Recycling of crustal materials through study of ultrahigh-pressure minerals in collisional orogens, ophiolites, and mantle xenoliths: A review

摘要: Abstract Newly recognized occurrences of ultrahigh-pressure (UH P ) minerals including diamonds in ultrahigh-temperature T felsic granulites orogenic belts, chromitites associated with ophiolitic complexes, and mantle xenoliths suggest the recycling crustal materials through deep subduction, upwelling, return to Earth’s surface. This circulation process is supported by crust-derived mineral inclusions deep-seated zircons, chromites, from collision-type orogens, eclogitic kimberlites, chromitities several Alpine–Himalayan Polar Ural ophiolites; some these contain low-atomic number elements typified isotopic signatures. Ophiolite-type placer deposits as together numerous highly reduced alloys appear have formed near transition zone. In addition ringwoodite inferred stishovite, a nanometric been identified employing state-of-the-art analytical tools. Reconstitution now-exsolved precursor UH phases recognition subtle decompression microstructures produced during exhumation reflect earlier conditions. For example, Tibetan chromites containing exsolution lamellae coesite + diopside that original at  > 9–10 GPa depths >250–300 km. The phase most likely had Ca-ferrite or Ca-titanite structure; both are polymorphs chromite (at 2000 °C) would minimum pressures  > 12.5 20 GPa respectively. Some podiform host peridotites rare undoubted origin, zircon, feldspars, garnet, kyanite, andalusite, quartz, rutile; zircons possess much older U–Pb ages than time ophiolite formation. These mineral-bearing chromitite hosts evidently evolution prior extensional upwelling partial melting shallow form overlying complexes. new findings stable inclusion characteristics provide compelling evidence for profound underflow oceanic continental lithosphere, surface ‘organic’ carbon into lower mantle, ascent upwelling. Intensified study granulite-facies basement should allow better understanding geodynamics subduction cycling.