Fault reactivation and rift localization: Northeastern Gulf of Aden margin

[1] The Gulf of Aden and the Sheba spreading ridge ( Gulf of Aden) forms the southern boundary of the Arabian Plate. Its orientation ( 075 degrees E) and its kinematics ( about 030 degrees E divergence) are interpreted as the result of an oblique rifting. In this contribution, a field study in the northeastern Gulf of Aden allows us to confirm the Oligo-Miocene synrift directions of extension and to precise the normal fault network geometry. The synrift extensions are 020 degrees E and 160 degrees E ( possibly in this chronological order); the normal faults strike 070 degrees E, 090 degrees E, and 110 degrees E. The results show that some characteristics are consistent with oblique rifting analogue models, while some others are not. Especially, fault reactivation of Mesozoic structures is shown to have occurred significantly at the beginning and during rifting. These data are therefore compared to analogue models of oblique reactivation, and this comparison demonstrates that fault reactivation played a key role during the early stage of the Gulf of Aden rifting. Finally, scenarios of the lithospheric evolution during the eastern Gulf of Aden opening ( preexisting weaknesses in the lithosphere or not) are discussed to better constrain the deformation history of the northern margin. Especially, we show that rift localization processes may imply stress rotations through time.