A 550-year-old Plinian eruption at El Chichón Volcano, Chiapas, Mexico: Explosive volcanism linked to reheating of the magma reservoir

• Published in: Journal of Geophysical Research. B. Solid Earth 2003-12, Vol.108 (B12), p.ECV3.1-n/a
• Main Authors: Macías, J. L., Arce, J. L., Mora, J. C., Espíndola, J. M., Saucedo, R., Manetti, P.
• Format: Article
• Language: English
• Subjects: Crystalline rocks; Earth sciences; Earth, ocean, space; El Chichón Volcano; Engineering and environment geology. Geothermics; Exact sciences and technology; Holocene; Igneous and metamorphic rocks petrology, volcanic processes, magmas; magma mixing; Marine and continental quaternary; Mexico; Natural hazards: prediction, damages, etc; Plinian eruption; Surficial geology
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2003JB002551

Some 550 years ago (1320–1433 A.D.), a powerful Plinian eruption at El Chichón Volcano in southern Mexico produced a widespread pumice fall deposit. We subdivided the deposit into three parts on the basis of structural and textural characteristics, pumice lithology and density, granulometry, and petrologic‐geochemical attributes. The deposit covers an area of 1500 km2 within the 1‐cm isopach and has a minimum estimated bulk volume of 2.8 km3 (1.1 km3 dense rock equivalent (DRE)); its eruptive column reached an altitude of ∼31 km. Consideration of field evidence, the presence and nature of mafic enclaves, and chemical data strongly suggest that the 550 year B.P. eruption is linked with the intrusion of a high‐temperature basaltic magma into preexisting but stagnated trachyandesitic magma beneath El Chichón. Thorough mixing of the two magmas produced a compositionally uniform hybrid trachyandesite magma (average SiO2 55.3 wt %), which subsequently underwent crystal growth and gas exsolution, ultimately overpressurizing the zoned magmatic system to erupt explosively. On the basis of El Chichón's known eruptive history, the intrusion‐mixing event occurred sometime after the 900 year B.P. eruption. The hybrid magma had a preeruption temperature of 820–830°C and was water undersaturated (5–6 wt % H2O) at pressures of ∼2–2.5 kbar.