Physics – Geophysics
Scientific paper
Nov 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009georl..3621308n&link_type=abstract
Geophysical Research Letters, Volume 36, Issue 21, CiteID L21308
Physics
Geophysics
6
Tectonophysics: Continental Tectonics: Extensional (0905), Tectonophysics: Rheology: Crust And Lithosphere (8031), Geodesy And Gravity: Transient Deformation (6924, 7230, 7240), Marine Geology And Geophysics: Midocean Ridge Processes, Tectonophysics: Tectonics And Magmatism
Scientific paper
Crustal accretion at divergent plate boundaries typically occurs via the periodic intrusion of dikes, but their emplacement and the associated deformation are rarely observed. The few existing observations at subaerial rifts show that these diking events are followed by a decadal-scale period with extension rates faster than the secular divergent plate motion. This transient accelerated deformation has been explained by continued subsurface magma injection or by relaxation, in the viscoelastic mantle, of the stress changes imparted by dike opening. For the first time, GPS measurements were collected within a few months of a rifting event at a major plate boundary, the September 2005, 60 km-long dike intrusion in the Dabbahu segment, Afar, Ethiopia. Extension rates for the first 3 years greatly exceed the plate motion (Nubia-Arabia) secular divergence rate, even at sites located more than 60 km from the rift axis. Here we show that these observations are consistent with stress relaxation in a viscoelastic upper mantle with a viscosity of about 5 × 1018 Pa·s overlain by a 12-14 km-thick elastic crust. The alternative model of continued diking requires continuous opening well below the Moho and is therefore unlikely. Instead, magma injection in Afar since June 2006 has taken the form of smaller discrete diking events, tapping into a mid-crustal melt reservoir under the segment center.
Bennati Laura
Buck Roger W.
Calais Eric
Hamling Ian J.
Lewi Elias
No associations
LandOfFree
Post-rifting relaxation in the Afar region, Ethiopia 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 Post-rifting relaxation in the Afar region, Ethiopia, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Post-rifting relaxation in the Afar region, Ethiopia will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1264693