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Article
The origin of high-Mg magmas in Mt Shasta and Medicine Lake volcanoes, Cascade Arc (California): higher and lower than mantle oxygen isotope signatures attributed to current and past subduction
We report the oxygen isotope composition of olivine and orthopyroxene phenocrysts in lavas from the main magma types at Mt Shasta and Medicine Lake Volcanoes: primitive high-alumina olivine tholeiite (HAOT), b...
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Article
Editorial
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Article
Silica and volatile-element metasomatism of Archean mantle: a xenolith-scale example from the Kaapvaal Craton
Textural evidence in a composite garnet harzburgite mantle xenolith from Kimberley, South Africa, suggests metasomatism of a severely melt-depleted substrate by a siliceous, volatile-rich fluid. The fluid reac...
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Article
Late Holocene hydrous mafic magmatism at the Paint Pot Crater and Callahan flows, Medicine Lake Volcano, N. California and the influence of H2O in the generation of silicic magmas
This paper characterizes late Holocene basalts and basaltic andesites at Medicine Lake volcano that contain high pre-eruptive H2O contents inherited from a subduction related hydrous component in the mantle. The...
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Article
Trace element abundances of high-MgO glasses from Kilauea, Mauna Loa and Haleakala volcanoes, Hawaii
We performed an ion-microprobe study of eleven high-MgO (6.7–14.8 wt%) tholeiite glasses from the Hawaiian volcanoes Kilauea, Mauna Loa and Haleakala. We determined the rare earth (RE), high field strength, a...
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Article
Melt/harzburgite reaction in the petrogenesis of tholeiitic magma from Kilauea volcano, Hawaii
We use the results of elevated pressure melting experiments to constrain the role of melt/mantle reaction in the formation of tholeiitic magma from Kilauea volcano, Hawaii. Trace element abundance data is com...
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Article
Hornblende gabbro sill complex at Onion Valley, California, and a mixing origin for the Sierra Nevada batholith
The steep crest of the Sierra Nevada, California, near Onion Valley, exposes natural cross sections through a mafic intrusive complex that formed as part of the Mesozoic Sierra Nevada batholith. Sheeted sills...
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Article
Experiments and models of anhydrous, basaltic olivine-plagioclase-augite saturated melts from 0.001 to 10 kbar
A new method for modeling fractional crystallization processes that involve olivine (ol), plagioclase (plag) and augite (aug) is presented. This crystallization assemblage is the major control on the chemical...
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Article
Evidence of hydrous differentiation and crystal accumulation in the low-MgO, high-Al2O3 Lake Basalt from Medicine Lake volcano, California
The late Pleistocene Lake Basalt of Medicine Lake volcano, California is comprised of variably porphyritic basalt and basaltic andesite flows and scoria. These eruptives are similar in composition and phenocry...
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Article
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. Experimental liquids are l...
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Article
Temperatures and H2O contents of low-MgO high-alumina basalts
Experimental evidence is used to estimate H2O contents in low-MgO high-alumina basalts (HABs) (<6 wt.% MgO) and basaltic andesites (BAs) (<5 wt.% MgO) that occur worldwide in magmatic arcs. Wholerock compositions...
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Article
Experimental and major element constraints on the evolution of lavas from Lihir Island, Papua New Guinea
The major element chemistry of SiO2-undersaturated arc lavas from Lihir Island, Papua New Guinea, and 1 atmosphere experiments on an alkali basalt from this island show complex polybaric fractionation affected th...
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Article
Experimental investigations of low-Ca pyroxene stability and olivine-pyroxene-liquid equilibria at 1-atm in natural basaltic and andesitic liquids
This paper reports experiments carried out at 1-atm under conditions of controlled oxygen fugacity, using natural andesites and andesite mixed with augite+synthetic pigeonite or augite+orthopyroxene. The exper...
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Article
Assimilation of granite by basaltic magma at Burnt Lava flow, Medicine Lake volcano, northern California: Decoupling of heat and mass transfer
At Medicine Lake volcano, California, andesite of the Holocene Burnt Lava flow has been produced by fractional crystallization of parental high alumina basalt (HAB) accompanied by assimilation of granitic crus...
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Article
Experimental petrology of normal MORB near the Kane Fracture Zone: 22°–25° N, mid-Atlantic ridge
Melting experiments carried out at 1-atm and at 2 kbar on mid-ocean ridge basalts dredged from the mid-Atlantic ridge near the Kane Fracture Zone (KFZ, 22° to 25° N. latitude) provide a basis for evaluating th...
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Article
The evolution of young silicic lavas at Medicine Lake Volcano, California: Implications for the origin of compositional gaps in calc-alkaline series lavas
At Medicine Lake Volcano, California, the compositional gap between andesite (57–62 wt.% SiO2) and rhyolite (73–74 wt.% SiO2) has been generated by fractional crystallization. Assimilation of silicic crust has al...
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Article
Fractionation of pyroxene-phyric MORB at low pressure: An experimental study
One-atmosphere melting experiments are used to assess the role of clinopyroxene in producing the compositional variations observed in mid-ocean-ridge basalts (MORBs) from the North Atlantic. Analog models of n...
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Article
Origin of calc-alkaline series lavas at Medicine Lake volcano by fractionation, assimilation and mixing: Corrections and clarifications
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Article
Use of FePt alloys to eliminate the iron loss problem in 1 atmosphere gas mixing experiments: Theoretical and practical considerations
Theoretical and practical considerations are combined to place limits on the iron content of an FePt alloy that is in equilibrium with silicate melt, olivine and a gas phase of known
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Chapter
Exsolution in Metamorphic Bytownite
It is not possible to investigate the exsolution in calcic plagioclases using synthetic materials and standard phase equilibria experiments. The kinetics of the exchange NaSi⇌CaAl involved in the unmixing are ...