Martha Gabriela Gómez-Vasconcelos*
CONACYT–Instituto de Investigaciones en Ciencias de la Tierra, Universidad Michoacana de San Nicolás de
Hidalgo, Morelia, Michoacán, México, gabriela.gomez@umich.mx
Denis-Ramón Avellán
CONACYT–Instituto de Geofísica, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, denisavellan@gmail.com
José Luis Macías
Instituto de Geofísica, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, jlmv63@gmail.com
Guillermo Cisneros-Máximo
Instituto de Geofísica, Universidad Nacional Autónoma de México, Morelia, Michoacán, México, gcisneros@igeofisica.unam.mx
Juan Manuel Sánchez-Núñez
Instituto Politécnico Nacional–CIIEMAD, Gustavo A. Madero, Ciudad de México, México, jsancheznu@ipn.mx
Daniel P. Miggins
40Ar/39Ar Geochronology Laboratory, College of Earth, Ocean, and Atmospheric
Sciences, Oregon State University, Corvallis, Oregon 97331, USA, daniel.miggins@oregonstate.edu
Abstract
Understanding the feeder systems in scoria cones is essential because they serve as the conduits that feed
the most common eruptions worldwide. Feeder dikes and their emplacement are presumably controlled by the
tectonic stress field. However, the mechanism of dike propagation and structural control in monogenetic
scoria cones remains poorly understood, as well as the conditions that allow dike swarms in scoria cones and
in low magma-flux monogenetic volcanic fields.
This is the first direct study of a magma feeder system in the Michoacán-Guanajuato Volcanic Field in
central México. Quarrying in the Cerrito Colorado scoria cone displays six orthogonal feeder dikes—four of
them are N-S oriented, parallel to the least compressive stress, intruding preexisting faults, and two are
E-W oriented, perpendicular to the least compressive stress, forming their own fracture at the time of the
eruption.
Single feeder dikes are common in monogenetic volcanoes, but dike networks (swarms) can develop locally in
the vicinity of scoria cones and other vent structures. We suggest that bifurcation of feeder dikes can
result from temporary blockages of the conduit and during changes in the magma ascent rate and magma
pressure. Feeder dikes at the surface can appear as tabular dikes, cylindrical conduits, or as a combination
of both geometries. We suggest that tabular dikes splay-off tangentially, and cylindrical conduits bifurcate
radially and axially to the main vent. Our study attests to the complexity and structural control that even
small scoria cones can present.
*Corresponding author
Manuscript received 17 Mar. 2022. Revised manuscript received 30 June 2022.
Manuscript accepted 18 July 2022. Posted 10 Aug. 2022.
© The Geological Society of America, 2022. CC-BY-NC.
https://doi.org/10.1130/GSATG539A.1