ABSTRACT
Transfer zones in extensional regions display a wide range of geometries from discrete fault zones to zones of broad warping. The classification of extensional fault displacement transfer zones developed in this paper includes three main criteria: (1) primary subdivision of transfer zones by relative attitude and direction of throw of the major faults (synthetic and conjugate); (2) secondary subdivision of conjugate transfer zones into transfer zones where the normal faults dip toward each other (convergent) and where the transfer zones occur between faults that dip away from each other (divergent); (3) the tertiary subdivision of conjugate relationships of transfer zones and secondary subdivision of synthetic transfer zones are by the fault terminations in plan view; fault tips approach, or they overlap, completely overlap (termed “collateral”), or are in line (termed “collinear”). A high abundance of overlapping transfer zones occur in the East African rift where extension is low and large-scale cross faults (prototransform faults?) are uncommon. Commonly, transfer zones in this region are relatively high areas with complex internal fault geometries flanked by deeps.
Transfer zones in rifts contain complex but somewhat predictable structural geometries that make them optimum locations for structural hydrocarbon traps. The classification presented herein can help define and delineate those zones and to some degree predict their internal structural geometry.
