A divergent (transtensional) wrench fault is one along which strike-slip deformation is accompanied by a component of extension. Faulting dominates the style and can initiate significant basin subsidence and sedimentation. The divergent wrench fault is distinguished from other wrench faults by predominantly normal separation on successive profiles, negative flower structures, and a different suite of associated structures. En echelon faults, most with normal separation, commonly flank the zone and exhibit evidence of external rotation. Associated folds are predominantly vertical drag and forced flexures parallel and adjacent to the wrench. Hydrocarbon traps can occur in fault slices within the principal strike-slip zone, at culminations of forced folds, in adjacent tilted fault blocks, and within less common en echelon folds.

The divergent wrench style may develop within transform systems where major strands splay or bend toward the orientation of associated normal faults (e.g., San Andreas fault zone in Mecca Hills). The style also occurs where wrench faults overstep in a divergent sense, or where regional plate motion is obliquely divergent to a linear fault (e.g., southern Dead Sea fault). Within extensional settings, divergent wrench faults may develop at graben doglegs or oversteps (e.g., between the Rhine and Bresse grabens) and may separate regions that experienced different magnitudes of extension (e.g., Andaman Sea area; Furnace Creek fault zone, California). The style has also been recognized in magmatic arcs and backarc settings (e.g., Lake Basin fault) near convergent plate boundaries and in in raplate basins (e.g., Cottage Grove fault system).

End_of_Article - Last_Page 484------------