Geology and radiometric dating of Quaternary monogenetic volcanism in the western Zacapu lacustrine basin (Michoacán, México): implications for archeology and future hazard evaluations

Abstract

The Zacapu lacustrine basin is located in the north-central part of the Michoacán-Guanajuato volcanic field (MGVF), which constitutes the west-central segment of the Trans-Mexican Volcanic Belt. Geological mapping of a 395 km 2 quadrangle encompassing the western margin of the basin, 40 Ar/ 39 Ar and 14 C radiometric dating, whole-rock chemical and petrographic analyses of volcanic products provide information on the stratigraphy, erupted volumes, age, and composition of the volcanoes. Although volcanism in the MGVF initiated since at least 5 Ma ago, rocks in the western Zacapu lacustrine basin are all younger than ~2.1 Ma. A total of 47 volcanoes were identified and include 19 viscous lava flows (~40 vol.%), 17 scoria cones with associated lava flows (~36 vol.%), seven lava shields (~15 vol.%), three domes (~6 vol.%), and one maar (~2 vol.%). Erupted products are dominantly andesites with 42 km 3 (~86 vol.%) followed by 4 km 3 of dacite (~8 vol.%), 1.4 km 3 of basaltic trachyandesite (~3 vol.%), 1 km 3 of basaltic andesite (~2 vol.%), and 0.14 km 3 of rhyolite (~0.3 vol.%). Eruptive centers are commonly aligned ENE-WSW following the direction of the regional Cuitzeo Fault System. Over time, the high frequency of eruptions and consequent accumulation of lavas and pyroclastic materials pushed the lake's shore stepwise toward the southeast. Eruptions appear to have clustered through time. One cluster occurred during the Late Pleistocene between ~27,000 and 21,300 BC when four volcanoes erupted. A second cluster formed during the Late Holocene, between ~1500 BC and ~AD 900, when four closely spaced monogenetic vents erupted forming thick viscous 'a'a to blocky flows on the margin of the lacustrine flats. For still poorly understood reasons, these apparently inhospitable lava flows were attractive to human settlement and eventually became one of the most densely populated heartlands of the pre-Hispanic Tarascan civilization. With an average eruption recurrence interval of ~900 years during the Late Holocene the western Zacapu lacustrine basin is one of the most active areas in the MGVF and should hence be of focal interest for regional volcanic risk evaluations.Keywords Zacapu basin . Michoacán-Guanajuto volcanic field . Quaternary . Monogenetic cluster . Radiocarbon . 40 Ar/ 39 Ar dating . Malpaís * Nanci Reyes-Guzmán

Testing Web Mapping and Active Learning to Approach Lidar Data

“…Compared with its contemporaneous neighbors, however, the site remains understudied. El Infiernillo is located on the western front of the Zacapu Malpaís, on a lava flow dating to 3200 ± 30 BP (Reyes-Guzmán et al 2018). Scholars have described the built environment at the site on several occasions (Forest 2014; Michelet 1998, 2008; Pereira and Forest 2010), and it is considered characteristic of Middle Postclassic urbanism in the region.…”

Las Cabras volcano, Michoacán-Guanajuato Volcanic Field, México: Topographic, climatic, and shallow magmatic controls on scoria cone eruptions

“…Scoria cones and other monogenetic vents are abundant along the TMVB and form large fields, the largest of these being the Michoacán-Guanajuato Volcanic Field, hereafter referred to as MGVF (Figure 1; Hasenaka and Carmichael, 1985;Connor, 1990). The MGVF includes >1100 small-to-medium sized Quaternary volcanic edifices, at least 20 of which formed in the Holocene (Hasenaka and Carmichael, 1985;Guilbaud et al, 2009;Chevrel et al, 2016;Mahgoub et al, 2017;Osorio-Ocampo et al, 2018;Reyes-Guzmán et al, 2018;Ramírez-Uribe et al, 2019;Larrea et al, 2019b;Macías and Arce, 2019). These studies report that volcanoes in the MGVF are dominantly scoria cones with lava flows and medium-sized shields, with some viscous flows without cones at source, domes, and rare maars.…”

“…Here, we present results from the detailed study of Las Cabras volcano, a breached scoria cone with several lava lobes located in the central part of the MGVF (Figure 1) near the margin of a fault-bounded lake basin, and close to a cluster of Holocene vents (Siebe et al, 2014;Reyes-Guzmán et al, 2018). This volcano is morphologically similar to many other young scoria cones in the MGVF, yet its products display peculiar sedimentary and textural features that motivated this study.…”

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

“…In addition to a few dozen large stratovolcanoes and calderas, the Trans-Mexican Volcanic Belt (TMVB) includes several 1000 small-to medium-sized volcanoes whose ages range from early-Pleistocene to Holocene (Guilbaud et al, 2011(Guilbaud et al, , 2012Hasenaka and Carmichael, 1985;Reyes-Guzmán et al, 2018;Siebe et al, 2005Siebe et al, , 2004. In the eastern part of the TMVB, the Serdán-Oriental basin hosts a large number of vents encompassing the entire range of monogenetic volcano types encountered in the TMVB (maars, tuff rings/cones, scoria cones, lava flows, domes, and shield volcanoes; Figure 1).…”