61-1 Preliminary Hypothesis of Geophysical, Geochemical and Structural Correlation of Hydrothermal Activity in Humming Bird Mine, Unaweep Canyon to the La Sal – Uncompahgre Region in Western Colorado

Abstract:

Unaweep Canyon is geomorphologically unique, featuring two mouths with East and West Creek flowing in opposite directions from a central drainage divide. Previous aerial magnetic surveys suggested high-magnetic anomalies near Nancy Hanks Gulch, potentially indicating a mafic source associated with rare earth elements. This study integrates ground-based magnetic surveying, structural mapping, and geochemical analysis to characterize these anomalies, estimate source depths, and test whether structural and weathering controls, rather than magnetic intensity alone, better explain mineral distribution across the survey area.

Magnetic data was collected with a GPS-integrated magnetometer and interpolated using an improved method, refining depth-to-source estimates beyond the standard Peter Half-Slope approach. This refined interpolation allows for more precise resolution of anomaly boundaries and source geometry than earlier aerial surveys provided. Structural data, supplemented by drone LiDAR, characterized fracture and fault geometry across the survey area. Multispectral drone analysis was done on areas with known silicification and mineralization, which was shown to correlate with regional structure. Geochemical and mineralogical analysis of hydrothermal vein material bearing quartz, green fluorite, and barite hosting copper mineralization was used to test a hypothesis for the magnetic source's composition. Hydrothermal activity seen in the area, supplemented by regional tectonic history, suggests an argument for mantle plumes in the region correlated between the La Sal – Uncompahgre.  Enriched supergene layering, reflecting leaching and oxidation, was also identified and evaluated as a control on near-surface mineral concentration, distinct from any signature tied to the underlying magnetic source.

Results show magnetic anomalies are less pronounced than aerial data suggested, and mineralization is concentrated in low-magnetic zones rather than high-magnetic ones. Structural trends correlate with vein orientation, supporting structural control on fluid pathways as a stronger predictor of mineralization than magnetic intensity. Regional comparison with analogous mineralized systems in the La Sal Mountains suggests these patterns reflect broader Colorado Plateau tectonic and hydrothermal processes rather than a phenomenon unique to Unaweep Canyon. Together, these results indicate that structural architecture and near-surface weathering processes play a larger role than magnetic source strength in governing where mineralization occurs, refining the current understanding of the relationship between geophysical signature, structural setting, and epithermal mineralization in Unaweep Canyon.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.