Journal ArticleDOI
Plagioclase-free andesites from Zitácuaro (Michoacán), Mexico: petrology and experimental constraints
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TLDR
In this article, a small cluster of Pleistocene andesite cones and flows are classified into two distinct groups: high-magnesium andesites (>6% MgO, 57-59% SiO2), conveniently called basalt-andesites, with phenocrysts of orthopyroxene and augite, or augite and olivine, at pressures of about 1 kbar.Abstract:
Approximately 150 km west of Mexico City in the central part of the Mexican Volcanic Belt (MVB) near Zitacuaro, Mexico, young volcanism has produced shield volcanoes, large volume silicic deposits, and fault-related basalt and andesite lava flows and cinder cones. This paper concerns a small cluster of Pleistocene andesite cones and flows which can be separated into two distinct groups: high-magnesium andesites (>6% MgO, 57–59% SiO2), conveniently called basaltic andesites, with phenocrysts of orthopyroxene and augite, or augite and olivine; and andesites (60–62% SiO2, 3 wt%) at pressures of about 1 kbar. Compared to basaltic andesites of western Mexico, the Zitacuaro basaltic andesites have ∼2 wt% lower Al2O3 concentrations, which causes plagioclase to precipitate at significantly lower temperatures, and it therefore follows the crystallization sequence: olivine, augite, and orthopyroxene. Based on ubiquitous quartz xenocrysts, with glassy rhyolitic inclusions, a reasonable conclusion is that substantial mixing of a quartz-bearing rhyolitic magma with a parental basaltic andesite has occurred at low pressure (shallow depth), and this would account for the low Al2O3 concentrations in the Zitacuaro basaltic andesites. Whatever the mechanism of incorporation, the quartz xenocrysts are evidence of contamination of basaltic magma with more siliceous material, thus making it difficult to use these magmas as indicators of mantle melting processes.read more
Citations
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Journal ArticleDOI
The Genesis of Intermediate and Silicic Magmas in Deep Crustal Hot Zones
TL;DR: In this article, a model for the generation of intermediate and silicic igneous rocks is presented, based on experimental data and numerical modeling, which is directed at subduction-related magmatism, but has general applicability to magmas generated in other plate tectonic settings, including continental rift zones.
Journal ArticleDOI
Stability and chemical equilibrium of amphibole in calc-alkaline magmas: an overview, new thermobarometric formulations and application to subduction-related volcanoes
TL;DR: In this article, a rigorous analysis of the physical-chemical, compositional and textural relationships of amphibole stability and the development of new thermobarometric formulations for amphibole-bearing calc-alkaline products of subduction-related systems is presented.
Journal ArticleDOI
Fractional crystallization and mantle-melting controls on calc-alkaline differentiation trends
Timothy L. Grove,Linda T. Elkins-Tanton,Stephen W. Parman,Nilanjan Chatterjee,Othmar Müntener,Glenn A. Gaetani +5 more
TL;DR: The phase relations of primitive andesites and basaltic andesite from the Mt Shasta region, N California have been determined over a range of pressure and temperature conditions and H2O contents as mentioned in this paper.
Journal ArticleDOI
The dynamic history of the Trans-Mexican Volcanic Belt and the Mexico subduction zone
TL;DR: The Trans-Mexican Volcanic Belt (TMVB) is a 1000 km long Neogene continental arc showing a large variation in composition and volcanic style, and an intra-arc extensional tectonics.
Journal ArticleDOI
Petrologic Reconstruction of Magmatic System Variables and Processes
Jon D Blundy,Kathy Cashman +1 more
TL;DR: In this article, the authors present some of the current petrological techniques that can be used for studying eruptive products and for constraining key magmatic variables such as pressure, temperature, and volatile content.
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.
Book ChapterDOI
ORIGIN OF GRANITE IN THE LIGHT OF EXPERIMENTAL STUDIES IN THE SYSTEM NaAlSi3O8–KAlSi3O8–SiO2–H2O
O. F. Tuttle,N. L. Bowen +1 more
Journal ArticleDOI
Gradients in silicic magma chambers: Implications for lithospheric magmatism
TL;DR: In this article, the authors studied the effect of pre-emptive and preemptive gradients in T and O 2 in a variety of compositionally zoned ash flow tuffs.
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.
Journal ArticleDOI
The compressibility of silicate liquids containing Fe 2 O 3 and the effect of composition, temperature, oxygen fugacity and pressure on their redox states
TL;DR: In this paper, the authors extended the empirical expression of Sack et al. to allow the calculation of Fe-redox equilibrium in a natural silicate liquid as a function of composition, temperature, fo2 and pressure; a more formal thermodynamic expression is presented in the Appendix.