SOIL SURFACE CHARACTERIZATION OF THE MANCOS SHALE WITHIN THE GUNNISON GORGE NATIONAL CONSERVATION AREA USING MASTER DATA

Mancos Shale soil surfaces are being characterized using remotely sensed data as part of a larger ongoing USGS - BLM selenium-sodium-salinity-sediment study of the Gunnison Gorge National Conservation Area (GGNCA). This soil study focuses on the mapping of clay, sulfate, iron-oxide, and common rock-forming minerals and compounds and locating variations in distribution of these materials within the GGNCA. This status report examines the qualitative identification of surface materials using imaging spectroscopy data.

Six parallel and overlapping north-south trending flightlines of NASA/JPL MASTER (MODIS-ASTER Airborne Simulator) data cover the western part of the GGNCA between Montrose and Delta, Colorado at an approximate ground resolution of 5 meters. The Mancos Shale within this area occupies the floor of the Uncompahgre River valley between the Uncompahgre and Gunnison Gorge uplifts. Faulting, uplift, stream erosion, and other geomorphic processes have controlled soil formation on the Mancos Shale surface.

Absorption features of reflected light and emission properties of thermal infrared radiation were used to identify surface materials by associating spectral features of laboratory mineral spectra with features found in the airborne MASTER data. A variety of clay, sulfate, and iron-oxide minerals and compounds were identified using the 40 channels of MASTER reflectance data and common rock-forming minerals were grouped using the 10 channels of MASTER thermal infrared data. Selected areas within the GGNCA MASTER dataset were mapped. Mapped units used to characterize Mancos Shale soils were created by combining the identified and grouped minerals.