大陆碰撞造山带脱碳机制及其对古元古代深部碳循环的启示OA

Continental collisional orogens represent a critical component of Earth's deep carbon cycle,with their decarbonation processes exerting a profound influence on global carbon budgets and long-term climate evolution.In contrast to oceanic subduction zones,continental collision belts are characterized by higher geothermal gradients,more felsic(sialic)compositions,and weaker fluid activity.Their decarbonation mechanisms are dominated by metamorphic reaction-driven decarbonation and anatexis-induced carbon release.This contribution systematically reviews decarbonation mechanisms in continental collisional orogens,with a focus on thermodynamic modeling of Paleoproterozoic"hot"orogens(exemplified by the Khondalite Belt,North China Craton)to elucidate carbon cycling characteristics under early plate tectonic regimes.Modeling results reveal that high geothermal gradients promoted intense and rapid metamorphic decarbonation during the early prograde stage in Paleoproterozoic orogens,whereas Phanerozoic cold orogens experienced decarbonation predominantly during exhumation.Under high-temperature and fluid-present conditions,carbonate rocks may undergo partial melting(generating anatectic carbonatites).These carbonatitic melts are highly mobile,and their degassing during formation,ascent,and interaction with country rocks constitutes a significant pathway for carbon release.We propose that the widespread continental collisional orogeny and supercontinent assembly events in the late Paleoproterozoic,due to their elevated thermal regimes,may have triggered large-scale carbon emissions,profoundly influencing contemporary global carbon cycling and climate evolution.The associated carbon fluxes quantitative constraints are needed in future models.