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El Chichón Volcano (Chiapas Volcanic Belt, Mexico) Transitional Calc-Alkaline to Adakitic-Like Magmatism: Petrologic and Tectonic Implications

Ignacio San José, Cristina de and Castiñeiras García, Pedro and Márquez González, Álvaro and Oyarzun Muñoz, Roberto and Lillo Ramos, F. Javier and López Ruiz-Labranderas, Iván (2003) El Chichón Volcano (Chiapas Volcanic Belt, Mexico) Transitional Calc-Alkaline to Adakitic-Like Magmatism: Petrologic and Tectonic Implications. International geology review, 45 . pp. 1020-1028. ISSN 0020-6814

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Abstract

The rocks of the 1982 eruption of El Chichón volcano (Chiapas, Mexico) display a series of
geochemical and mineralogical features that make them a special case within the NW-trending
Chiapas volcanic belt. The rocks are transitional between normal arc and adakitic-like trends. They
are anhydrite-rich, and were derived from a water-rich, highly oxidized sulfur-rich magma, thus very
much resembling adakitic magmas (e.g., the 1991 Pinatubo eruption). We propose that these rocks
were generated within a complex plate tectonic scenario involving a torn Cocos plate (Tehuantepec
fracture zone) and the ascent of hot asthenospheric mantle. The latter is supported by an outstanding
negative S-wave anomaly widely extending beneath the zone, from 70 to 200 km in depth. The adakitic-
like trend would be derived from the direct melting of subducting Cocos plate, whereas the
transitional rocks would have resulted from the mixing of two poles, one reflecting a mantle source,
and the other, the already mentioned adakitic melts. The basaltic source would also account for the
high sulfur content and 34S values of the El Chichón system (about +5.8), as result of a contribution
of SO2 in fluids released from an underlying mafic magma.


Item Type:Article
Uncontrolled Keywords:El Chichón volcano; Magmatisme; Geochemical; Mexico
Subjects:Sciences > Geology > Petrology
ID Code:14023
Deposited On:05 Dec 2011 13:34
Last Modified:05 Dec 2011 13:34

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