THE FATE OF SUBDUCTED CONTINENTAL CRUST: EVIDENCE FROM RECYCLED UHP-UHT MINERALS

Newly recognized occurrences of ultrahigh-pressure minerals in ultrahigh-temperature felsic granulites and in chromitite associated with ophiolite complexes lead to speculation about the recycling of supracrustal materials through deep subduction, mantle upwelling, and return to the Earth's surface. This idea is supported by possible "organic" light carbon isotopes observed in diamond and moissanite in kimberlite xenoliths and chromitite. These findings, presage another renaissance in the study of UHP granulite fades lower-crustal basement and ophiolites and in our understanding of the geodynamics of continental subduction and mantle cycling.