Quaternary minettes and associated volcanic rocks of Mascota, western Mexico: a consequence of plate extension above a subduction modified mantle wedge

Article Abstract:

The Quaternary volcanic rocks of Mascota, western Mexico, comprise minettes, basaltic andesites, and absarokites occurring within two grabens of the Jalisco block. A high range of relative oxygen fugacities and a high Mg number characterize the Mascota suite of rocks. These features indicate that the magma was generated by partial melting of a lherzolite source. The lavas erupted via ascent paths created due to plate extension. Experiments help to estimate the pressures, temperatures, and water concentrations that controlled the growth of the observed phenocrysts assemblages in the rocks.

Author: Lange, Rebecca A., Carmichael, Ian S.E., Luhr, James F.
Mexico, Observations, Neotectonics, Petrogenesis, Alkalic igneous rocks

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Plagioclase-free andesites from Zitacuaro (Michoacan), Mexico: petrology and experimental constraints

Article Abstract:

A study was conducted to investigate young volcanism near Zitacuaro in eastern Michoacan, Mexico and the occurrence of plagioclase-free andesites and basaltic andesites with quartz xenocrysts in the Valley of Mexico. The approximation of the phenocryst equilibration conditions for the plagioclase-free andesite magma was performed through phase equilibria experiments. Results revealed that Zitacuaro andesites were originally equilibrated at 970 degrees C and pressure greater than 1.5 kilobars. There were partial resorption and phenocrysts during ascent and eruption.

Author: Carmichael, Ian S.E., Blatter, Dawnika L.
Natural resources, Rocks, Igneous, Igneous rocks, Michoacan, Mexico

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Alkaline and calc-alkaline lavas near Los Volcanes, Jalisco, Mexico: geochemical diversity and its significance in volcanic arcs

Article Abstract:

Mineralogical analyses of calc-alkaline and alkaline samples at the Plio-Quaternary eruptions near Los Volcanes, Jalisco, Mexico, revealed that complex magma sources were involved in lava formation. This diverse magma composition, which is characteristic of the whole volcanic arc, was attributed to the interaction between volcanic and tectonic activities resulting in different regional mineralogical abundances. Furthermore, the enrichment of varying amounts of major and trace elements manifested the heterogeneity found in subterranean magma sources.

Author: Wallace, Paul, Carmichael, Ian S.E.
Lava, Apatite, Apatites, Island arcs, Amphiboles, Jalisco, Mexico

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Subjects list: Research, Natural history, Volcanism
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