Abstract: A Natural Analog for the Structural Development of North Sea Rift Basins; The Canyonlands Graben of Southeast Utah

Bruce D. Trudgill, Joseph A. Cartwright

Good exposure of interlinked fault systems in the field is rare. The Canyonlands Graben of southeast Utah provide an excellent opportunity to examine detailed fault geometries and compare them with those observed in North Sea rift basins. All the major graben in the Canyonlands system consist of two or more en echelon elements, bounded by steep normal faults which are distinctly segmented in map view. Relay zones are defined as regions of fault overlap, characterized by well defined relay ramps, often rotated and extended in order to accommodate the ductile strain between overlapping fault segments. Relay ramps develop as ephemeral structures and the breakdown of ramps by breaching is part of the process of fault growth by segment linkage.

The evolution of the Canyonlands Graben system can be reconstructed by successively backstripping linkage of the growing fault segments. Variations in fault linkage through time have significantly affected sediment input paths into the graben. Such variations are compared to interpreted fault development patterns for selected North Sea rift basins. As well as affecting sediment input and distribution, the evolution of fault systems through time has critical implications for fluid migration paths and trap integrity of mapped prospects. The scale of the Canyonlands Graben is analogous to smaller North Sea fault systems and the observed field geometries have significant applications to the interpretation of seismic data in structurally complex areas, particularly the margins of rift basi s.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994