HR: 13:45h
AN: T53D-01 INVITED     [Abstracts]
TI: Detailed Fluid/Melt Structure Deduced from Geophysical Field Observations
AU: * Schilling, F R
EM: fsch@gfz-potsdam.de
AF: GFZ Potsdam, Department 4 Telegrafenberg, Potsdam, 14473 Germany
AB: Geophysical field observations point to the present existence of huge amount of melts in the crust below the Central Andes (e.g. Schilling & Partzsch, 2001). The Central Andes are an ideal place to study melt distributions in a continental crust due to the amount and quality of geophysical, geological, petrological, and geochemical studies within the framework of the Special Research Project 267, Deformation processes in the Andes, including seismic velocity and wave absorption studies, as well as electrical conductivity and gravity observations. Furthermore, laboratory studies and model calculations were performed in conjunction with the field measurements to study the effect of partial melts on the physical properties of rocks. The melt distribution/melt structure were optically determined in the laboratory on quenched samples. Laboratory experiments on the electrical conductivity and elastic properties of partially molten rocks are used in combination with melt structure observations to get a detailed insight into the dependence of physical properties on the melt structure. The interrelation of different properties allows to distinguish between melt isolated in pockets (magma chambers) and interconnected melt along grain boundaries or grain edges. The aim of this contribution is to use the interrelation of different physical properties to get a more detailed insight into the melt distribution of large areas, which have been inferred to be partially molten. The field observations are interpreted with respect to the laboratory experiments, while taking the scaling problem into account. The results deduced from the Andes will be compared to observations from the Tibetan Plateau. Schilling F.R., Partzsch G.M. (2001) Quantifying Partial Melt Portion in the Crust Beneath the Central Andes and the Tibetan Plateau, Physics and Chemistry of the Earth (A), 26, 239-246.
DE: 8450 Planetary volcanism (5480)
DE: 8100 TECTONOPHYSICS
DE: 8105 Continental margins and sedimentary basins
DE: 3600 MINERALOGY AND PETROLOGY (replaces
DE: 3900 MINERAL PHYSICS
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting