DIGITAL GEOLOGIC MAP AND DATABASE OF THE COLLIER DRAW-BENAVIDEZ RANCH QUADS, NEW MEXICO

As an off-shoot of the Middle Rio Grande Basin project, a prototype digital geologic map and linked database of the Collier Draw-Benavidez Ranch area of New Mexico is being developed within the Arc/Info-ERDAS Imagine environment. The goal of this project has been to develop techniques to exploit geologic information in satellite images while directly creating surficial and bedrock geologic boundary vector data in GIS-based formats and to integrate these vector data with databases containing the physical characteristics (lithology, mineralogy, chemistry, grain-size, spectral properties, etc.) associated with the defined rock/soil units. Currently, a well-defined method for linking quantitative information of the physical and spectral characteristics of rock and soil samples with their corresponding geologic map units is lacking for USGS geologic maps.

Laboratory analysis and spectral calibration/integration with the sample data are ongoing. Reconnisance field work and sample collection have been completed within the map area. The surficial geology of the area has been mapped by Jim Yount at 1:100,000 scale and will be folded into the geologic database. A preliminary digital geologic contact map has been produced using various processed Landsat color composites combined with high-resolution aerial photographs as an image base and interactively drawing vector contacts directly on-screen using ERDAS Imagine and ArcInfo software. The geologic map units will be linked to other GIS databases containing the quantitative information that define the map unit's physical characteristics. This information is being generated from several sources including Landsat TM spectral data, existing laboratory spectral libraries of rocks and minerals, and the physical and chemical properties extracted from rock/soil samples collected from representative units in the map area.