Geology and radiometric dating of Quaternary monogenetic volcanism in the western Zacapu lacustrine basin (Michoacan, Mexico): implications for archeology and future hazard evaluations
Por:
Reyes-Guzmán N., Siebe C., Chevrel M.O., Guilbaud M.-N., Salinas S., Layer P.
Publicada:
1 feb 2018
Categoría:
Geochemistry and petrology
Resumen:
The Zacapu lacustrine basin is located in the north-central part of the
Michoacan-Guanajuato volcanic field (MGVF), which constitutes the
west-central segment of the Trans-Mexican Volcanic Belt. Geological
mapping of a 395 km(2) quadrangle encompassing the western margin of the
basin, Ar-40/Ar-39 and C-14 radiometric dating, whole-rock chemical and
petrographic analyses of volcanic products provide information on the
stratigraphy, erupted volumes, age, and composition of the volcanoes.
Although volcanism in the MGVF initiated since at least 5 Ma ago, rocks
in the western Zacapu lacustrine basin are all younger than similar to
2.1 Ma. A total of 47 volcanoes were identified and include 19 viscous
lava flows (similar to 40 vol.%), 17 scoria cones with associated lava
flows (similar to 36 vol.%), seven lava shields (similar to 15 vol.%),
three domes (similar to 6 vol.%), and one maar (similar to 2 vol.%).
Erupted products are dominantly andesites with 42 km(3) (similar to 86
vol.%) followed by 4 km(3) of dacite (similar to 8 vol.%), 1.4 km(3)
of basaltic trachyandesite (similar to 3 vol.%), 1 km3 of basaltic
andesite (similar to 2 vol.%), and 0.14 km(3) of rhyolite (similar to
0.3 vol.%). Eruptive centers are commonly aligned ENE-WSW following the
direction of the regional Cuitzeo Fault System. Over time, the high
frequency of eruptions and consequent accumulation of lavas and
pyroclastic materials pushed the lake's shore stepwise toward the
southeast. Eruptions appear to have clustered through time. One cluster
occurred during the Late Pleistocene between similar to 27,000 and
similar to 21,300 BC when four volcanoes erupted. A second cluster
formed during the Late Holocene, between similar to 1500 BC and similar
to AD 900, when four closely spaced monogenetic vents erupted forming
thick viscous `a'a to blocky flows on the margin of the lacustrine
flats. For still poorly understood reasons, these apparently
inhospitable lava flows were attractive to human settlement and
eventually became one of the most densely populated heartlands of the
pre-Hispanic Tarascan civilization. With an average eruption recurrence
interval of similar to 900 years during the Late Holocene the western
Zacapu lacustrine basin is one of the most active areas in the MGVF and
should hence be of focal interest for regional volcanic risk
evaluations.
Filiaciones:
Reyes-Guzmán N.:
Departamento de Vulcanología, Instituto de Geofísica, Universidad Nacional Autónoma de México, Coyoacán, Mexico
Siebe C.:
Departamento de Vulcanología, Instituto de Geofísica, Universidad Nacional Autónoma de México, Coyoacán, Mexico
Chevrel M.O.:
Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, France
Guilbaud M.-N.:
Departamento de Vulcanología, Instituto de Geofísica, Universidad Nacional Autónoma de México, Coyoacán, Mexico
Salinas S.:
División de Ingeniería en Ciencias de la Tierra, Facultad de Ingeniería, Universidad Nacional Autónoma de México, Coyoacán, Mexico
Layer P.:
Department of Geology and Geophysics, University of Alaska Fairbanks, Fairbanks, AK, United States
|