Seismic strain rates and distributed continental deformation in the northern Andes and three-dimensional seismotectonics of northwestern South America |
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| Authors: | Freddy Corredor |
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| Institution: | a Géosciences Azur, UMR 6526, Observatoire Océanologique, Université Pierre et Marie Curie, Villefranche s/mer 06235, France;b Department of Environmental and Earth Sciences, Sana'a University, Sana'a, Yemen |
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| Abstract: | Remote sensing and field studies of several extensional basins along the northern margin of the Gulf of Aden in Yemen show that Oligocene–Miocene syn-rift extension trends N20°E on average, in agreement with the E–W to N120°E strike of main rift-related normal faults, but oblique to the main trend of the Gulf (N70°E). These faults show a systematic reactivation under a 160°E extensional stress that we interpret also as syn-rift. The occurrence of these two successive phases of extension over more than 1000 km along the continental margin suggests a common origin linked to the rifting process. After discussing other possible mechanisms such as a change in plate motion, far-field effects of Arabia–Eurasia collision, and stress rotations in transfer zones, we present a working hypothesis that relates the 160°E extension to the westward propagation since about 20 Ma of the N70°E-trending, obliquely spreading, Gulf of Aden oceanic rift. The late 160°E extension, perpendicular to the direction of rift propagation, could result from crack-induced extension associated with the strain localization that characterises the rift-to-drift transition. |
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| Keywords: | Continental extension Rift propagation Strain localization Yemen Gulf of Aden |
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