A history of violence: magma incubation, timing and tephra distribution of the Los Chocoyos supereruption (Atitlán Caldera, Guatemala)

• Published in: Journal of quaternary science 2021-02, Vol.36 (2), p.169-179
• Main Authors: Cisneros de León, Alejandro, Schindlbeck‐Belo, Julie C., Kutterolf, Steffen, Danišík, Martin, Schmitt, Axel K., Freundt, Armin, Pérez, Wendy, Harvey, Janet C., Wang, Kuo‐Lung, Lee, Hao‐Yang
• Format: Article
• Language: English
• Subjects: (U–Th)/He; 238U–230Th disequilibrium; Age; Aggression; Calderas; Chronology; Crystallization; Eruptions; Geochronology; Magma; Markers; Oceans; Quaternary; tephrochronology; Zircon
• ISSN: 0267-8179; 1099-1417
• DOI: 10.1002/jqs.3265

ABSTRACT The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization 238U–230Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W‐Fall (130 +16/−14 ka) and I‐Fall eruptions (56 +8.2/−7.7 ka), which under‐ and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for >80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km3 is obtained (volcanic explosivity index VEI > 8), which confirms the LCY eruption as the first‐ever recognized supereruption in Central America.