Abstract:
Exploration for uranium-mineralized breccia pipes in northwestern Arizona, USA, has generated
interests for several years. These deposits contain high-grade uranium ore and by-products such
as Ag, Au, Cu, Pb, Zn, and V. The breccia pipes were formed from the collapse of the overlying
sedimentary strata into karst caverns developed in the Mississippian Redwall Limestone. The
breccia pipes are known to occur in clusters and are commonly observed along the cliffs of the
Grand Canyon and other near-by canyons. On undissected areas of northwestern Arizona part of
the Colorado Plateau, the pipes appear as circular features with concentrically inward dipping
beds. For most of the known deposits, hydrothermal alteration associated with the uranium-
mineralization is concealed under veneer of soil. In this study, digitally enhanced Landsat
Thematic Mapper (TM) images were used to identify more than 80% of previously known
orebodies as well as additional anomalies. In addition, digital image processing and integration
of datasets were used to develop exploration models from airborne electromagnetics (EM) ,
mangetics and very-low-frequency electromagnetics (VLF-EM) data collected over an area in
northwestern Arizona. One of the best models incorporated apparent resistivity and total
magnetic; the results of this model outlined 13 anomalous areas for further investigation.
