Genesis and evolution of the Cerro Prieto Volcanic Complex, Baja California, Mexico
Por:
Garcia-Sanchez, L., Macias, J. L., Sosa-Ceballos, G., Arce, J. L., Garduno-Monroy, V. H., Saucedo, R., Avellan, D. R., Rangel, E., Layer, P. W., Lopez-Loera, H., Rocha, V. S., Cisneros, G., Reyes-Agustin, G., Jimenez, A., Benowitz, J. A.
Publicada:
1 jun 2017
Categoría:
Geochemistry and petrology
Resumen:
The Cerro Prieto Volcanic Complex (CPVC), located in northwestern
Mexico, is the only surface manifestation of the Cerro Prieto Geothermal
Field, the third largest producer of geothermal energy in the world.
This geothermal field and the Salton Sea in the USA sit in a pull-apart
basin that belongs to the trans-tensional tectonic zone that includes
the San Andreas Fault system and the Salton Trough basin to the NWand
the East Pacific Rise to the SE. In spite of its strategic importance in
the generation of geothermal energy, the origin of Cerro Prieto and its
relationship with the geothermal reservoir were unknown. In this
contribution, we discuss the origin, evolution, and mechanisms of
formation of this small monogenetic volcano and the magmas that fed the
system. The volcanic complex is located on top of the Cerro Prieto left
lateral fault to the northwest of the Cerro Prieto Geothermal Field. The
complex consists of a lava cone and a series of domes (similar to 0.15
km(3)) protruding from Tertiary sandstones and recent unconsolidated
sediments of the alluvial plain of the Colorado River. The Cerro Prieto
Volcanic Complex consists of seven stratigraphic units emplaced in a
brief time span around 78-81 ka. Its activity began with the extrusion
of a dacitic lava that came into contact with water-saturated sediments,
causing brecciation of the lava. The activity continued with the
emplacement of dacitic domes and a dyke that were destroyed by a
phreatic explosion emplacing a lithic-rich breccia. This phreatic
explosion formed a 300-m-wide and 40-mdeep circular crater. The activity
then migrated similar to 650 m to the SW where three dacitic lava domes
were extruded and ended with the emplacement of a fissure-fed lava flow.
Subsequent remobilization of the rocks in the complex has generated
debris and hyperconcentrated flow deposits interbedded with fluviatile
sediments in the surrounding terrain. All rocks of the CPVC are dacites
with phenocrysts of plagioclase, orthopyroxene, and Fe-Ti oxides and
minor quartz. Gabbrodioritic dykes intruded in Tertiary sandstones and
siltstones of the local basement contain phenocrysts of plagioclase,
clinopyroxene, Fe-Ti oxides, and olivine. All CPVC rocks are chemically
homogeneous suggesting discrete modifications by crustal assimilation,
fractional crystallization, or magma mixing processes during upper
crustal residence. Aeromagnetic results suggest that the depth of the
magmatic source in the area is located below 3.5 km. CPVC rocks contain
chemical anomalies typical of subduction zones, which suggests that all
CPVC magmas could have been generated by partial melting of the remains
of the subducted Farallon plate.
Filiaciones:
Univ Nacl Autonoma Mexico, Inst Geofis, Posgrad Ciencias Tierra, Ciudad Mexico Coyoacan 04510, Mexico
Univ Nacl Autonoma Mexico, Inst Geofis, Antigua Carretera Patzcuaro 8701, Morelia 58190, Mich, Mexico
Univ Nacl Autonoma Mexico, Inst Geol, Mexico City 04510, DF, Mexico
Univ Michoacana, Inst Invest Ciencias Tierra, Morelia 58066, Mich, Mexico
Univ Autonoma San Luis Potosi, Inst Geol, Dr M Nava 5,Zona Univ, San Luis Potosi 78240, Slp, Mexico
Univ Nacl Autonoma Mexico, Catedra CONACYT, Inst Geofis, Antigua Carretera Patzcuaro 8701, Morelia 58190, Mich, Mexico
Univ Alaska, Coll Nat Sci & Math, Fairbanks, AK 99775 USA
Inst Potosino Invest Cient & Tecnol AC, Div Geociencias Aplicadas, Camino Presa San Jose 2055,Lomas 4a Secc, San Luis Potosi 78216, Slp, Mexico
GEA Alianza Explorac Geoterm, Pera 191,Col La Huerta, Morelia 58080, Mich, Mexico
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