HR: 0800h
AN: T51C-0465    [Abstracts]
TI: Seismic Properties and Acoustic Emission of Olivine and Molten Basalt: A Laboratory Study
AU: * Burlini, L
EM: burlini@erdw.ethz.ch
AF: Geological Institute, ETH, Sonneggestrasse, 5, Zurich, 8092 Switzerland
AU: Vinciguerra, S
EM: sergio.vinciguerra@ct.infn.it
AF: Osservatorio Vesuviano-INGV, Via Diocleziano 328, Napoli, 80124 Italy
AU: Vinciguerra, S
EM: sergio.vinciguerra@ct.infn.it
AF: Dipartimento di Fisica e Astronomia,Universit… di Catania, Via S. Sofia, 64, Catania, 95123 Italy
AU: Meredith, P G
EM: p.meredith@ucl.ac.uk
AF: Department of Earth Sciences, University College London, Gower Street, London, WC1 6BT United Kingdom
AU: Zappone, A S
EM: zappone@seismo.ifg.ethz.ch
AF: CNR-IDPA, Via Botticelli, 23, Milano, 20133 Italy
AU: Di Toro, G
EM: giulio.ditoro@unipd.it
AF: Dipartimento di Geologia, Paleontologia e Geofisica; Universit… di Padova, Via Giotto 1, Padova, 35137 Italy
AB: Here, we present the first results of petrophysical investigations on the system olivine + MORB up to 1473K and 300MPa confining pressure using an internally-heated Paterson gas apparatus especially designed for the measurements of physical properties of rocks. Both Vp and acoustic emissions were measured during heating and cooling of cold pressed synthetic aggregate of both San Carlos olivine and MORB powder (in the latter case till complete melting). The same measurements were also made on a layered sample comprising an olivine-MORB-olivine sandwich. Vp was measured using the pulse transmission technique, with 1 MHz piezoelectric transducers mounted on the end of ceramic buffer rods. The buffer rods were calibrated using a single crystal of sapphire cut parallel to the c-axis. The acoustic emissions were recorded using the same transducers. A significant decrease of both velocity and of the amplitude of the seismic signal were observed during experiments involving MORB at temperatures above 1273 K. BSE imaged that melt from the MORB layer had intruded into the olivine matrix, even under hydrostatic conditions. Higher acoustic activity recorded after the melting onset, characterized by short durations and very low amplitudes, confirms the melt migration, and suggests a brittle intrusive mechanism such as hydrofracturing. Importantly, this provides a unique experimental insight into magma migration in the lithosphere and the mechanism of dyke emplacement. The results support the presence of a low but distinguishable seismic output during this process.
DE: 8434 Magma migration
DE: 8145 Physics of magma and magma bodies
DE: 5102 Acoustic properties
DE: 5104 Fracture and flow
DE: 3909 Elasticity and anelasticity
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting