73 Using Volcanic Deposits to Help Us Understand Volcanic and Magmatic Processes (Posters)

This session invites presentations that leverage volcanic deposits to reconstruct magmatic and eruptive processes. We welcome contributions from field and experimental volcanology, petrology, geochemistry, thermodynamics, and fluid mechanics, ranging from the landform to nanoscale.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Chemical-Temporal Complexity in the Eruptive Products of Xitle Volcano, Mexico: A Window into a Complex Monogenetic Magmatic System and the Underlying Mantle Wedge

Paper number: 73-2
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Monogenetic volcanoes are the most common volcanic features on Earth and despite their usually small sizes they can pose significant hazards, especially near populated areas, highlighting the importance of understanding their eruptive history and geochemical evolution. Xitle Volcano, a ~1600-year-old monogenetic cone on the southern edge of Mexico City and the central TMVB, destroyed several pre-Hispanic settlements during its eruption. Xitle eruptive products exhibit complex chemical-temporal variations which may result from either fractional crystallization and crustal assimilation (AFC) of a single magma batch or magma recharge with mixing and/or mingling of multiple melts from a heterogeneous mantle source. To investigate this, we present major and trace element data and Sr–Nd–Pb–Os isotopes from 40 samples capturing the entire duration of the eruption, integrated with new stratigraphic mapping and petrologic observations.

 

Variations in Sr-Nd-Pb-Os isotopic signatures occur throughout the eruption sequence but show no correlation with SiO2 or Mg#, arguing against simple AFC processes. This interpretation is also supported in Os–Sr–Pb isotope space and MELTS modeling. Alternatively, distinct geochemical and isotopic groupings in major and trace elements, along with petrographic evidence such as magma mingling textures and disequilibrium features in olivine crystals, support a model involving magma recharge and mixing among at least three compositionally and isotopically distinct magma batches. Magma Chamber Simulator (MCS) modeling confirms this scenario, successfully reproducing the observed compositions through successive magma recharge events. These magma batches originated from a heterogeneous mantle wedge metasomatized by variable slab-derived fluids/melts dominated by subducted terrigenous sediment. Osmium isotope systematics imply serial fluid addition from the slab, along with progressive melt depletion and oxidation of the mantle wedge, as likely processes governing mantle wedge evolution beneath Xitle.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412605

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