HR: 0800h
AN: V31A-1402    [Abstracts]
TI: Hydrothermal Diamond Anvil Cell Investigations Into the Alumina-Silica-Water System up to 1073 K and 4 GPa
AU: * Davis, M K
EM: mkdavis@umich.edu
AF: University of Michigan, 2534 C.C. Little Building, Ann Arbor, MI 48109 United States
AU: Stixrude, L P
EM: stixrude@umich.edu
AF: University of Michigan, 2534 C.C. Little Building, Ann Arbor, MI 48109 United States
AB: Understanding fluid chemistry in the subduction zone environment is key to unraveling the details of element transport from the slab to the surface. Solubility of different mineral assemblages in predominantly water-rich fluid along with pressure and temperature conditions control the chemical structure of the aqueous fluid and govern the transport opportunities for various chemical components away from the subducting slab. In-situ Raman experiments were performed in the alumina-silica-water system in an externally heated Bassett-type hydrothermal diamond anvil cell in the Department of Geological Sciences at the University of Michigan. Natural quartz samples (from the Owl Creek Mountains, Wyoming) were used as the silica source and synthetic ruby was used for the alumina source. Temperatures inside the diamond cell were monitored using type-K thermocouples wrapped around the diamonds and the pressure calibrated by the Raman shift of diamond or quartz or the fluorescence of ruby depending on conditions. Raman measurements of the aluminosilicate fluid show the presence of multiple alumina, silica, and mixed species. As predicted by calculations an aluminosilicate specie possibly of the form (HO)$_{3}$SiOAl(OH)$_{3}$$^{2-}$ as well as the silica monomer and dimer specie were observed in the aluminosilicate fluid. There also appeared to be at least one hydrous alumina specie based on the presence of a Raman peaks at 228 cm$^{-1}$, 339 cm$^{-1}$ and 970 cm$^{-1}$ in the fluid and a comparative analysis between Raman peaks in aqueous fluid in the silica-water, alumina-water, and alumina-silica-water systems. Solid phases formed during experiments (diaspore, kyanite) were confirmed with Raman spectroscopy.
DE: 8424 Hydrothermal systems (8135)
DE: 3694 Instruments and techniques
DE: 3929 NMR, Mossbauer spectroscopy, and other magnetic techniques
DE: 3934 Optical, infrared, and Raman spectroscopy
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting