Skip to content

Magma mixing in a dacitic plumbing system of Citlaltépetl volcano around ∼4 kyr BP, eastern Trans-Mexican Volcanic Belt

1José Luis Arce, J.L., 2José Luis Macías, 3Rafael Torres-Orozco, 1Delphine Sourisseau, 4José Juan Carrillo-Mondragón, 5Mireya González-Herrera, 2Denis Ramón Avellán

  • Affiliations: 1Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria Coyoacán, Ciudad de México, México, 2Instituto de Geofísica, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Morelia, Michoacán, México, 3Centro de Ciencias de la Tierra, Universidad Veracruzana, Xalapa, Veracruz, México, 4Posgrado en Ciencias de la Tierra, UNAM, Ciudad Universitaria Coyoacán, Ciudad de México, México, 5Escuela Superior de Ingeniería y Arquitectura, Instituto Politécnico Nacional, Ticomásn, Ciudad de México, México.

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 178

  • Programme No: 1.8.9

  • Theme 1 > Session 8

Abstract

Magma mixing is a common mechanism at the active Citlaltépetl volcano (5,650 above sea level), located in the eastern Trans-Mexican Volcanic Belt. We document two explosive eruptions (Avalos ~4 kyr BP and Jamapa <5 kyr BP) that generated pyroclastic density currents. The Jamapa Vulcanian-type eruption generated a scoria flow deposit, constituted by andesitic scoria (58 wt. % of SiO2), dacitic pumice (63 wt. % of SiO2), and banded scoriaceous fragments. The mineral assemblage is made of plag + opx + cpx + amph + /- Fe-Ti oxides in different proportions with disequilibrium textures. Plagioclase and matrix glass compositions are heterogeneous suggesting mixing between andesitic and dacitic magmas. Whereas Avalos is related to a dome-destruction event that produced a block-and-ash flow deposit of homogeneous dacitic composition (63-64 wt. % of SiO2). The mineral assemblage is made of plag + cpx + opx + amph +/- Fe-Ti oxides. However, plagioclase and matrix glass compositions are also heterogeneous suggesting a mixing between two magmas. Pressure and temperature estimations for both eruptions point to a relatively shallow dacitic reservoir (~190 MPa and ~880°C) continuously rejuvenated by hotter mafic melts coming from deeper reservoirs (~390 MPa and ~980ºC). The Jamapa event likely occurred shortly after the contact between the mafic and felsic magmas, whereas the Avalos eruption occurred after a longer period of time since the mixing event. Our results suggest the presence of a shallower felsic magma reservoir feeded by deeper mafic magmas stored ≥ 14 km below Citlaltépetl volcano.