Remote sensing applied to the exploration for uranium-mineralized breccia pipes in northwestern Arizona
Abstract
The currently depressed uranium market makes high-grade uranium deposits the only economically viable and attractive exploration target. In the United States, exploration for uranium-mineralized breccia pipes in northwestern Arizona has been active because of the high-grade ore they contain, which may also include such by-products as Ag, Au, Cu, Pb, Zn and V. These breccia pipes were formed from the collapse of the overlying sedimentary strata into karst caverns developed in the Mississippian Redwall Limestone; mineralization occurred between 200 and 220 m.y. ago as determined previously by U-Pb isotopic analyses. Spectroscopic and statistical analyses of field, laboratory, and digital Landsat Thermatic Mapper (TM) data were carried out to determine the fundamental spectral and mineralogical differences between samples on the surface of breccia pipes and their background areas. Spectroscopic and XRD mineralogical studies clearly demonstrate that hydrothermally altered rocks associated with mineralized breccia pipes are distinguished from the surrounding rocks by the Fe$\sp{3+}$, hydroxyl, and carbonate minerals content. These minerals are sensed by TM bands 1,3, and 7. Discriminant analyses of field, laboratory, and Landsat digital TM data indicates that 64-80% of the samples collected on the surfaces of breccia pipes and their immediately surrounding areas were correctly classified; however, the classification of some previously known breccia pipes not used in the discriminant analysis was not encouraging. Digitally enhanced TM images printed at the scale of 1:100,000 resulted in the recognition of more than 80% of previously known orebodies as well as additional anomalies identified in the study areas. Digital image processing techniques were applied to airborne geophysical data consisting of apparent resistivity, total-field magnetics, derived overburden thickness, and very low-frequency electromagnetics (VLF-EM) to evaluate the utility of the data sets for breccia pipe exploration. One of the most promising models incorporated apparent resistivity and total field magnetics. The results of this model outlined 13 anomalies representing 12% of the survey area. The processing and critical analysis of the geophysical data is apparently the most promising approach to breccia pipe exploration in this study.
Subject Area
Geology|Remote sensing
Recommended Citation
Kwarteng, Andrews Mensah Yaw, "Remote sensing applied to the exploration for uranium-mineralized breccia pipes in northwestern Arizona" (1988). ETD Collection for University of Texas, El Paso. AAI8911141.
https://scholarworks.utep.edu/dissertations/AAI8911141