294-10 Digital Conversion and Geospatial Analysis of an Analog Geologic Map of a Late Paleogene Volcanic Field, Southeastern California

Session: Geologic Mapping (Posters)

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Abstract:

During the mid-Tertiary period, widespread volcanism in the southwestern United States occurred during the waning stages of subduction of the Farallon Plate beneath North America. Eroded remnants of volcanic fields across southeastern California and western Arizona were mapped using conventional methods and reported in theses and dissertations during the 1970s and 1980s. For this study, an analog geologic map of a late Paleogene volcanic field in the western Little Chuckwalla Mountains (LCM) was converted into a digital format suitable for geospatial analysis. The map covers 67 km² at a scale of 1:12,000 (Mayo, 1990, unpublished MS thesis). The LCM volcanic field comprises a 1,500 m thick southeast-dipping (N30°E/10–45°SE) homocline of volcanic and sedimentary rocks, cut by northwest-striking hypabyssal dikes and broken by northwest-dipping normal faults. The analog map was scanned using a large-format digital scanner (TIFF format) and georeferenced in ArcGIS Pro using a first-order polynomial (affine) transformation with 125 ground control points (RMS = 0.664 m). Data were projected to the WGS 1984 UTM Zone 11N coordinate system. Contact and fault traces were digitized from the image and used to generate polygons delineating lithological units. Orientation data from original field measurements were integrated as point features. The workflow followed the USGS Geologic Map Schema (GeMS). New cross-sections and stratigraphic columns were constructed to support geospatial analysis. Because no publicly available datasets match the detail in Mayo’s original work, this digitization preserves fine-scale structural and lithologic features. The dataset enables GIS-based querying, supports quantitative analysis, and facilitates integration with other geoscientific datasets. The workflow is reproducible and aids reconstruction of regional volcanic and tectonic history.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8580

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