New Concepts from Experimental Models of Strike-slip Tectonics

Pascal D. Richard and Mike A. Naylor

This paper provides a retrospective view of scaled sandbox models of strike-slip faulting, which were carried out over the past 15 years at KSEPL (Shell Research). We present a variety of models which were firstly validated against structures mapped using wells and good quality seismic data, and could then be used to assist seismic interpretations in areas of poor data quality. The models presented have often contributed to a better understanding of regional tectonics, and have led to better definition of structural hydrocarbon traps.

In pure strike-slip, the Riedel shear geometry is shown to depend on the initial stress state, interference of parallel basement faults and horizontal layering of the overburden. Above two parallel basement faults, a single wide or two separate fault zones may be mapped, depending on the depth of observation. In a heterogeneous layered sequence, upwards branching of Riedel shears occurs at layer interfaces.

In oblique-slip faulting, the sense of vertical displacement and the geometry of the fault pattern are indicative of the tectonic regime. The degree of obliquity of the fault strike can be related to the ratio of dip-slip to strike-slip movement.

In the case of relay structures, the ratio of the length of basement-fault offset to the thickness of the overburden controls the geometry of the fault pattern.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California