New Mexico Geological Society Annual Spring Meeting — Abstracts

The Raton-Clayton Volcanic Field (RCVF) is located along the eastern edge of the Great Plains province in northwestern New Mexico along the Jemez Lineament. Raton-Clayton volcanics are the eastern-most extent of Cenozoic volcanism until the Mid-Atlantic Ridge. The mechanism that causes melt generation beneath the Great Plains province is unclear. The RCVF offers the best chance to understand the mechanism driving melt generation in the Great Plains. The youngest phase of volcanism in the RCVF is the Capulin phase which ranges from ~1.5 Ma to 0.03 Ma. Only the youngest (~50 ka - ~30 ka) Capulin-phase volcanics were analyzed for this study. Whole-rock and single-crystal geochemical data is used to infer mantle composition and what processes have caused melting beneath the Great Plains province. Capulin-phase volcanics analyzed in this study are typically basalts, with some basaltic andesite and basaltic trachy andesite. Preliminary strontium isotope data suggest mixing between two slightly radiogenic sources (0.7042 and 0.7039) or indicates two separate sources of magma formation. Ratio/ratio plots of incompatible trace elements suggest two sources have contributed to Capulin basalts. Trace element data suggests contribution from both an Ocean Island Basalt (OIB)-like source and an enriched lithosphere source. Capulin-phase basalts show negative niobium anomalies. A mixture of approximately 60% OIB and 40% subduction enriched lithosphere can approximately explain trace element trends in Capulin-phase rocks. Deviations from the mixing trend may be explained by crustal contamination.