Fluid Components in Cordierites from Granulite- and Amphibolite-Facies Rocks of the Aldan Shield and Yenisei Ridge, Russia: Evidence from Pyrolysis-Free GC-MS, Raman, and IR Spectroscopy

This study provides the first comprehensive characterization of fluid components in cordierites from both moderate- to high-pressure granulite facies of the Aldan Shield (Sutam and Nimnyr blocks), and granulite–amphibolite facies of the Yenisei Ridge (Kan and Yenisei series of the Angara–Kan complex), Russia, using integrated infrared and Raman spectroscopy coupled with pyrolysis-free gas chromatography–mass spectrometry (GC-MS). Granulite-facies cordierites record CO2-dominated fluids (XCO2 = CO2/(H2O + CO2) = 0.74–0.99) with elevated values (XCO2 = 0.89–0.99) in high-pressure, high-temperature (high-P-T) samples from the Sutam block and Kan series compared to moderate-P-T samples from the Nimnyr block (XCO2 = 0.74–0.84). Amphibolite-facies cordierites (Yenisei series) show significantly lower CO2 contents (XCO2 = 0.51–0.57) and higher H2O concentrations relative to high-pressure granulites. Critically, we report the first identification in cordierites of at least 12 homologous series of organic compounds and nitrogenated, sulfonated, and halogenated compounds. These results provide new constraints on fluid behavior across metamorphic facies transitions.