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
Official URL: http://www.tandf.co.uk/journals/titles/00206814.asp
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.
|Uncontrolled Keywords:||El Chichón volcano; Magmatisme; Geochemical; Mexico|
|Subjects:||Sciences > Geology > Petrology|
|Deposited On:||05 Dec 2011 14:34|
|Last Modified:||05 Dec 2011 14:34|
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