Abstract
<jats:p>Relevance. Need to obtain factual data on the composition of volatiles in cordierite formation processes in Li-Be pegmatites. The newly obtained data can be used to adjust the holistic model of rare element deposit formation, taking into account the contribution of hydrocarbons. Aim. To determine the compositional features of the fluid preserved in structural cavities and channels in fluid inclusions of cordierites. Object. Cordierite-containing veins in the pegmatites of Buzheninov Bor, Murzinskoe pegmatite field, Middle Urals (Russia) and Dolní Bory (Czech Republic). Methods. The compositions of cordierite and sekaninaite were studied by the method of micro-X-ray spectral analysis. The forms of occurrence, structural positions and orientations of the molecules of fluid components in the aluminosilicate framework were determined by the methods of IR and Raman spectroscopy. The bulk composition of the fluid was analyzed by the method of non-pyrolysis gas chromatography-mass spectrometry with impact destruction of the sample. Results and conclusions. The gas chromatography-mass spectrometry method was used to determine the component composition and relative concentrations of volatiles localized in structural channels and cavities, fluid inclusions of natural cordierites. It was found that the fluids that formed the cordierite of the Middle Urals are essentially water-hydrocarbon with an admixture of carbon dioxide, nitrogen- and sulfur-containing compounds. They contain 87.5 rel. % of H2O, 10.5 rel. % of total hydrocarbons and 1.7 rel. % of CO2. Sekaninaite from the Dolní Bory pegmatites crystallized from a water-hydrocarbon-nitrogen fluid with an admixture of carbon dioxide, sulfur- and halogen-containing compounds: H2O – 68.8 rel. %, total hydrocarbons – 16.5 rel. %, nitrogenated compounds – 11.6 rel. %, CO2 – 2.6 rel. %. In total, 191 individual components were identified in the volatiles of the Ural cordierite, and 178 in sekaninaite. Identical halogenated fluid components 1‑chlorobutane (C4H9Cl) and 2,4‑dichlorobenzylamine (C6H5Cl2N) were recorded in the volatiles. The content of 1-chlorobutane in the Ural cordierite is 0.007, and in sekaninaite 1.669 rel. %, and 2,4-dichlorobenzylamine is 0.084 and 0.066 rel. %, respectively. The Ural cordierite is characterized by the presence of esters butyltrifluoroacetate (C6H9F3O2, 0.007 rel. %), and sekaninaite is characterized by the presence of 4‑(trifluoromethyl)-benzenamine (C7H6F3N, 0.035 rel. %) and 2-fluorobenzaldehyde (C7H5FO, 0.006 rel. %). Nitrogen monoxide (NO, 0.042 rel. %) was found for the first time in the composition of sekaninaite volatiles. For citation: Bulbak T.A., Tomilenko A.A., Zatolokina K.I., Shaparenko E.O. Fluid components in cordierites from the Middle Urals (Russia) and Dolní Bory (Czech Republic) pegmatites according to pyrolysis-free gas chromatography-mass spectrometry data. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 3, pp. 59–73. https://doi.org/10.18799/24131830/2026/3/5042</jats:p>