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Monogenetic, polycyclic, and polygenetic small-scale volcanoes in Central Mexico: examples of transitional eruptive styles

Carrasco-Núñez, G.1, Ort, M. H.2, Cavazos-Alvarez, J A.2, Dávila-Harris, P.3

  • Affiliations:  1 Instituto de Geociencias, Universidad Nacional Autónoma de México, Querétaro, México; 2 Northern Arizona University, Flagstaff, AZ, USA;3 IPICYT, San Luis Potosí, México. 

  • Presentation type: Talk

  • Presentation time: Thursday 14:15 - 14:30, Room S160

  • Programme No: 3.7.1

  • Theme 3 > Session 7

Abstract

A simple classification of volcanoes into monogenetic and polygenetic volcanic structures typically relates the former to small-volume, short-lived single eruptions (from days to several years) forming small-scale volcanoes and the latter to large-volume, long-lived eruption periods and large-scale volcanoes. However, numerous studies of small-scale volcanoes show complex eruptive behaviors, in some cases of a polygenetic nature and even transitional polycyclic eruptions, including multiple and complex eruptive phases of small volumes of magma separated by long periods (hundreds to thousands of years). Irrespective of the definition of these names, it is important to identify the role of each factor controlling the eruptive style, such as variations in magma flux, composition, water availability, vent migration, explosion depths, country-rock structure, and tectonic setting, which affect how magmatic or phreatomagmatic an eruption is and the volcanic structure it builds (scoria-cinder cones, tuff-rings, maars sst, domes, and combinations/complexes). We describe transitions between magmatic and phreatomagmatic eruptive styles observed in several Mexican small volcanoes (e.g. Alchichica, Joyuela, Cíntora, La Alberca basaltic maars), eruptions dominated by phreatomagmatic culminating with magmatic activity (e.g. Tepexitl basaltic maar),  mixed and complex activity (e.g. Joya Honda, Aljojuca basaltic maars), magmatic activity producing polycyclic cones (e.g. El Volcancillo; Antofagasta cones), and rhyolitic volcanoes (e.g. Tepexitl tuff-ring), some showing polycyclic (e.g. Cerro Pinto tuff and dome complex) or polygenetic behavior (e.g. Cerro Pizarro dome). We discuss how the above factors affect the formation of small-scale volcanic landforms and their volcanic behavior.