Ultra-high pressure inclusion in Archean ophiolitic podiform chromitite in mélange block suggests deep subduction on early Earth

The discovery of ultrahigh pressure (UHP) minerals in orogenic belts has revolutionized our understanding subduction and the return flow previously deeply subducted material to Earth's surface as part cycling interaction crustal mantle systems. One class UHP is found inclusions peridotite-hosted podiform-chromite systems, within Phanerozoic ophiolites ophiolitic mélanges. Such have opened a window into processes recycling materials deep back through convection orogens. Here, we document first occurrence an mineral hosted podiform chromitite mélange from Neoarchean paired metamorphic belt Central (Taihang) Orogenic Belt, Northern China. Numerous rutile, apatite, dolomite, amphibole are interpreted be crustal-derived; they occur chromite grains 2.6–2.5 Ga now North China Craton formed by oceanic continental material. Microstructures phase relationships multi-phase inclusion TiO2(II), tremolite yield minimum P-T conditions 7.5 GPa at 1000 °C, indicating that host, including carbonates, were depths > 270 km, transferred overriding plate, returned 2.5 Ga. We suggest slab rollback forced upward flow, incorporating entities lower perhaps serpentinite diapirs, resulting adiabatic melting allowed trapped crystallizing high-Mg melts. Contrasting bulk moduli thermal contraction host protected P-induced back-reaction during exhumation. Together, these features show 1600 km long Belt emerging world’s well-documented style orogen, with classic tectonic zonation, mélanges, metamorphism, local evidence for conditions, foreland basins, late post magmatism. Applying null hypothesis, explain this high degree similarity invoking operation plate tectonics, least throughout length COB, geological comparison, other similar aged terrains globally. From infer modern-style tectonics was operating Neoarchean.