Major and trace element geochemistry and Sr–Nd isotopic constraints on mafic volcanic rocks from the Ventura-Espiritu Santo Volcanic Field, San Luis Potosi, Mexico: Petrogenesis and tectonic implications of Cenozoic volcanism in the Basin and Range Province

Abstract

The Ventura Espiritu Santo Volcanic Field (VESVF), located in the central part of the Mesa Central (MC), Mexico, is a monogenetic volcanic field dominated by Late Pleistocene mafic volcanism. It covers an area of approximately 100 km between the localities of Cúcamo and Santa Lucia and is emplaced on a basement composed of metamorphic rocks of the Sierra de Salinas and Triassic marine sequences that are tectonically overlain by the Guerrero Terrane. This study presents new petrographic observations, whole-rock major-and trace-element geochemistry, and Sr-Nd isotopic data for mafic rocks from the Cúcamo, El Rosario, and Santa Lucía areas to constrain the magmatic processes involved in the origin and evolution. Chondrite-normalized REE patterns display moderate enrichment in Light Rare Earth Elements (LREE) accompanied by slight depletion in Heavy Rare Earth Elements (HREE) and absence of an Eu anomaly. Primitive mantle-normalized diagrams show prominent positive anomalies in K, P, and Ti, together with negative anomalies in Pb. The absence of Nb-Ta troughs, together with multidimensional discrimination diagrams, could indicate an affinity to intraplate geochemical signature. Isotopic composition (87Sr/86Sri = [0.70307–0.70353, εNd = +5.8 to +6.3] suggests derivation from an enriched mantle source. The trace-element behavior, supported by geochemical modeling, further indicates that the mafic rocks were generated by low degree of partial melting of the enriched lherzolite upper lithospheric mantle source, pointing to a tectonic environment dominated by lithospheric extension and asthenospheric upwelling.