Response of the fluvial erosive system in the Ameca and Santiago basins, central-western Mexico, to tectonic and volcanic controls

Abstract

The Late Miocene volcanism related to the Trans-Mexican Volcanic Belt modified the paths of sediment transport from the Late Oligocene-Early Miocene landscape on west-central Mexico. We hypothesize that the ignimbrites from the Sierra Madre Occidental have had reached the floodplain of the Puerto Vallarta Graben. The volcanic activity of the Trans-Mexican Volcanic Belt at the south of the Sierra Madre Occidental, probably changed the sediment discharge from the Sierra Madre Occidental towards the floodplain of Nayarit trough the Santiago River. Such event restrained the sediment transport from the Sierra Madre Occidental towards the Puerto Vallarta Graben and Bahía de Banderas isolating a part of the landscape of the Ameca river basin which, nowadays, feeds the sediments that forms the floodplain of the Puerto Vallarta Graben. The Late Oligocene to Early Miocene age distribution of detrital zircons close to the mouths of Santiago and Ameca rivers support the idea that both rivers share sediments originated from the Sierra Madre Occidental.