Water in the structure of minerals from mantle peridotites as controlled bythermal and redox conditions in the upper mantle

Abstract

Hydrous species and the amount of water (OH -ions and crystal hydrate H 2 O) in structures of nominally anhydrous rock-forming minerals (olivine, ortho-and clinopyroxenes) were studied with Fourier spectroscopy in peridotite nodules (19 samples) from Cenozoic alkali basalts of the Baikal-Mongolia region (Dariganga Plateau, Taryat Depression, and Vitim Plateau). Single-crystal samples oriented relative to the crystallographic axes of minerals were examined with an FTIR spectrometer equipped with an IR microscope at the points of platelets free from fluid inclusions. FTIR spectra were measured in regions of stretching vibrations of OH -and H 2 O (3800-3000 cm -1 ) and deformation vibrations of H 2 O (1850-1450 cm -1 ). The water content in mineral structures was determined from integral intensities. To estimate the conditions of entrapment and loss of structural water in minerals, their chemical composition, including Fe 2+ and Fe 3+ contents, was determined with an electron microprobe analysis and Mössbauer spectroscopy. The bulk chemical composition of some nodules was determined with XRF and ICP MS. The total water content (OH -+ H 2 O) varies from 150 to 1140 ppm in olivines, from 45 to 870 ppm in clinopyroxenes, and from 40 to 1100 ppm in orthopyroxenes. Both water species in the mineral structures are retained down to a depth of 150-160 km in wide temperature and pressure ranges (1100-1500 ° C, 32-47 kbar) at the oxygen fugacity of -1.4 to -0.1 log units relative to that of the quartz-fayalite-magnetite buffer.

Effect of alcohols additives on hydrothermal formation of magnesium hydroxide sulfate hydrate whiskers

“…In order to determine the effect of organic alcohol on MHSH whiskers growth process, the Fourier Transform Infrared Spectrum (FT‐IR) was used to measure the absorption of products obtained under different conditions, respectively, as presented in figure . The strong infrared absorptions at 598 cm −1 , 639 cm −1 , 1117 cm −1 correspond to the distortion of the SO 4 2− stretching vibration , 817 cm −1 corresponds to the coordinating bond between H 2 O and Mg 2+ , the peaks at 1662 cm −1 and 1629 cm −1 are assigned to the H‐O‐H bending vibration , 3662 cm −1 , 3612 cm −1 , 3549 cm −1 and 3416 cm −1 are attributed to the OH − , H 2 O, hydrogen‐bonded association and ‐OH stretching vibration of the MHSH whiskers, respectively. In figure b and c, the strong absorption bands located at 1550 cm −1 and 1482 cm −1 are characteristic of the CH 2 stretching and scissoring vibrations modes .…”

Mixed oxide-polyaniline composite-coated woven cotton fabrics for the visible light catalyzed degradation of hazardous organic pollutants

“…The band C-N is observed at 1225 cm -1 and C-H stretching vibrations of benzene ring were pointed at 1030, 847 and 697 cm -1 (Tanwar and Mandal, 2019). Stretching vibration -C-S is manifested by an IR signal at which is attributed to HCO 3 derived from CO 2 dissolved in water (Babushkina, Nikitina, Goncharov and Ponomareva, 2009;Garand et al, 2009). These spectra reflect the total mineralization of MO under visible light.…”

The Dynamic Structural-Material Complexes of the Earth’s Crust

“…It volume of the seas, oceans, river network, and part of the atmosphere and lithosphere in the free state fills. Water binds as part of mineral associations [6] or is released during their physicochemical transformations [64], creating mineral waters, brines, and in the depths of magma chambers forming [90]. Water participates in the circulation of the Earth's crust and lithosphere [39], and is a part of the general dynamic process that creates hydrogeological conditions for its occurrence [150].…”