4 wt%NaCl) a queous fluids. The chemical compositions of major, trace and rare earth ele ments of eclogitic veins and related host rocks indicate that the eclogitiz ation of glaucophanites required the addition of external Si and Na element s, and was accompanied by the loss of large-ion lithophile elements, rare e arth elements and water. The record of eclogitization of glaucophanites alo ng fractures and zones of high permeability by fluid infiltration has been preserved in the Wetsern Tianshan high-pressure metamorphic belt.