--> Abstract: Extensional Basins in a Forearc Setting: Betic and Rif Cordilleras (Western Mediterranean), by J. F. Flinch and A. W. Bally; #91012 (1992).

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ABSTRACT: Extensional Basins in a Forearc Setting: Betic and Rif Cordilleras (Western Mediterranean)

FLINCH, J. F., and A. W. BALLY, Rice University, Houston, TX

The Betic Cordillera in Southern Spain and the Rif Cordillera in Northern Morocco constitute part of an arcuate fold and thrust belt, known as the Gibraltar arc, which is the western end of the Alpine-Himalayan system. The frontal part of the Gibraltar arc is an accretionary complex of Miocene-Pliocene age. Based on interpretation of seismic reflection profiles, boreholes, and surface data, its structure is characterized by normal and thrust faults. The older structures are normal and thrust faults, sometimes connected into the same decollement level, and parallel to the direction of the arc. These structures are overprinted by extensional basins trending perpendicular to the arc. Positive structural inversions can be generated as a result of space problems caused by east-west extensi n or due to the outward migration of the deformation in the accretionary complex. Slumping in the front of the wedge postdates the previous structures.

The age of the materials involved in the accretionary wedge, the timing of the structures, as well as the stratigraphic signature of

sediments located on top of the wedge define the evolution of the arc. This structural development led to different, genetically linked extensional and compressional basins, and resulted in a great number of potential hydrocarbon traps. The compressional deformation in the accretionary complex is coeval with the backarc extension (Alboran sea), and it can be interpreted in terms of extensional collapse of the orogenic belt.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)