Earth Planets Space, Vol. 57 (No. 8), pp. 701-715, 2005
Mark E. Gettings and Mark W. Bultman
U.S. Geological Survey, 520 N. Park Ave., Tucson, AZ 85719, USA
(Received February 13, 2004; Revised February 14, 2005; Accepted February 15, 2005)
Some aquifers of the southwest Colorado Plateau, U.S.A., are deeply buried and overlain by several imper-meable units, and thus recharge to the aquifer is probably mainly by seepage down penetrative fracture systems. This purpose of this study was to develop a method to map the location of candidate deep penetrative fractures over a 120,000 km2 area using gravity and aeromagnetic anomaly data together with surficial fracture data. The resulting database constitutes a spatially registered estimate of recharge location. Candidate deep fractures were obtained by spatial correlation of horizontal gradient and analytic signal maxima of gravity and magnetic anoma-lies vertically with major surficial lineaments obtained from geologic, topographic, side-looking airborne radar, and satellite imagery. The maps define a sub-set of possible penetrative fractures because of limitations of data coverage and the analysis technique. The data and techniques employed do not yield any indication as to whether fractures are open or closed. Correlations were carried out using image processing software in such a way that every pixel on the resulting grids was coded to uniquely identify which datasets correlated. The technique cor-rectly identified known deep fracture systems and many new ones. Maps of the correlations also define in detail the tectonic fabrics of the southwestern Colorado Plateau.
Key words: Fracture recharge geospatial correlation potential fields tectonic fabric.