Print this pageAbstract: Physical Modeling of an Irregular Strike-Slip Fault System and Similarities to the South American-Caribbean Plate Boundary
Jagiello, Keith and Jim Hornbeck - Amoco Exploration & Production Company
The boundary between the Caribbean and South American Plate is a right-lateral strike-slip fault system. Deformation to the south of this boundary in the Venezuelan Coastal Ranges, the Serrania Interior and Furrial Trend and Trinidad can generally be described by strain partitioning whereby thrust faults are bounded by large right-lateral strike-slip faults (Urica, San Francisco, Los Bajos). In order to simulate deformation in this region, a physical model was constructed of a rigid indentor being pushed through a claycake in a right-lateral strike-slip sense. The indentor has a right step confining bend.
Upon initiation of deformation, a thrusted anticline formed adjacent to the confining bend with a small right-lateral component of slip. As deformation progressed, thrusts continued to form in sequence with reverse dip slip primarily limited to the foremost thrust, although uplift of previous thrusts and subsequent deformation occurred adjacent to the edge of the confining bend as it moves forward.
As the rigid indentor moves, previously thrusted terrain is translated by right-lateral strike slip tear faults originating as reidel shears at the edge of the confining bend. These tear faults only cut the hanging wall thrusts and do not appear to cut the undeformed footwall. In addition, they are more numerous and more closely spaced adjacent to the indentor.
Material in the immediate vicinity of the confining bend is rotated as ductile clay moves around the edge of the confining bend. Material farther away rotates, very little since deformation is primarily accomplished by strain partitioning into thrusting and right-lateral translation. A component of right-lateral oblique motion occurs on the thrusts, but is relatively minor.
AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil