Abrupt changes in magma generation processes along the Central American arc in southeastern Guatemala: flux-dominated melting near the base of the wedge to decompression melting near the top of the wedge
Article Abstract:
Magma associated with behind-the-front volcanism (BVF) in southeastern Guatemala is formed by decompression melting near the top of the crustal wedge. BVF magma formation is partially or wholly removed from the magma formation on the volcanic front due a crustal extension behind the front. The major elements and radiogenic trace elements present in this magma are different from other local magmas due to less melting in the source, less fractionization during magmatic ascent and storage in the crust, and less material contributed from the subducted part of the Cocos plate.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1995
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Quaternary volcanism neart the Valley of Mexico: implications for subduction zone magmatism and the effects of crustal thickness variations on primitive magma compositions
Article Abstract:
Issues concerning high-Mg basalts and basaltic andesites from the subduction-related volcanic arc called Mexican Volcanic Belt which abounds with magmas with primitive compositions were addressed. A novel petrologic and geochemical data for volcanic rocks in the Chichinautzin volcanic field in central Mexico which is near Mexico City were presented. The primitive magma compositions from the region were compared with those from other parts of the arc with thinner crust. Valuable probes were provided by primitive magmas for evaluating subduction-related mantle enrichment.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1999
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The Aurora volcanic field, California-Nevada: oxygen fugacity constraints on the development of andesitic magma
Article Abstract:
The Aurora volcanic field of California-Nevada exposes a variety of high-K lava types from basalt through dacite. The lavas exhibit a perfect calc-alkaline differentiation trend. The oxygen fugacity values of the lavas fall within - 0.4 and + 2.4 log units of the Ni-NiO buffer. A model that explains the evolution of andesite magmas suggests that closed-system equilibrium crystallization of a basalt was followed by repeated equilibrium partial melting. This produced a calc-alkaline evolved liquid which has oxygen fugacity similar to the initial basalt.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1996
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