A Geophysical Study of the Uncompaghre uplift, Colorado and Utah

CASILLAS, HECTOR A., and RANDY G. KELLER, University of Texas at El Paso, Department of Geological Sciences. El Paso, Texas 79768

    As part of the “Ancestral Rockies”, the Uncompaghre uplift is quite complex to understand geologically speaking since it is largely covered by sediments and there is limited subsurface information. The main deformation in the region began in the Pennsylvanian and continued through the Middle Triassic being recorded by facies changes and truncational unconformities. Tectonic activity along the uplift is now mostly covered by Mesozoic and Tertiary sediments. Any reconstruction of the geologic history of this complex fault-fold uplift must rely entirely on subsurface interpretations based on drill holes and geophysical data.

    The question targeted in this thesis is that since mountain belts are usually located along plate margins that generate compressional stresses that work against gravity and drive block uplift, why did the Ancestral Rocky Mountains formed in the middle of the North American plate, 1500 km away from any active plate boundary. Their intraplate setting along with their structural evolution is a mystery to be solved. An important key to explain this mystery is the application of a variety of geophysical data. By deciphering the structure and geological history of the uplift, the origin of the Ancestral Rocky Mountains will become clearer.

    Remote sensing, gravity, well logging, magnetic, and seismic geophysical approaches will be applied to the Uncompaghre uplift region. Gravity and magnetic models will be produced using new software tools being developed at UTEP.

    Geometric, radiometric and spatial enhancement applications will be applied to the Uncompaghre uplift LANDSAT and ASTER scenes using ENVI software. Although the main point of this study is to concentrate on the subsurface structure of the uplift, remote sensing imagery will aid in geographically controlling the geological feature extent of the region of interest. And so, seismic and well log data will explain the subsurface geological structures producing a complete geophysical study along the Uncompaghre uplift.