Present-day Opening of the Natron Rift: Tectonic and Magmatic Processes at Work
Abstract
The young Natron basin (< 5 Ma), at the southern termination of the Eastern Branch of the East African Rift system, is an important locale to study the initial stage of continental rifting. It was the locus of a rarely observed tectono-magmatic event in July 2007, with slow slip on an intra-basin normal fault followed by a 10 km-long dike intrusion underneath the Gelai shield volcano. Here we report on a series of GPS observations over a 20-site network spanning the basin, measured repeatedly since 2013. We observe a long wavelength ( 200 km wide) extension with a horizontal rate of about 2 mm/yr, consistent with recentlty published regional kinematic models, and a velocity gradient centered on the west-bounding fault of the Natron basin. Initial models show that the data is best fit by a normal fault dipping 60 degrees to the east and slipping at a rate of 6 mm/yr. Superimposed on this long wavelength extension, we observe a smaller scale ( 30 km wide) extensional signal in the middle of the basin, roughly coincident with the location of the Gelai volcano, which was the locale of the 2007 seismic-magmatic crisis. We investigate the relative importance of tectonic faulting, post-diking relaxation following the 2007 intrusion (as observed for instance in Afar or Iceland after similar events), and melt recharge of the intra-basin magmatic system in present-day extension across this young segment of the East African Rift.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.T51B0451C
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8109 Continental tectonics: extensional;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS