The Zitacuaro volcanic complex, Michoacan, Mexico; magmatic and eruptive history of a resurgent caldera.

Abstract

The Zitacuaro Volcanic Complex ZVC rises on a basement of metamorphic rocks of Late Jurassic-Early Cretaceous age, and volcanic rocks, limestones, and red beds of Cretaceous age. Volcanic activity related to the Trans-Mexican Volcanic Belt started during Early Miocene with the eruption of calc-alkaline andesites that formed a primitive stratovolcano covering an area about 30 kmX15 km. A major change in eruptive style occurred during Middle Miocene, when a caldera structure formed, Las Tres Chicas Caldera, approximately 30 km in diameter and dated about 12 Ma. Post-caldera activity consisted of three eruptive episodes of intra-caldera dome resurgence around 12 Ma, 5 Ma, and 0.5 Ma. Each episode featured the intrusion of dacitic central domes, the generation of pyroclastic flows and peri-caldera andesitic lava flows. The activity at the ZVC features recurrent volcanic episodes, the most recent one with emplacement of young resurgent domes such as Cacique. Local seismic activity in the area felt at Zitacuaro, is persistent. The ZVC should be considered as a potentially active volcanic zone.

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