Stratigraphy and radiocarbon ages of late-Holocene Las Derrumbadas rhyolitic domes and surrounding vents in the Serdán-Oriental basin (Mexico): Implications for archeology, biology, and hazard assessment
The Serdán-Oriental lacustrine basin in the eastern part of the Trans-Mexican Volcanic Belt holds a volcanic field of >30 monogenetic vents. Among them, the ~1000-m-high, ~11 km3 Las Derrumbadas rhyolite twin domes dominate the interior of the basin and are surrounded by smaller scoria cones, lava flows, shields, tuff rings, and maars. Of interest in this area are rare endemic species encountered in some of the maar lakes, as well as the large number of pre-Hispanic archeological sites indicating that the lacustrine environment became attractive as a dwelling hub during the late Holocene. We conducted a stratigraphic and radiocarbon dating study to reconstruct the volcanic history, assess the impact of past eruptions on the environment and pre-Hispanic populations, and evaluate future volcanic hazards. Accordingly, at least 10 volcanoes were identified to be < 25,000 BC of which eight are Holocene in age (Alchichica, Tecuitlapa, Atexcac, Cerro El Brujo, Tepexitl, Aljojuca, Derrumbadas, Piedras Negras). Hence, the central part of the Serdán-Oriental basin should be considered potentially active and new eruptions are likely to occur in the future. Furthermore, we show that the ~AD 20 Las Derrumbadas eruption is one of the most voluminous silicic effusive eruptions during the Holocene worldwide. This eruption possibly triggered a migration of human populations from dispersed rural hamlets in the central part of the basin toward fewer larger urban sites (e.g. Cantona) at its margins. Finally, the young ages of the maars imply that the unique biodiversity of their crater lakes must have developed over remarkably short timescales.
