Geochemistry of the subducting Cocos plate and the origin of subduction-unrelated mafic volcanism at the volcanic front of the central Mexican Volcanic Belt

Magmatic processes have usually been identified and evaluated using qualitative or semiquantitative geochemical or isotopic tools based on a restricted number of variables. However, a more complete and quantitative view could be reached applying multivariate analysis, mass balance techniques, and statistical tests. As an example, in this work a statistical and quantitative scheme is applied to analyze the geochemical features for the Sierra de las Cruces (SC) volcanic range (Mexican Volcanic Belt). In this locality, the volcanic activity (3.7 to 0.5 Ma) was dominantly dacitic, but the presence of spheroidal andesitic enclaves and/or diverse disequilibrium features in majority of lavas confirms the operation of magma mixing/mingling. New discriminant-function-based multidimensional diagrams were used to discriminate tectonic setting. Statistical tests of discordancy and significance were applied to evaluate the influence of the subducting Cocos plate, which seems to be rather negligible for the SC magmas in relation to several major and trace elements. A cluster analysis following Ward’s linkage rule was carried out to classify the SC volcanic rocks geochemical groups. Finally, two mass-balance schemes were applied for the quantitative evaluation of the proportion of the end-member components (dacitic and andesitic magmas) in the comingled lavas (binary mixtures).

Download Full-text

Alkaline Lavas in the Volcanic Front of the Western Mexican Volcanic Belt: Geology and Petrology of the Ayutla and Tapalpa Volcanic Fields

Journal of Petrology ◽

10.1093/petrology/42.12.2333 ◽

2001 ◽

Vol 42 (12) ◽

pp. 2333-2361 ◽

Cited By ~ 36

Author(s):

K. RIGHTER

Keyword(s):

Volcanic Belt ◽

Volcanic Front ◽

Mexican Volcanic Belt ◽

Volcanic Fields

Download Full-text

Late-Pleistocene to precolumbian behind-the-arc mafic volcanism in the eastern Mexican Volcanic Belt; implications for future hazards

Journal of Volcanology and Geothermal Research ◽

10.1016/s0377-0273(01)00316-x ◽

2002 ◽

Vol 115 (1-2) ◽

pp. 179-205 ◽

Cited By ~ 46

Author(s):

Lee Siebert ◽

Gerardo Carrasco-Núñez

Keyword(s):

Late Pleistocene ◽

Volcanic Belt ◽

Mexican Volcanic Belt ◽

Mafic Volcanism

Download Full-text

CONTEMPORANEOUS ERUPTIONS OF CALC-ALKALINE AND ALKALINE MAGMAS ALONG THE VOLCANIC FRONT OF THE MEXICAN VOLCANIC BELT

Geofísica Internacional ◽

10.22201/igeof.00167169p.1985.24.1.1071 ◽

1985 ◽

Vol 24 (1) ◽

pp. 203-216

Author(s):

J. F. Luhr ◽

I. S. E.Carmichael.

Keyword(s):

Volcanic Belt ◽

Volcanic Front ◽

Calc Alkaline ◽

Mexican Volcanic Belt ◽

Alkaline Magmas

De acuerdo con los modelos generales para los arcos volcánicos relacionados con la subducción, las composiciones del magma se hacen progresivamente más ricas en Kâ‚‚0 y los elementos incompatibles, a medida que aumentan la distancia desde la trinchera y el frente volcánico, y la profundidad de la zona de Benioff. Los magmas típicos de los arcos son característicamente normativos de hiperesteno y cuarzo. Los basaltos alcalinos normativos de nefelino se supone que son expulsados, si acaso, sólo a grandes distancias de la trinchera. Sin embargo, a lo largo del frente del Eje Volcánico Mexicano han hecho erupción magmas básicos alcálicos hídricos, normativos de nefelino en dos diferentes sitios durante el Período Cuaternario Tardío: en el graben del sur de Colima y en el campo volcánico del sur de Michoacán y Guanajuato. En ambos lugares hicieron erupción contemporáneamente magmas calcalcalinos normativos de hiperesteno y cuarzo, característicos de los frentes volcánicos. Estas secuencias contrastantes de magmas no pueden ser correlacionadas mediante un mecanismo simple; parecen registrar distintos episodios de fusión dentro del manto superior.

Download Full-text