The ‘Austrian Event’ of the Afro-Arabian Plate and its Influence upon Cretaceous Petroleum Systems
The intra-Aptian ‘Austrian Event’ is widely recognized as a significant 2nd order sequence boundary across the Afro-Arabian plate. The complex stratigraphic character of the boundary is still only variably constrained because of ambiguous biostratigraphic control and late erosional unroofing, which stripped away much of the earlier Cretaceous cover. However, locally better preserved sections highlight a number of synchronous or near synchronous events which appear to correlate with initiation of oceanic spreading in the central South Atlantic (~ 119 Ma), cessation of spreading in the Somalia Basin and Mozambique Channel ( <121 Ma) and opening of the Ionian Basin to the north, together suggesting a major change in the intra-plate stress field perhaps driven by a change in mantle convection.
The event has had a variable but sometimes very pronounced influence upon Cretaceous petroleum systems across
the region ranging from:
(1) formation of structural (Hassi Toureg Axis & Illizi Basin, Algeria) and stratigraphic traps (Lekwair Arch, Oman).
(2) deposition of post-unconformity sandstone reservoirs (Euphrates Graben/eastern Syria, southern Iraq, coastal Tanzania, Gabon onshore),
(3) and post-unconformity migration conduits (Sirt Basin/Libya, South Atlantic margin),
(4)uplift and exhumation, terminating generation and charge from underlying source rocks (Libya/Murzuq Basin). reflecting both the tectonic adjustment directly responsible for the event itself and the subsidence and transgression which followed.
AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013