Ksenia Igorevna Zatolokina

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 (X_CO2 = CO₂/(H₂O + CO₂) = 0.74–0.99) with elevated values (X_CO2 = 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 (X_CO2 = 0.74–0.84). Amphibolite-facies cordierites (Yenisei series) show significantly lower CO₂ contents (X_CO2 = 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.

The composition of volatile components of cordierite from the Muzkol metamorphic complex was studied using shock destruction with pyrolysis-free gas chromatography-mass spectrometry (GC-MS) with simultaneous IR and Raman spectroscopy. Applying the GC-MS procedure, the component relative concentrations (rel.%) and composition of different zones of cordierite crystals were determined. It was found that the substantially magnesian cordierite was formed with a predominantly aqueous-carbonic acid fluid (from 57.06 to 67.88 rel.% H₂O, from 24.29 to 32.95 rel.% CO₂). From the center towards the crystal periphery, the molar fraction of carbon dioxide (CO₂/(H₂O + CO₂)) decreases from 0.36 to 0.26, whereas the alkane/alkene ratio increases from 0.80 to 0.88. At least 11 homologous series of organic compounds among the identified volatile components, in addition to water and carbon dioxide, were determined, including oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, polycyclic aromatic hydrocarbons (PAHs)), as well as oxygen-containing (alcohols, esters, aldehydes, ketones, carboxylic acids) and heterocyclic (furans, dioxanes) organic compounds.

—The compositions of volatile components in cordierite, tourmaline, and quartz from pegmatites of the Kuhilal deposit were studied by pyrolysis-free gas chromatography–mass spectrometry (GC–MS), IR and Raman spectroscopy, and microthermometry, and their comparative analysis was performed. Capillary GC–MS was applied to determine the component composition and relative contents (rel.%) of volatiles from different zones of crystals and fractions of cordierite. It has been established that water and carbon dioxide prevail among them. Among hydrocarbons, aliphatic, cyclic, and oxygenated ones are predominant. Heterocyclic, nitrogenated, and sulfonated compounds have also been found. In tourmaline and quartz, volatile components are present in gas–liquid inclusions; in cordierites, they are localized both in structural cavities and in nonstructural positions.