EXPLORING THE EXTENT OF MIOCENE-AGED MAFIC ROCK UNITS IN THE BLACK MTS, AZ, USING SATELLITE IMAGERY

The 18.8 Ma Peach Springs Tuff (PST) is the product of a Miocene-aged supereruption that deposited >640 cubic kilometers (DRE) of material across SE California, SE Nevada, and NW Arizona. As part of a larger effort to further understand the processes associated with supereruptions, specifically processes leading up to a supereruption, we have performed a remote sensing study of units that pre-date the PST. We focus here on a mafic lava that crops out immediately below the PST in the Caliche Spring (~34.8° N, 114.2° W) and Warm Springs (~34.9° N, 114.3° W) areas in the southern extent of the Black Mountains of NW Arizona. This roughly 30 meter thick unit resides between the PST and the underlying Cook Canyon Tuff, a smaller-volume ignimbrite (Pratt et al., 2014 GSA abst).

Using Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) images with a mafic index of bands 12/13 (Pour and Hashim, 2012 Ore Geol Rev), we are able to pin point this mafic unit and collect its spectral signature. Image collected spectra show a slight absorption at 0.65 μm, a deeper absorption at 2.2 μm, and again at 2.3 μm.

This work represents the first attempt to describe this unit and its extent using a remotely sensed perspective. We intend to expand on our successful characterization of this mafic lava to map the extent of similar lavas underlying PST in remote areas of the southern Black Mountains. It has been suggested that intrusion of mafic magmas may have provided heat that was critical to production of the giant PST magma body and a triggering mechanism for the eruption (Pamukcu et al 2013 J Pet; Flansburg et al 2014 GSA abst). To test these hypotheses, ASTER-based remote sensing mapping will provide better constraints on the lateral extent and volume of the pre-eruption mafic lavas.