Ayulta

The Ayulta Volcanic Field of Jalisco, Mexico is located in the volcanic front of the western Mexican Volcanic Belt. Volcanic rocks occur to the north and east of the village of Ayulta, with basement rocks including the Cretaceous, andesitic Jalisco breccia resting on detrital red sandstones and conglomerates. The field hosts both calc-alkaline (andesitic) and alkaline lavas, with the latter including an alkali basaltic-hawaiitic series and a potassic series of olivine and augite minettes and trachy-lavas. Phenocrysts within the minette include augite, phlogopite, and apatite, with cumulate-textured phlogopite clinopyroxenite and hornblende-gabbro xenoliths found entrained within the augite minette flow. The broad spectrum of alkaline and hydrous lavas is hypothesised to result from melting of an enriched subcontinental lithospheric mantle source during Tertiary Sierra Madre Occidental magmatism. Geochemical data including whole rock major and trace element, and mineral chemical data can be found in Righter and Rosas-Elguera (2000).