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

Abstract

[1] 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 km 2 within the 1-cm isopach and has a minimum estimated bulk volume of 2.8 km 3 (1.1 km 3 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 SiO 2 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 % H 2 O) at pressures of $2-2.5 kbar.

Thermal and rheological controls on the formation of mafic enclaves or banded pumice

“…Second, hybrid magmas are commonly erupted at arc volcanoes. These magmas often show clear mixing trends between mafic and silicic end members, can sometimes comprise volumes [1 km 3 , and are often homogenized such that no macroscopic evidence (e.g., enclaves or banding) exists to record mixing (e.g., Browne et al 2006;Macias et al 2003;Huber et al 2009). In such magmas, isotopic and chemical zoning of phenocrysts may be the only evidence of mixing events (Tepley et al 1999(Tepley et al , 2000Browne et al 2006;Andrews et al 2008).…”

Pedosediments of karstic sinkholes in the eolianites of NE Yucatán: A record of Late Quaternary soil development, geomorphic processes and landscape stability

“…Although SAF of free-lime residue, Rendzinas and fills are similar, Zr/Ti has smaller values, reflecting its minor influence in soil chemical composition. It seems that volcanic materials from el Chichón (Espíndola et al, 2000;Macías et al, 2003;Andrews et al, 2008) are closely related to soils and pedosediments as it is evident by Zr/Ti values (Fig. 5b); rocks from the Maya Block of central Guatemala (Ortega, 2005), partially the Quaternary loess from North America (Taylor et al, 1983) and the Sahara dust (Moreno et al, 2006) could also have some minor contribution.…”

“…Rendzinas (Q4 and Akumal) and lime-free residue, are of similar contents to those of the fills. On the contrary, volcanic materials composition from Central America volcanoes (Milionis, 1987), El Chichón, Mexico (Espíndola et al, 2000;Macías et al, 2003;Andrews et al, 2008) as well as sediments from other potential sources, such as Quaternary loess from North America (Taylor et al, 1983), Sahara dust (Moreno et al, 2006) and from plutonicmetamorphic complexes of the Maya Block (Ortega, 2005), have larger percentages of silica and smaller concentrations of alumina.…”

Hazard estimates for El Chichón volcano, Chiapas, México: a statistical approach for complex eruptive histories

“…Although Table 1. Volcanic Explosivity Indexes and ages of known eruptions with magnitude VEI≥3 of El Chichón volcano from different sources Tilling et al, 1984;Espíndola et al, 2000;Macías et al, 1993Macías et al, , 2003Macías et al, , 2007Macías et al, , 2008. The dates are averages of the reported radiometric age in years before the last (1982) eruption.…”