Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
AGU Fall Meeting, San Francisco, California, December 5–9, 2005
Integration of Hyperspectral Data with Airborne
The Franklin Mountains of west Texas contain world-class Ordovician paleocave system exposures. The units of interest are the El Paso Group (Lower Ordovician) and the Montoya Group (Upper Ordovician) which straddle a continent-wide second order supersequence and a 33 million year unconformity. Recent mapping of this outcrop system integrated traditional field mapping methods with AVIRIS (Visible Infrared Imaging Spectrometer), airborne and ground-based lidar-generated terrain models which revealed spectral patterns that allow us to delineate the calcite-dolomite transitions in three dimensions. These mineralogical variances are proposed to be linked to collapse brecciation associated with paleocave-fill deposits. This study area is important both as a hydrocarbon and water resource perspective as an end member fractured reservoir analog. The study area is characterized by excellent midlatitude illumination and very good outcrop exposure in steep and varied topography. Preliminary studies using a full-range portable spectroradiometer (400 to 2,500 nanometers) show that a variety of calcite- and dolomite-rich rock types can be differentiated using hyperspectral reflectance spectra. Atmospherically corrected airborne hyperspectral AVIRIS imagery was analyzed over the study area to differentiate lithologies at 20 meter spectral resolution. The analysis of these data show clear calcite-dolomite transitions associated with undisturbed host rock to paleocave collapse facies. This research introduces a unique method of field mapping through data integration at the ten square kilometer scale that is applicable to virtually any field area and is ideal for areas of difficult or restricted access.