Hydrogeology of the La Jencia and Socorro basins: data synthesis and perspectives for further research
— Marissa M. Fichera, Alex J. Rinehart, and Ethan Williams

The Socorro and La Jencia Basins are two adjacent, hydrologically connected groundwater basins located along the Rio Grande rift in central New Mexico. The groundwater flow system within and between these two basins is complex, and current understanding is limited by the absence of a high-resolution geologic framework. Geochemical studies provide a conceptual understanding of groundwater flow by identifying groundwater and spring waters of epigenic/meteoric, geothermal (circulation and heating of recharged waters), and endogenic (mantle- and crustal-derived) origins. This paper aims to expand on these groundwater flow and recharge source hypotheses. We integrate new stable isotope data collected from sites located along Socorro Canyon and the Rio Grande with legacy water quality, tracer, and water level data. Socorro Canyon is one of three east-west-trending canyons within the extensively faulted Socorro-Lemitar Mountains—a north-south-trending mountain range that bisects the La Jencia and Socorro Basins. Water quality in these canyons is controlled by water-rock interactions and contains a mix of young and old waters, indicating a series of nested, deep groundwater flow paths within the La Jencia Basin. The Socorro-Lemitar Mountains act generally as a barrier to flow between the basins, with a series of springs rising in through-cutting canyons. Nonetheless, the fractured nature of the Socorro-Lemitar Mountains suggests that interflow may occur over long periods of time. The majority of waters in the Socorro Basin are similar to Rio Grande waters, suggesting generally recent recharge of the shallow aquifer system. However, regional geochemistry of the Rio Grande and Low-Flow Conveyance Channel (LFCC) waters show that there are regions of upwelling, chloride-rich brines. Two sources are possible for these: (1) deep, axial basin gravity-driven circulation; and (2) lateral upwelling of waters recharged in the Magdalena Mountains. We believe that axial flow is more likely. Preliminary interpretations are consistent with findings from similarly structured surrounding rift basins; however, additional subsurface data is needed (geologic and hydrologic) for further understanding beyond the shallow flow system.