The Characteristic of Petrology,minerals chemistry and P-T conditions of Eclogites from Talhu area in Dabie Mountains,and its Tectonic significance.

Eclogites from Taihu area in Dabie Mountains can be identified into HP(high pressure) eclogites,HP-UHP ( high/high- ultrahigh pressure) eclogites and UHP(ultrahigh pressure)elcogites,based on the result of geological mapping (1:10000) ,anti the investigation on the petrology,minerals chemistry and P-T conditions of these eclogites.From HP eclogites to UHP eclogites,the component of grossular and pyrope in garnet and Si~(4+)content of phengites rise gradually.Peak P-T conditions of eclogites also transform from 535℃～652℃,1.50～2.26GPa of HP eclogite,625℃～777℃,2.41～3.04GPa of HP/UHP eclogite to 767℃～942～,3.49～4.09GPa of UHP eclogites,and show a regional P-T gradient trend.Combine structure geometric characteristic in space and wall rocks of eclogites,application of Grt-Cpx thermometer and Grt-Cpx-Phe barometer,we define a 5℃/kin“geotherm”and two isopleth lines with T=650℃,P=2.50GPa;T=750℃,P=3.00GPa,and divided the South Dabie Terrain into three subzones: HP-Zone,HP-UHP-Zone and UHP-Zone,which imply the South Dabie Terrain is a consist terrain.According P-T paths of three types of eclogites in this study and previous chronology,we discuss different uplift rate of these eclogites tentatively,and guess that these eelogites can be shortened in the depth of 40～50kin and sealed as a“whole terrain”.Subsequently,this“whole terrain”ascends to the crust gently and forms the present distribution.