Rock association and its evolution in the Bixiling and Shuanghe areas in the Dabie UHP metamorphic terrane, southwestern Anhui

Bixiling and Shuanghe are two typical outcrop areas in the Dabie ultrahigh-pressure (UHP) metamorphic terrane. Based on field outcrop observations and petrographic and petrochemical studies, the authors find that the rock association consists predominantly of eclogite, amphibolite, gneiss and foliated garnet-bearing granite. Eclogite has the characteristics of the crustal source and is considered to form by UHP metamorphism crustal rocks in the deep interior of the mantle; amphibolite is the product of retrogressive metamorphism of eclogites during exhumation of the plate; gneiss was produced by anatexis and progressive evolution of amphibolite in an ideal environment during exhumation; and foliated garnet-bearing granite is the result of partial melting of gneiss. In conclusion, there is a reworked in-situ relationship between eclogite and gneiss (and/or foliated garnet-bearing granite).