Eclogitization of glaucophanites by fluid infiltration

The characteristic textures of eclogitic veins infilling the interstitial spaces among zoisite-glaucophanite pillows, the fractures crosscutting massive zoisite-glaucophanites and the relic conduits within the eclogite boudins demonstrate that the eclogitization of glaucophanites was accompanied by the presence of a free fluid phase in the Western Tianshan high-pressure metamorphic belt. Non-planar populations of fluid inclusions, parallel toC-axis, have been preserved within the omphacites in eclogitic veins. The microthermometric results indicate that fluids are low-salinity (1–4 wt%NaCl) aqueous fluids. The chemical compositions of major, trace and rare earth elements of eclogitic veins and related host rocks indicate that the eclogitization of glaucophanites required the addition of external Si and Na elements, and was accompanied by the loss of large-ion lithophile elements, rare earth elements and water. The record of eclogitization of glaucophanites along fractures and zones of high permeability by fluid infiltration has been preserved in the Wetsern Tianshan high-pressure metamorphic belt.