Structural Analysis of the La Veta Pass Area, Huerfano County, Colorado

Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Multi-Resolution Land Characteristics (MRLC) imagery were utilized in combination with kite aerial photography (KAP) and field measurements to analyze structural and geomorphic features associated with the thrust-fault complex near La Veta Pass, Colorado. The main objective of the research was to use field observations and remotely sensed data to determine the cause of the absence of the Dakota hogback near La Veta Pass. The structural features associated with the frontal thrust fault were identified through experimentation of various combinations of spectral bands and filters to produce natural and false-color composite Landsat images. Various combinations of linear and non-linear filters were used to detect sharp changes in contrast within the satellite imagery that may expose different aspects of the landscape. The spatial filters used during image processing included: Sobel edge detectors, high-pass filters, and Laplacian edge enhancements. These filters were utilized to exaggerate the structural features throughout the landscape.;The investigation of the general absence of the Dakota hogback revealed a complex relationship between the hogback and an interpreted imbricated thrust-fault zone located east of the frontal thrust fault. Numerous lineaments are observed north of La Veta Pass with a NW-SE trend, however, most of these features are concealed by Quaternary talus and landslide deposits between Mt. Maestas and Silver Mountain. It is possible that the interpreted imbricated zone containing multiple thrust faults could be partially responsible for the absence of the Dakota hogback. A striking similarity exists also between the complex at La Veta Pass and the complex near Cuchara which involves the White Peaks-Spanish Peaks intrusions and Mt. Maestas-Silver Mountain intrusions. The similarities between intrusions include: proximity, composition, radial dike complex, general structure, and location along the frontal thrust fault. The false-color composites proved to be the most effective method for distinguishing possible faults and their relationship to igneous complexes.