The Lanshantou kyanite-bearing eclogite with coesite inclusions in the Sulu ultrahigh-pressure metamorphic belt and its PTt path

Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induce d by strong compression of the Yellow Sea terrane to the Jiaodong-northerea stern Jiangsu terrane during the interaction of the Eurasian plate and Pala eo-Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B a nd C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The Mao, CaO and FeO contents in garnet and pyroxene show regular variation fr om the core to the rim, which reveals the PTt paths of progressive metamorp hism during the Early Mesozoic (240-200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.