MATOS, RENATO, Petrobras, Natal-Rn, Brazil

ABSTRACT: Hangingwall Deformation by Extension Along Listric Normal Faults: A Numerical Solution

Hangingwall deformation, simulated through a forward modeling technique, offer new insight into hangingwall geometry, basically controlled by fault geometry and sense of internal shear. The true amount of horizontal extension and sense of inclined shear are estimated based on both rollover and fault geometry. Antithetic shear is likely to occur near steeply dipping normal faults, whereas near vertical and synthetic shear seems to dominate near low angle listric normal faults. Strain compatibility seams to be the key link between fault geometry and sense of internal shear (global simple shear). This geometrical model indicates that deformation near high angle listric normal faults may be dominated by bed-length extension (under near-vertical simple shear), whereas flexural slip is pred cted to dominate the deformational process for low angle normal listric faults, when deformed under synthetic simple shear. Arrays of steeply dipping listric normal faults may develop domino-like structures that may lead to erroneous estimates of extension if domino-style deformation on planar faults is assumed. The model successfully describes the overall geometry of half-graben type basins, and indicates an important link between fault geometry and sense of shear within the hangingwall of listric normal faults.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.