Integrated Studies of Basin Structure in the Southwest United States

G. Randy Keller
University of Texas at El Paso, El Paso, TX

Southwestern North America is an excellent place to study the structure and evolution of sedimentary basins via an integrated analysis based on gravity and magnetic data. The area contains extensive hydrocarbon resources and has experienced a complex Phanerozoic tectonic evolution. Precambrian and early Paleozoic structures have often influenced the development of many younger structures, but understanding the structural relationships requires innovative integrated analysis based on all available data. Throughout the southwest, the number of wells that have drilled completely through the Ellenberger Formation and equivalent units is relatively small. Also, many “basement” tests are questionable due to the many Tertiary intrusions present. There remain many unknowns, but it seems clear that significant thicknesses of prospective strata lie beneath the lower Paleozoic in many areas. Thus, there is a frontier defined by stratigraphic depth. In addition, younger structures such as those associated with the Ancestral Rocky Mountains have often been affected by older rift structures preserving significant thicknesses of Paleozoic strata. The formation of the Ancestral Rocky Mountains is an enigmatic and globally significant episode of intraplate deformation. Recent geophysical and drilling results are documenting the diversity large size of the structures associated with this orogeny. Finally, the Laramide orogeny and the formation of the Basin and Range/ Rio Grande rift are both complicating factors and exploration opportunities. Recent integrated studies have begun with gravity, magnetic, and regional geologic data and have progressed by using relatively scarce seismic and drilling data as constraints in modeling gravity and magnetic data. We will show results from several of these studies.