Geology, geochronology and tectonic setting of late Cenozoic volcanism along the southwestern Gulf of Mexico: The Eastern Alkaline Province revisited

Coupled with previous studies, our data demonstrate the occurrence of three magmatic episodes in Veracruz: 1) A Middle Miocene (∼15-11 Ma) episode in southern Veracruz (Palma Sola, Anegada, and Los Tuxtlas); 2) A Late Miocene to Early Pliocene (∼7.5-3 Ma) pulse of mafic alkaline volcanism throughout the study region; and 3) A Late Pliocene to Quaternary transitional to calc-alkaline volcanism in southern Veracruz (Palma Sola, Los Tuxtlas). Whereas the first and third episodes may be considered part of the subduction-related Trans-Mexican Volcanic Belt, the second pulse of mafic alkaline volcanism has a more complex origin. The absence of significant extensional faulting precludes a rift origin. We favor a model in which a transient thermal anomaly and melting of the mantle was triggered by the tearing and detachment of part of the subducted slab.