Channelized CO2-Rich Fluid Activity along a Subduction Interface in the Paleoproterozoic Wutai Complex, North China Craton

Greenschist facies metabasite (chlorite schist) and metasediments (banded iron formation (BIF)) in the Wutai Complex, North China Craton recorded extensive fluid activities during subduction-related metamorphism. The pervasive dolomitization chlorite schist significant dolomite enrichment at BIF–chlorite interface support existence of highly channelized updip transportation CO2-rich hydrothermal fluids. Xenotime from has U concentrations 39–254 ppm Th 121–2367 ppm, with U/Th ratios 0.11–0.62, which is typical xenotime precipitated circulating SHRIMP U–Th–Pb dating determines a activity age 1.85 ± 0.07 Ga. metasomatic ?13CV-PDB ?4.17‰ to ?3.10‰, significantly lower than that carbonates greenschists, but similar originated Rayleigh fractionating decarbonation amphibolite metamorphism along regional geotherm (~15 °C/km) Complex. ?18OV-SMOW values (12.08–13.85‰) can also correspond this process, considering contribution dehydration. Based on phase equilibrium modelling, we ascertained was rich CO2, alkalis, silica, X(CO2) range 0.24–0.28. All these constraints suggest sediment–basite warm Paleoproterozoic subduction zone, allowed migration sequestration volatiles (especially carbon species) beneath forearc.