Reconstruction of the magmatic system from the 1870 eruption of Ceboruco, Mexico: Implications for magma residence time and ascent dynamics.
Abstract
Ceboruco is a stratovolcano in the westernmost portion of the Trans-Mexican Volcanic Belt. Its crustal basement, similar to neighboring Volcán de Colima, features a homonymous asymmetric graben within the Tepic-Zacoalco rift and the Rivera-North America subduction zone. Ceboruco is bounded by the Mid-American Trench on the west, at 190 km, and the south, at 300 km. The slab is found at a depth >100 km from which a steep slab angle of 45-50° is inferred. Ceboruco eruptive products tend to be less hydrated and oxidized, yet have more abundant incompatible elements compared to Volcán de Colima, which lies closer to the trench. Ceboruco last erupted during 1870-5 CE exhibiting both explosive and effusive activity. The latter resulted in a 7.5 km long dacitic lava flow with an associated plug dome and a larger dome complex. During its history, its output has been dominated by andesitic lava flows. However, more evolved melts, like the most recent dacite, generally are produced when eruption recurrence intervals are longer. Geophysical surveys locate the magma chamber for the 1870 eruption and past events at depths around 1 km below mean sea level, whilst the chemical signature suggests a source region located in the mantle wedge. We present mineral and rock compositions from various locations of the 1870-5 event to evaluate how changes in crystallinity relate to possible changes in melt composition during the course of the eruption. This study reconstructs the subsurface conditions for the 1870-5 magma with phase equilibrium modeling tools such as MELTS and plagioclase-melt thermobarometers to understand whether magma stalled and digested deeper crust before its ascent to the shallow magma chamber.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V23E0224B
- Keywords:
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- 1036 Magma chamber processes;
- GEOCHEMISTRY;
- 1199 General or miscellaneous;
- GEOCHRONOLOGY;
- 7299 General or miscellaneous;
- SEISMOLOGY;
- 8439 Physics and chemistry of magma bodies;
- VOLCANOLOGY