Spectral Variation Across the Mono-Inyo Craters Chain, Weathering of a Young Volcanic System.

Abstract:

As part of the Hyperspectral Infrared Imager (HYSPIRI) preparation mission, the Airborne Visual Infrared Imaging Spectrometer (AVIRIS) has over flown the Mono-Inyo Craters chain located in Mono County, California to study the geothermal potential of the area. Data was taken at a spatial scale of 15m, similar to that of the highest resolution Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data. The Mono-Inyo Craters is a geologically young volcanic chain of 40 eruptive events, with the oldest eruptions dating to 40 Ka and the latest 200 years ago. Today 23 craters show exposure on the surface and vary from a more rhyolitic composition to a more basaltic composition in the north. This data shows spectral variability in the 1.0μm and 2.21μm absorption bands between volcanic centers. The 1.0μm absorption is attributed to iron and iron oxides and the 2.21μm to the Si-OH stretch likely due to the opalization of silica rich of volcanic materials. Such variation can be attributed to weathering of the exposed surface material within each crater. Older volcanic centers show a much deeper 2.21μm than younger volcanic centers. One exception to this is a volcanic dome known as the South Coulee. South Coulee is the location of a pumice mine that has exposed a fresh surface that has little to no weathering, and therefore a smaller 2.21μm band. We will show a correlation between crater exposure age and the 2.21μm band depth. On Mars weathering will take place at a slower pace, due to less water, but with much longer timescales such differences could still exist and be used to determine relative weathering and exposure ages of surfaces.