STRATIGRAPHIC INSIGHTS INTO TECTONIC AND SEDIMENTARY EVOLUTION OF THE RIO GRANDE RIFT

The Rio Grande Rift represents a tectonically active extensional region that records the interplay between tectonic extension, sedimentation, and volcanism in a continental rift basin. This research investigates the stratigraphy of the Dry Union and Santa Fe Formations and their depositional and tectonic history. Stratigraphic logging, clast counts, and sample analyses were conducted across several exposures to identify depositional environments, paleocurrents, and sediment provenances.

The stratigraphic columns reveal distinct depositional environments and tectonic controls. Coarse-grained conglomerates with imbrications suggest high-energy fluvial systems linked to active faulting and steep sedimentary gradients, reflecting episodic uplift and rapid sediment transport. Interbedded fine sands locally with carbonate nodules represent low-energy floodplain or lacustrine settings, punctuated by periods of pedogenesis under semi-arid conditions. Cross-bedded sandstones with granule lenses indicate transitional fluvial channels, while interbedded tuffaceous layers document episodic volcanic activity, providing important chronostratigraphic markers.

Further analysis of the stratigraphic columns reveals shifts in depositional energy, with coarse-grained intervals tied to tectonic activity or channel migrations, while finer-grained intervals suggest periods of low-energy and more stable conditions. The observations of cross-bedded sandstones, volcanic tufts, and paleosols points to changes in sediment transport, volcanic activity, and possibly base-level. These interpretations refine our understanding of the Rio Grande Rift’s sedimentary framework, aiding in reconstructions of the timing of fault activity and sediment dispersal. The stratigraphic framework provides important insights into resource potential and the tectonic evolution of the rift system.