Investigating the Magmatic Plumbing System of a Monogenetic Scoria Cone: A Field and Laboratory Study of the Cienega Scoria Cone, Cerros del Rio Volcanic Field, New Mexico

©2018. American Geophysical Union. All Rights Reserved. Data on the evolution of magmatic plumbing systems are essential for the understanding of magma motion in monogenetic volcanoes and associated volcanic hazard. Combined field (relationships and petrography) and laboratory (rock magnetism, anisotropy of magnetic susceptibility, and paleomagnetism) analysis of a quarried scoria cone offers a unique opportunity to study its magmatic plumbing system. In this study magma emplacement processes were constrained using these methods at two vents, Cerro Pequeño and Cerro Grande, of the composite Cienega scoria cone volcano, in New Mexico, USA. The dikes and lava flows associated with Cerro Pequeño were emplaced in two stages within a short period of time relative to secular variation. In the first stage, the magma was injected into the main conduit of the Cerro Pequeño and then channeled into secondary conduits (e.g., the exposed dike system) moving away from the vent. In the late stage, magma from the northern Cerro Grande was injected into the Cerro Pequeño dike system toward its main vent. The dynamic evolution of the magmatic system observed at the Cienega volcano is similar to that observed in other larger volcanic edifices. As in this study, the investigation of the magma plumbing systems of many scoria cones reveals that the subsurface magmatic system involves multiple feeder conduits that evolve during the life of the volcanic system. This study provides significant insight for the characterization of magma propagation at the shallow level beneath the volcanic edifice and highlights the related hazards associated with small active volcanic systems worldwide