Remote Sensing Studies

We have used Landsat and Radarsat images of the BP and Oasis structures in an effort to determine more about the local geology and the morphologic dimensions of the structures. The Landsat data have a resolution of 30 m and were acquired in multiple wavelengths. Radarsat data were acquired at much longer wavelengths attaining a variable resolution of 10 to 100 m, but have the ability to penetrate thin surficial sand and are sensitive to changes in roughness and dielectric constants.

For both the BP and Oasis structures a variety of images were produced in order to discriminate among the lithologies present at the site and to determine various morphometric dimensions. We used: a) false color Landsat images, combining bands 1, 4, 7 and bands 2, 3, 5; b) various stretches (linear, 2%, and Gaussian) of these false color composites that merely exaggerate the contrast of the scene, making features appear brighter or darker than they actually are; and c) spectral classifications of each of the scenes. As there is very little difference in the spectral properties of the materials and there are only a few spectral bands in the Landsat images, the number of spectral classes was limited to five. Several techniques were used, such as Isodata, K-mean, and principal components, to spectrally group the materials. These analyses show that most of the bedrock units have approximately the same spectral character, within the constraints of the limited spectral channels. Finally, (d) radar data were investigated.

Fig. 4. Landsat image of the BP structure. CU indicates the Central Uplift / Inner Ring; MR indicates Middle Ring; OR indicates the Outer Ring. A denotes the north-trending bedrock ridge discussed in the text that possibly limits the lateral extent of the structure.

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