Trenchward Plio-Quaternary volcanism migration in the Trans-Mexican Volcanic Belt: the case of the Sierra Nevada range.

The Miocene–Quaternary Trans-Mexican Volcanic arc is thought to have grown southwards (i.e. trenchward) since the Pliocene. This theory is mainly supported by roughly N–S-directed polygenetic volcanic ranges along which volcanic activity migrates southwards with time. We investigated the eruptive history of one of these ranges, the Sierra Nevada (east boundary of Mexico City basin), by compiling literature ages and providing new K–Ar dates. Our K–Ar ages are the first ones for the northernmost Tláloc and Telapón volcanoes and for the ancestral Popocatépetl (Nexpayantla). The obtained ages reveal that the four stratovolcanoes forming the range worked contemporaneously during most of the Middle to Late Pleistocene. However, taking into account the onset of the volcanic activity, a southward migration is evidenced along the Sierra Nevada: volcanism initiated at its northern tip at least 1.8 Ma ago at Tláloc volcano, extended southwards 1 Ma ago with Iztaccíhuatl and appeared at its southern end 329 ka ago with the Nexpayantla cone. Such a migration would be most probably primarily driven by Cocos slab roll-back and steepening rather than by regional crustal tectonics, which played a secondary role by controlling the apparent alignment of the volcanoes. [ABSTRACT FROM PUBLISHER]