Discovery of super-silicic and super-titanic garnets in garnet-pyroxenite in Zhaheba and its geological significance

Super-silicic garnet which exists stably at more than 5 GPa is a typical ultra-high pressure mineral. The super-silicic garnet and super-titanic garnet were discovered for the first time in garnet-pyroxenite of early Paleozoic Zhaheba-Aermantai orogenic belt in north Xinjiang. Our study indicates that these super-silicic garnets as well as super-titanic garnets were formed at a depth of at least 300 km. Their host rock—garnet-pyroxenite is one kind of ultra-pressure metamorphic rocks which is related to the ultra-deep subduction of the oceanic crust. Thus, the early Paleozoic Zhaheba-Aermantai orogenic belt is related to the ultra-deep subduction of the Paleo-Asian oceanic crust. Supported by the National Natural Science Foundation of China (Grant No. 40673036), and Chinese Academy of Sciences (Grant Nos. KZCX2-YW-107 and GIGCX-04-03)