DIAGENETIC MINERAL MAPPING IN THE CRETACEOUS BASELINE SANDSTONE, SOUTHERN NEVADA FROM COMBINATION OF LANDSAT, UAV, AND REFLECTANCE SPECTRAL DATA

Aerial/satellite imagery provides new insights into km-scale spatial distribution of diagenetic minerals to augment traditional field methods of ground-truth mineralogy/spectral data at outcrop scales. Here we use Landsat 8 OLI imagery processed in ENVI (30 m/pixel), DJI Phantom UAV/drone imagery to create orthomosaics (~10-20 cm/pixel), and ASD visible-near infrared reflectance data (cm-scale) to examine diagenetic mineral patterns across multiple scales within the Cretaceous Baseline Sandstone of southern Nevada. This integrated, nested-scales approach was applied to three focus areas within the formation: 1) coloration patterns along a stratigraphic section; 2) a formation-wide boundary between lightly altered rocks and intensely altered rocks; and 3) intense alteration exposed along the Baseline normal fault. The Landsat imagery was paired with the reflectance spectra to produce training classes for image classification that resulted in iron oxide and carbonate mineral maps. These maps combined with dm-scale resolution DEMs/DTMs created from drone imagery grant 3D views of mineral patterns in relation to structures and stratigraphy. Each focus area exhibits distinct diagenetic patterns indicative of separate episodes and processes of fluid flow-driven alteration. An early episode contemporaneous with deposition produced the formation-wide coloration patterns and was likely influenced by stratigraphic architecture and related textural properties (e.g. porosity) related to grain size and lithofacies distribution to produce the altered-unaltered boundary. A secondary episode of fluid flow occurred during Basin and Range extension and produced the intense, localized fault alteration. Observed widespread iron oxide mineral cement coloration patterns are visible in the processed Landsat mineral maps which provide a regional context to focus on specific localities where mineralogy can be validated by reflectance spectral profiles. The combination of the three mineralogy and imagery techniques increases precision in diagenetic pattern mapping, and elucidates structural, stratigraphic, and diagenetic relationships across multiples scales to interpret complex diagenetic histories of clastic formations.