MAPPING SURFACE PROCESSES TO DETERMINE THE INFLUENCE OF ACTIVE RIFTING ON RIVER AND BASIN EVOLUTION IN THE NORTHERN RIO GRANDE RIFT

Active tectonics play a significant role in the evolution of landscapes and the river systems within them. The Rio Grande Rift (RGR) provides a unique setting displaying the development of drainage systems in fault-bound basins. Tectonic activity, in the RGR, is well studied however, the interactions between active faults and drainage pathways remain insufficiently understood. Within the northern RGR, the Arkansas River, and its geomorphological features exemplify the impacts that active rifting can have on river evolution. Namely, the uplifted Poncha Block, CO, separates the upper Arkansas River Valley and the San Luis Basin, diverting the modern Arkansas River. New field data from imbricated clasts in fluvial gravels found on the block show flow trending northeast. North of the block, imbrication data indicates southward flow towards the modern Arkansas River. Additionally, surface and streamflow analysis in ArcPro, reveal knick points in the stream profiles of the Arkansas River and its tributaries. Coupled with work on clast provenance, stratigraphy, and thermochronology these results suggest that faulting in the RGR contributes to the river’s geomorphology and disequilibrium state. This highlights the influence of faulting in the RGR on the formation of the current Arkansas River and the structural evolution of its surrounding basins.