Geochemistry, petrogenesis, and tectonic setting of the Los Tuxtlas Volcanic Field, Mexico

We present new major and trace element geochemical data, including the rare-earth elements (REE), platinum group elements and Au, and combine them with the publi- shed information to constrain the highly debated origin of magmas in the Los Tuxtlas Volcanic Field (LTVF) of the Late Miocene to historic age. The LTVF magmas originated in the garnet-bearing mantle as confirmed from the partial melting models of the REE. The mantle-derived magmas may have subsequently undergone fractional crystallization of mainly olivine. The controversial tectonic setting of the LTVF was solved by log-ratio transformed major as well as combined major and trace element data as a continental strike-slip fault setting during the Miocene–Pliocene. During the Pleistocene to Holocene, the more numerous samples having only major elements alone indicated the continental strike-slip fault setting, whereas the lesser number of samples having combined major and trace elements were more consistent with the continental extension. Importantly, no geochemical evidence for the involvement of the subducting slab in the magma genesis of the LTVF could be inferred. The inferences presented in this work were consistent with the entirety of geological, geochemical, and geophysical evidence. The multidimensional models also showed that the monogenetic volcanic field of the Xalapa region of the easternmost part of the Mexican Volcanic Belt represents a continental extension setting.

Citation:

Surendra P. Verma, Héctor López-Loera, Konduri S. V. Subramanyam, Chakravadhanula Manikyamba;  Geological Journal. 2020;1–17; DOI: 10.1002/gj.3918