The southern Guadalajara volcanic chain, Jalisco, México

Abstract

The southem Guadalajara Volcanic Chain consists of eight small lava and cinder eones of Plio-Pleistocene age which follow a NW-SE trend through the southem portion of the city of Guadalajara. This chain and numerous other volcanic alignments in the western Mexican Volcanic Belt are related to a major on-going episode of cristal rifting; and provide valuable information concerning the upper crustal stress field at the time of eruption. Lava samples from the southem Guadalajara eones are olivine-bearing basaltic andesites of calc-alkaline carácter showing little compositional variation. Similar basaltic andesites occur at Cqlima, Paricutín, Jorullo, and other volcanoes in the western Mexican Volcanic Beli, particularly those closer to the Middle America Trench. Basaltic andesite is probably thé most abundant magma type rising from upper-mantle and lower-crustal depths in the region.