Physics
Scientific paper
Dec 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005geoji.163.1025f&link_type=abstract
Geophysical Journal International, Volume 163, Issue 3, pp. 1025-1038.
Physics
3
Scientific paper
Torsion oscillatory deformation experiments have been performed at high temperatures (600-1170°C) and over a wide range of low frequencies (20-2.10-3 Hz) on fine-grained gabbronorite samples from the Oman ophiolite in order to determine the shear wave attenuation as a function of temperature and melt fraction. The specimens have a small and uniform grain size (0.25-0.3 mm) and do not contain secondary, hydrated minerals. Measurements of internal friction (Q-1) were performed using a forced oscillatory torsion apparatus at small strains (~10-7), and with increasing small temperature steps to reduce thermal microcracking. The general dependence of Q-1 to frequency is Q-1~ω-α, where ω is the angular velocity of forced oscillations and α is an empirical exponent. Below the melting temperature (~1050°C), α has average values of ~0.15 at low frequency (<=0.5 Hz) and 0.06 at higher frequency. Above the melting temperature, α has average values of ~0.22 at low frequency and -0.02 at higher frequency. This frequency dependence of Q-1 is attributed to a viscoelastic behaviour due to the diffusion controlled grain boundary sliding, and partially to the squirt flow of the melt-phase wetting grain boundaries. The onset of melting is associated with a markedly higher Q-1 and a stronger dependence of Q-1 on temperature. The melt-related mechanical dissipation process could be a melt squirt flow. The characteristic frequency for the melt squirt flow is ωm~ 0.15-300 Hz when the melt pocket aspect ratio is ~10-3-10-2. Around the melting temperature the internal friction can be approximated by an experimental power law Q-1=A.[ω-1.d-1. exp(-Ea/RT)]α with α~ 0.08, A= 34.72s-αμm-α and Ea~ 873 kJmol-1.
Bagdassarov Nickolai S.
Fontaine Fabrice R.
Ildefonse Benoît
No associations
LandOfFree
Temperature dependence of shear wave attenuation in partially molten gabbronorite at seismic frequencies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Temperature dependence of shear wave attenuation in partially molten gabbronorite at seismic frequencies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature dependence of shear wave attenuation in partially molten gabbronorite at seismic frequencies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1432184