Studying the forms of dissolution of hydrogen, carbon, nitrogen and oxygen volatiles in magmatic melts of the early earth's mantle by the methods of IR and Raman spectroscopy

Abstract

Citation: Kadik, A. A., V. V. Koltashev, E. B. Kryukova, V. G. Plotnichenko (2011), Studying the forms of dissolution of hydrogen, carbon, nitrogen and oxygen volatiles in magmatic melts of the early earth's mantle by the methods of IR and Raman spectroscopy, Vestn. Otd. nauk Zemle, 3, NZ6031, doi:10.2205/2011NZ000161. Experimental studies of the features of dissolution of Н, C, N, O volatiles in the melting products of the early Earth’s mantle are continued. As a model system we have chosen the aluminosilicate melt (albite NaAlSi3O8 80 wt. %) + metallic Fe phase (FeO 20 wt. %) + H+C+N with nitrogen addition (Si3N4 1, 3, 5, 7 wt. %) which at quenching the products of experiments provides НС-N-O-containing silicate glasses. The quenching was carried out at a high pressure 4 GPa, high temperature 1550 о С, and low values of the chemical oxygen potential (fugacity fO2) from -2 to -4 below the iron-wustite buffer equilibrium lgfO2 (IW). The investigation techniques were IR (infrared) micro spectroscopy and micro Raman. The IR absorption spectra (Fig. 1) were measured on a vacuum Fourier-transform FTIR spectrometer “Bruker IFS-113v” with an optical microscope “IR Microscope A590”, focusing the radiation passing through the investigated samples into a spot from 15 to 400 m in diameter. The Raman spectra measurements (Fig. 2) were provided on a Triple Raman spectrograph Т-64000 (Jobin Yvon) in which the exciting radiation from Ar + -laser was focused on a sample surface into a 2 m spot. The application of these techniques has allowed to establish the influence oxygen fugacity (fO2) on the ratio between the oxidized (H2O, OH - CO2, C=O, CO3 2- ) and reduced (H2, CH4, SiC, C-C) Н- and C-species in the melts, as well as O2, N2, N-O, C-N and others N-H complexes (NH3, NH4 + , NH2 - (≡Si-NH2), NH2 + (≡Si-O-NH2)) in a rather wide region of the redox state