Geochemical and petrological insights into the tectonic origin of the Transmexican Volcanic Belt
Por:
Gómez-Tuena A., Mori L., Straub S.M.
Publicada:
1 ago 2018
Ahead of Print:
1 ene 2016
Categoría:
Earth and Planetary Sciences (miscellaneous)
Resumen:
The Transmexican Volcanic Belt (TMVB) is the magmatic expression of one
of the most complex convergent margins on the planet, and as such
constitutes a prime location for testing emerging hypotheses on arc
magma genesis and its influence on continental crust formation. By
coupling an extensive geochemical and petrological database with an
improved stratigraphic and geophysical framework, in this contribution
we will examine the compositional diversity of the TMVB from the
perspective of changes in subduction zone geometry and crustal
thickness, as well as within the context of more subtle tectonic
processes such as lithospheric foundering, slab detachment, fore-arc
subduction erosion, crustal relamination and diapiric exhumation. We
will illustrate that the compositional variability of mafic magmas
across the region is an inherited characteristic of a geochemically
enriched pre-subduction background mantle wedge, which has been variably
overprinted by diverse chemical fluxes released from the slab at
different thermal conditions. We will argue that the volumetrically
dominant intermediate magmas in Mexico - from andesite to dacite and
even some rhyolite - represent primary melts from hybrid slab and mantle
sources, with no perceptible compositional influences from the overlying
continental crust. These interpretations depart from conventional models
that invoke intra-crustal differentiation and contamination of basalt to
create intermediate magmas, and therefore have important implications to
understanding the genesis of global continents. (C) 2016 Elsevier B.V.
All rights reserved.
Filiaciones:
Centro de Geociencias, Universidad Nacional Autónoma de México, Querétaro 76230, Mexico
Facultad de Ingeniería, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
Lamont Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
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