COMMINS, DEIRDRE C., T.H. Huxley School, Imperial College of Science, Technology and Medicine, London, UK

ABSTRACT: Fault-Growth and Drainage Development in the Canyonlands Grabens, Utah

Although the growth of faults has been shown to control fluvial patterns, the direct relationship between fault kinematics and the evolution of drainage systems is poorly understood at present. The Canyonlands Grabens of Utah consist of an excellently exposed normal fault array, which formed as a result of gravity sliding above salt. The growth and interaction of normal faults since the Pleistocene has had a marked influence on the ambient fluvial pattern. The antecedent drainage originally traversed the area in a Southeast to Northwest direction, from the Abajo Mountains to the Colorado River. Fault growth and linkage caused diversion and capture of the streams away from the topographic highs of the footwall faults and into the relative lows of the grabens, where thick sequences of sediment accumulate. The sediments often pond in the grabens to spill point, upon which deposition begins to fill the next appropriate topographic low. As faults continue to grow, streams may be completely beheaded, diverting the focus of deposition elsewhere.

The topography of the area has been examined in detail using both a Digital Elevation Model and field data. This data has been used to reconstruct the kinematic history of the fault array and sediment dispersal within the region. It is incorporated into an analogue model for the structural and sedimentological evolution of continental extensional regions, which play a vital role in the understanding of the hydrocarbon plays of these tectonic settings.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid