The hydrous phase equilibria (to 3 kbar) of an andesite and basaltic andesite from western Mexico: constraints on water content and conditions of phenocryst growth

  title={The hydrous phase equilibria (to 3 kbar) of an andesite and basaltic andesite from western Mexico: constraints on water content and conditions of phenocryst growth},
  author={G. Moore and I. Carmichael},
  journal={Contributions to Mineralogy and Petrology},
Abstract We have conducted high pressure (to 3 kbar), water saturated melting experiments on an andesite (62 wt% SiO2) and a basaltic andesite (55 wt% SiO2) from western Mexico. A close comparison between the experimental phase assemblages and their compositions, and the phenocryst assemblages of the lavas, is found in water saturated liquids, suggesting that the CO2 content was minimal in the fluid phase. Thus the historic lavas from Volcan Colima (with phenocrysts of orthopyroxene, augite… Expand
Hydrous phase equilibria of a Mexican high-silica andesite:A candidate for a mantle origin?
Abstract A group of Pleistocene-recent lavas, with 62 to 64% SiO2 and 5.6 to 3.5% MgO, have erupted along a linear fault system near the volcanic front of central Mexico. Not only is the compositionExpand
Experimental phase relations of a low MgO Aleutian basaltic andesite at XH2O = 0.7–1
We conducted melting experiments on a low MgO (3.29 wt.%) basaltic andesite (54.63 wt.% SiO2) from Westdahl volcano, Alaska, at XH2O = 0.7–1 and fO2 ~ Ni–NiO, at pressures = 0.1–180 MPa andExpand
The andesite aqueduct: perspectives on the evolution of intermediate magmatism in west-central (105–99°W) Mexico
Abstract Intermediate calc-alkaline magma (52–65% SiO2) in western-central Mexico is the focus of this paper, and the typically porphyritic andesites (57–65% SiO2) form large central volcanoes,Expand
A Hornblende Basalt from Western Mexico: Water-saturated Phase Relations Constrain a Pressure---Temperature Window of Eruptibility
Trachybasalt scoria from a cinder cone near the Mexican volcanic front contain phenocrysts of olivine with chromite inclusions, apatite, augite and hornblende, with microphenocrysts of plagioclase.Expand
Storage conditions and evolution of andesitic magma prior to the 1991–95 eruption of Unzen volcano: Constraints from natural samples and phase equilibria experiments
The compositions of homogenized melt inclusions trapped in plagioclase (Pl) microphenocrysts (40–200 μm length) from mafic enclaves within dacitic rocks erupted at Unzen volcano in 1991–95 wereExpand
Amphibole stability in primitive arc magmas: effects of temperature, H2O content, and oxygen fugacity
The water-saturated phase relations have been determined for a primitive magnesian andesite (57 wt% SiO2, 9 wt% MgO) from the Mt. Shasta, CA region over the pressure range 200–800 MPa, temperatureExpand
Storage conditions of Bezymianny Volcano parental magmas: results of phase equilibria experiments at 100 and 700 MPa
The crystallization sequence of a basaltic andesite from Bezymianny Volcano, Kamchatka, Russia, was simulated experimentally at 100 and 700 MPa at various water activities (aH2O) to investigate theExpand
Amphibole crystallization from a water-saturated andesite melt: Experimental data at P = 2 kbar
This paper reports the results of an experimental investigation of the influence of iron oxidation state in the water-saturated andesite melt of Shiveluch Volcano (Kamchatka) on amphiboleExpand
Experimental study of a low-alkali tholeiite at 1–5 kbar: optimal condition for the crystallization of high-An plagioclase in hydrous arc tholeiite
We conducted melting experiments on a low-alkali tholeiite (SiO2 ~52 wt%, MgO ~6.5 wt%, CaO/Na2O~4.4, Al2O3/SiO2 ~0.33) under both H2O-undersaturated and H2O-saturated conditions to investigate theExpand
Phase equilibrium of a high ‐ SiO 2 andesite at f 02 = RRO : implications for Augustine Volcano and other high ‐ f 02 arc andesites
Understanding the impact of magmatic plumbing systems on explosive volcanic activity is important for hazard management. This study describes phase equilibria experiments using a high-silica andesiteExpand


Water-saturated and undersaturated melting relations in a Paricutin andesite and an estimate of water content in the natural magma
Phase relations have been determined for a Paricutin Volcano andesite at pressures to 10 kilobars and for H2O contents in the melt of 2 to 10 weight percent. Runs were made under H2O-saturated andExpand
The May 18, 1980, eruption of Mount St. Helens: 1. Melt composition and experimental phase equilibria
The Mount St. Helens, May 18 pumice is a dacite containing 60% glass by weight and phenocrysts of plagioclase, orthopyroxene, amphibole, titaniferous magnetite, and ilmenite. The glass is uniform inExpand
Melting Relations of Basalt with Equilibrium Water Pressure Less Than Total Pressure
Equilibrium H,O pressure (POH.O) was fixed at values less than total pressure (PT) in melting experiments on mixtures of 1921 Kilauea tholeiite, H,O, and CO, (58-5 mole per cent H,O, 41-5 mole perExpand
Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism
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. ExperimentalExpand
The May 18, 1980, eruption of Mount St. Helens: 3. Stability and chemistry of amphibole in the magma chamber
Additional experiments have been done with the May 18, 1980, Mount St. Helens dacite and a more mafic, October 1980 sample to resolve questions concerning amphibole stability and dissolved volatilesExpand
Crystallization and Fractionation Trends in the System Andesite-H2O-CO2-O2 at Pressures to 10 Kb
Phase relations of a Mount Hood andesite, which has the composition of an average orogenic andesite, have been determined as a function of O 2 fugacity at 1 atm and of H 2 O fugacity to pressures ofExpand
A magmatic geohygrometer: Application to Mount St. Helens and other dacitic magmas
Compositions of andesitic to dacitic melts in equilibrium with plagioclase, orthopyroxene, and clinopyroxene have been experimentally calibrated as a geohygrometer. Application to Melson's data onExpand
Plagioclase-melt equilibria in hydrous systems.
Although plagioclase is the most common minera! in crustal rocks, plagioclase-melt equilibrium relationships in hydrous silicate systems are poorly understood. This study is based on analyses of 54Expand
Slab-derived fluids and partial melting in subduction zones: insights from two contrasting Mexican volcanoes (Colima and Ceboruco)
Colima and Ceboruco are the only two historically active volcanoes in the western portion of the Mexican Volcanic Belt. Contrasts in eruptive style and mineralogy indicate that magmas from Colima areExpand
Quaternary minettes and associated volcanic rocks of Mascota, western Mexico: a consequence of plate extension above a subduction modified mantle wedge
Abstract Pleistocene-Holocene volcanism in the Jalisco block of western Mexico is confined to two conspicuous grabens, where potassic eruptives range from absarokites (48–52% SiO2) and minettesExpand