Structural Styles and Deformation in the Levant Basin Offshore Lebanon: New Insights from 3D Seismic Data

Ramadan Ghalayini, Catherine Homberg, Jean-Marc Daniel, and Fadi Nader

The Levant basin has been affected by several important tectonic events. Analysis of 3D seismic dataset covering 1600 km² offshore Lebanon indicates the presence of different structural patterns overprinting each others. During geologic times, reactivation of earlier structures has played a major role in creating structural traps for prospective petroleum plays.

In the investigated part of the basin, structural lineaments observed at the interpreted Upper Cretaceous horizon are aligned with or parallel to onshore structures. Younger deformations, consisting mostly of large faults, normal, reverse and strike-slip, appear to be linked with these lineaments. Some faults are affecting the sedimentation by creating thickness variations and local unconformities. They also form a variety of structural traps, especially in the complex deformation zone near the margin.

The Miocene sequence shows a number of NE-SW trending anticlines with well-mapped closures and tilted fault blocks. The anticlines are crosscut by NW-SE conjugate faults, suggesting that they were folded earlier. The extensive NW-SE closely spaced normal faults have an average dip of 45° and form numerous fault families with more or less evolved linkages. They create an extensive array of rotated fault blocks that might be considered as potential petroleum traps sealed by the overlying Messinian evaporites on top. Most of these faults are detached on a highly compacted fine-grained sequence suggested to be the Eocene. Their apparent polyphase timing, ongoing activity and well defined orientation suggest that they are linked to a basin wide tectonic event or related to Late Miocene/Pliocene deformation onshore.

The Pliocene sequence (overlying the Messinian evaporites) is characterized by conspicuous NE-SW closely spaced tight folds, creating a multitude of anticlinal traps with 4-way dip closures. A late Pliocene unit is deposited unconformably over the Early Pliocene, showing onlap and evidence of a decrease in shortening starting the Mid- Pliocene.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013