MAPPING THE EXTENT OF THE COOK CANYON TUFF IN THE SOUTHERN BLACK MOUNTAINS AND CERBAT MOUNTAINS OF ARIZONA VIA ADVANCED SPACEBORNE THERMAL EMISSION AND REFLECTION RADIOMETER (ASTER) IMAGERY

The 18.9 Ma Cook Canyon Tuff (CCT) (Lidzarski, 2014) is an enigmatic trachytic ignimbrite in the Northern Colorado River Extensional Corridor of the Basin and Range province of the United States (Pratt et al., 2014, Gaudio et al., 2003). In the Southern Black Mountains (SBM) and Cerbat Mountains (CM) of western Arizona, the CCT stratigraphically precedes the 18.8 Ma supereruption-produced Peach Spring Tuff (PST). The close age and spatial proximity of the CCT to the PST suggests that the CCT may offer insight into the magmatic activity that immediately precedes a supereruption. However, its geographic distribution – and thus its size and volume – is not well characterized. Here, we describe our attempts to define the extent of the CCT in the SBM and CM by distinguishing it from other local tuffs using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Specifically, we have used band math, spectral profile analysis, and supervised classification tools in ENVI image analysis software to create a map showing the extent of the CCT. To groundtruth the remote sensing data, we described stratigraphic sections and collected field samples from six locations in the SBM and CM which were analyzed petrographically and geochemically (Perry et al., 2015, and Scheland et al., 2015, GSA abs.). These locations include outcrops in Coyote Pass, Cook Canyon, Union Pass, Warm Springs, Yucca, and Yucca North, some of which were used as training sites for the supervised classification techniques employed in ENVI. The spectral profile of the CCT in general has similar absorptions and reflections as a typical felsic tuff as characterized in the ASTER spectral library (Baldridge et al., 2009). The primary characteristic which can distinguish the CCT from other local tuffs is a difference in slopes between band 3 and band 4, as well as band 4 and band 5. Our results show that the CCT extends over an area as far north and east as Kingman, AZ (~3900000 m N, ~769000 m E, UTM 11S), as far west as Union Pass (~726000 m E, UTM 11S), and as far south as Warm Springs (~3864000 m N, UTM 11S). Thus, the total area covered in the SBM is at least ~1,550 km². Our results suggest that the PST, which is at least 35,000 km² (Gaudio et al., 2003), was preceded by an eruption that was up to 20 times smaller in its extent.