Controls on the geometry of transfer zones in the Suez Rift and NW Red Sea: Implications for the structural geometry of rift systems

Abstract

Two main types of transfer zones are mapped in the Suez rift and the northwestern Red Sea. These are transfer zones between individual faults (fault-to-fault transfer zones [F-F TZ]) and transfer zones between half grabens with different fault domains (half graben–to–half graben transfer zones [H-H TZ]). Relay ramps and linkingtransfer faults are two main recognized types of F-F TZ. Different varieties of these F-F TZ have the form of en echelon fault belts with single or mixed polarity, tilted fault blocks at rift offsets, and zigzag fault arrays at major fault or rift jumps. Relay ramps transfer throw between overlappingnormal faults of the same polarity. Linkingtransfer faults join normal faults that have the same polarity with no overlappingseg ments, leading to a characteristic zigzag pattern. If the linked faults are listric, local anticlines and synclines develop at the corners of the zigzag fault array. Three H-H TZ in the Suez rift and northwest Red Sea show the effect of prerift structures (both faults and major folds) on the location, orientation, and style of deformation of the transfer zones of continental rifts. The widest one of these three H-H TZ (40–60 km) has a broad antiformal structure lyingbetween the overlapping ends of the listric faults boundingthe two linked half grabens and is deformed by dip-slip normal faults of opposite polarity. The other two H-H TZ reactivate prerift faults by strike-slip faultingdue to the angular relationship between these faults and the direction of extension in the rift.