THE DIVERSITY OF LATE NEOGENE SEDIMENTARY BASINS GENERATED BY WRENCH FAULTING IN THE EASTERN BETIC CORDILLERA, SE SPAIN

In this paper, we review the types of sedimentary basins which are generated by wrench faulting with particular reference to the Late Neogene Eastern Betic Shear Zone, a well-documented segment of the Trans-Alboran Shear Zone. The general characteristics of this wrench "corridor" are described, including the role of inherited structures. The diversity of basin types is emphasised, as is the coexistence of basins which developed under compressional or extensional regimes.
Pull-apart basins do not appear to be the most widespread type of basin in the Eastern Betic Shear Zone. Rather, compressional "groove-shaped synclines" which run parallel to master strike-slip faults (regardless of their orientation or direction of movement) are more typical structures. They are characterised by intense synsedimentary deformation and reworking of sediments, depositional processes being dominated by gravity flows. The basins are relatively short-lived and generally undergo structural inversion. Sedimentary basins also form in extensional areas, most significantly in the triangular zones which occupy the extensional quadrant of a pseudo- conjugate strike-slip fault system.
In the Eastern Betics, it appears that compressional basins are more efficient than extensional basins in terms of their subsidence and sedimentation rates, the thickness of the clastic fill, and the intensity of synsedimentary deformation. Compressional basins may therefore be the more favourable with respect to potential hydrocarbon accumulations.