Rift Basin Styles/AAPG

Structural Styles of Rift Basins

Abstract--Structural geometries of rift basins vary significantly, depending on the mechanical behavior of prerift and synrift packages, tectonic activity before and after rifting, and obliquity of rifting. The following rift-basin classification is based on these factors. Type 1 basins (e.g., southern Suez rift; Jeanne d’Arc basin, SE Canada) have salt or thick shale in the prerift or synrift packages. They are characterized by forced folds above basement-involved normal faults, diapiric structures, and detached normal faults and associated fault-bend folds. In Type 2 basins (e.g., Fundy basin, SE Canada; Jeanne d’Arc basin), one or more major contractional events preceded rifting. Many of the normal faults in Type 2 basins are reactivated basement-involved thrust faults. These faults are commonly low angle and have large displacements. In Type 3 basins (e.g., Fundy basin; Vøring basin, offshore Norway; Exmouth basin, NW Australia), one or more contractional events followed rifting. These inverted rift basins are affected by late-formed contractional structures including normal faults reactivated as reverse faults, newly formed reverse faults, and contractional fault-bend and fault-propagation folds. Type 4 basins (e.g., Dampier basin, NW Australia) are produced by oblique rifting. They are characterized by faults with strike-slip, normal, and oblique-slip displacement and with multiple trends (i.e., parallel and oblique to the rift trend). Rift-basin type strongly affects petroleum potential. The timing and geometry of potential structural traps differ for the rift-basin types. Also, the distinct structural geometries in the rift-basin types influences depositional patterns and, thus, the distribution of potential reservoir and source rocks.

Go back to list of publications