Journal ArticleDOI
Petrology of Volcán Tequila, Jalisco, Mexico: disequilibrium phenocryst assemblages and evolution of the subvolcanic magma system
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In this paper, the authors show that hornblende-bearing andesite, dacite, and rhyodacite lava flows from the Tequila volcano are similar to those from the flanks of the volcano.Abstract:
Volcan Tequila is an extinct stratovolcano in the western Mexican Volcanic Belt that has erupted lavas ranging from andesite to rhyolite during the last 0.9 Ma. Following an early period of rhyolitic volcanism, the main edifice of the volcano was constructed by central vent eruptions that produced ∼ 25 km3 of pyroxene-andesite. At about 0.2 Ma central activity ceased and numerous flows of hornblende-bearing andesite, dacite, and rhyodacite erupted from vents located around the flanks of the volcano. Bimodal plagioclase phenocryst rim compositions in lavas from both the main edifice and the flanks indicate that magma mixing commonly occurred shortly prior to or during eruption. Compositions of endmember magmas involved in mixing, as constrained by whole-rock major and trace element abundances, phenocryst compositions, and mineral-melt exchange equilibria, are similar to those of some lavas erupted from the central vent and on the flanks of the volcano. Estimated pre-eruptive temperatures for hornblende-bearing lavas (970°–830°C) are systematically lower than for lavas that lack hornblende (1045°–970°C), whereas magmatic H2O contents are systematically higher for hornblende-bearing lavas. In addition to stabilizing hornblende, high magmatic water contents promoted crystallization of calcic plagioclase (An70–82). Frequent injections of magma into the base of the subvolcanic plumbing system followed by eruption of mixed magma probably prevented formation of large volumes of silicic magma, which have caused paroxysmal, caldera-forming eruptions at other stratovolcanoes in western Mexico. The later stages of volcanic activity, represented by the flank lavas, indicate a change from a large magma storage reservoir to numerous small ones that developed along a NW-trending zone parallel to regional fault trends. Sr and Nd isotopic data for lavas from the Tequila region and other volcanoes in western Mexico demonstrate that differentiated calc-alkaline magmas are formed primarily through crystal fractionation of mantle-derived calc-alkaline basalt coupled with assimilation of crustal material.read more
Citations
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Journal ArticleDOI
The andesite aqueduct: perspectives on the evolution of intermediate magmatism in west-central (105–99°W) Mexico
TL;DR: In this paper, the authors used phase equilibria on the plagioclase-rich andesites of Volcan Colima, Mexico, to determine the amount of water required to equilibrate with an olivine-orthopyroxene mantle source.
Journal ArticleDOI
Quaternary minettes and associated volcanic rocks of Mascota, western Mexico: a consequence of plate extension above a subduction modified mantle wedge
TL;DR: In this paper, the Mascota series shows a correlation between K2O and Mg#, with a variable contribution of phlogopite and apatite from veins throughout the lherzolitic assemblage.
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Petrogénesis ígnea de la Faja Volcánica Transmexicana
TL;DR: The Faja Volcanica Transmexicana (FVL) is the result of one of the sistemas tectonicos convergentes mas complejos del planeta, el objeto de mas de un siglo de investigaciones cienti fi fi cas, and tambien el centro de las controversias mas notables sobre la geologia mexicana as discussed by the authors.
Journal ArticleDOI
Tectonics and volcanism of Sierra Chichinautzin : extension at the front of the Central Trans-Mexican Volcanic belt
TL;DR: The Sierra Chichinautzin volcanic field (SCN) is a key area for the understanding of the Trans-Mexican Volcanic Belt (TMVB) as discussed by the authors.
References
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Book
Orogenic Andesites and Plate Tectonics
TL;DR: In this article, the authors define Orogenic Andesite and discuss its properties and properties, including the following: 1.1 Topography, gravity, heat flow, and conductivity.
Journal ArticleDOI
Geothermobarometry in Four-phase Lherzolites II. New Thermobarometers, and Practical Assessment of Existing Thermobarometers
Gerhard P. Brey,T. Köhler +1 more
Journal ArticleDOI
Pyroxene thermometry in simple and complex systems
TL;DR: In this article, a semi-empirical equation of state for the diopside enstatite miscibility gap has been proposed for ortho-and clinopyroxene solid solutions.
Journal ArticleDOI
Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism
TL;DR: The phase relations of natural aphyric high-alumina basalts and their intrusive equivalents were determined through rock-melting experiments at 2 kb, H2O-saturated with fO2 buffered at NNO.
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