ABSTRACT: Using Landsat TM Data to Detect Surficial Changes Associated with Hydrocarbon Seepage, Sheep Mountain Anticline, Wyoming

Veena Malhotra Tabbutt, Richard W. Birnie, John R. Everett

An interactive image processing demonstration has been developed to illustrate the usefulness and limitations of satellite TM (Thematic Mapper) data in the detection of subtle surficial changes associated with hydrocarbon seepage. Using an image analysis system, the user is guided through a series of enhancements and manipulations designed to illustrate specific band combinations and image analysis techniques that best isolate areas of surface alteration due to hydrocarbon seepage.

The region chosen for this study is Sheep Mountain Anticline, Bighorn basin, Wyoming. An intensive study has recently been completed in this area where several surface indications of hydrocarbon seepage were identified. Data examined in this study include Landsat TM data, field spectroradiometer data, and correlative field data including clay mineralogy, soil pH, and soil mineralogy. Bleaching of an iron-oxide-rich formation was indicated by a decrease in a TM band 3/1 ratio in conjunction with an increase in total reflected radiance. This corresponded spatially with an absence of kaolinite within shale-rich formations, a decrease in soil pH over the Cloverly Formation, the presence of uranium minerals, and a decrease in magnetic intensity of iron-bearing minerals. Techniques found mo t useful for isolating bleached areas included band ratios, band classifications, band addition, principal component analysis, and intensity-hue-saturation transformations.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990