Mineral Inclusions in Zircons from UHP Metamorphic Rocks, Northeastern Sulu Terrane, China

The metamorphic rocks distributed on the northeastern Sulu UHP terrane, consist mainly of eclogite, amphibolite, orthogneiss and paragneiss, with thin layers and blocks of marble, mica-bearing schist and camgit metamorphic rocks. All analyzed (except eclogite) samples are overprinted by amphibolite-facies retrogression. However, coesite-bearing UHP minerals as inclusions in zircons from 132 outcrop samples have been identified using laser Raman spectroscopy and cathodoluminescence (CL) image analysis. Similarly, zircons separated from cores in drilling holes and outcrops around Donghai and adjacent area, southwestern Sulu terrane also contain abundant coesite-bearing UHP mineral inclusions. These evidences suggest that the voluminously continental materials (~320 km×20 km×5 km), mainly consisting of protolithes of eclogite and country-rocks, commonly occurred deep-subduction, experienced ultrahigh-pressure metamorphism, and then rapidly returned to the earth's surface.