Arc-related subalkaline magmas at the Los Tuxtlas volcanic complex and its relation to the tectonic evolution in southern México

The Los Tuxtlas Volcanic Complex is an isolated volcanic province that emerges on the coastal plain of the Gulf of Mexico in southern Veracruz state. The NW sector is associated with a monogenetic field composed of hundreds of scoria cones and explosion craters or maars, while the SE area is formed by the Santa Marta ridge, a mountain range of four volcanic edifices with an NW-SE orientation. These volcanic manifestations overlie fissural lavas in the SW and in small outcrops on the coastline. The emplacement of magmas was controlled by the development of a pull-apart basin during three episodes called Montepío-El Vigía (7–1.5 Ma), Santa Marta (1–0.5 Ma), and San Martín Tuxtla (50 ka to present). The most outstanding characteristic of this volcanic complex is the coexistence of two different geochemical signatures, attributed to a mafic pulse caused by a slab detachment propagation since the late Miocene. The origin of the LTVC magmas has been commonly associated with an enriched OIB-type mantle modified by subduction components and continental crust assimilation. Based on major and trace element geochemical data, we identified the petrogenetic processes involved in the origin of the LTVC magmas. Our results support the idea that subalkaline magmas of Santa Marta magmatic stage originated from a spinel peridotite source mantle and evolved by crystal fractionation with the incorporation of subduction sediments. In Montepío-El Vigía and San Martín Tuxtla stages, magmas originated from a garnet-spinel peridotite mantle interacted with the lithospheric mantle resulting in an enriched OIB-like garnet peridotite mantle. In these two stages, magmas evolved by prolonged crystal fractionation with minor influence of subduction fluids.