Strike-Slip Salt Tectonic Structures Associated with Basement-Involved Faults: Analogies between the Frade Field and Surrounding Region in the Campos Basin, Offshore Brazil and the Zagros Fold-and-Thrust Belt, Iran

Salt tectonics plays a fundamental role in the development of salt-bearing basins, deforming the post-salt sedimentary package and diffusing the deformational forces originating from the basement to the post-salt section. The resulting deformation can form of a variety of extensional and contractional structures, including strike-slip zones. Salt tectonic related formation of strike-slip features is an under-researched topic that still relies heavily on kinematic models or rift basin studies, many of which do not involve salt layers. This work integrates seismic identification of salt structures controlled by strike-slip fault zones in the Campos Basin, Brazil with comparisons of field geology structure maps in the Zagros region, Iran, and some physical model data. The Frade Field Diapir provides a unique example of a salt structure associated with strike-slip fault zones and hydrocarbon accumulations. The transcurrent motion possibly resulted from basement-involved fault reactivations after salt deposition. Seismic data (2D and 3D) constrained by borehole data was interpreted in the central-north region of the Campos Basin to characterize the differential movements that affected the salt layer and its immediate overburden deposits. Geophysical maps indicate the salt structures are associated with basement highs where post-salt reactivation of the rift faults is observed. Possible basement coupling controls the thin-skinned transcurrent movement that locally affected reactions of overburden blocks and were investigated for the generation of the post-salt structures. The comparison results support the interpretation of transcurrent zones and other differently scaled deformation processes involving basement movements, leading to an original interpretation for the central-north Campos Basin. We conclude that the geomorphology of some diapirs and anticlinal structures in the Frade Field area and Zagros region show evidence of basement-involved strike-slip deformation affecting the salt layer and its overburden. This interpretation improves understanding for petroleum system exploration in salt basins associated with strike-slip movement.