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Revisiting the Holocene eruptive chronology of the Nevado Cayambe volcano, Ecuador

Pablo Samaniego 1, Francisco J. Vasconez2,3, Benjamin Bernard2, Nicole Vizuete1

  • Affiliations:  1 Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, IRD, OPGC, F-63000 Clermont-Ferrand, France 2 Instituto Geofísico, Escuela Politécnica Nacional, Ap. 17-01-2759, Quito, Ecuador 3 School of Earth Sciences, University of Bristol, BS8 IRJ, Bristol, UK

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 129

  • Programme No: 3.4.16

  • Theme 3 > Session 4

Abstract

Determining the eruptive chronology of the Northern Andean volcanoes is particularly challenging because their history of large eruptions separated by long periods of quiescence. Nevado Cayambe, a large ice-capped andesitic-dacitic volcanic centre in the Eastern Cordillera of the Ecuadorian Andes, exemplifies this complexity. Its eruptive chronology was initially outlined by Samaniego et al. (1998), who identified at least 23 eruptions during the last 4000 years. Holocene eruptive products at Nevado Cayambe include: (1) tephra fallout and surge deposits interlayered with organic-rich paleosoils, outcropped on the upper flanks of the volcano; and, (2) large pyroclastic density currents (PDC) deposits primarily exposed in the deep glacial valleys on the volcano's north-eastern flank. These deposits are associated with summit dome growth and subsequent collapses. Building on new field data, over 40 radiocarbon age determinations, and historical chronicles, we identified nine eruptive episodes since 4400 cal BP. A Bayesian approach, integrating radiometric and stratigraphic data, constrains the duration of each episode to 200-300 years, separated by quiescent intervals lasting several centuries. This refined chronology reveals correlations between tephra deposits and valley-ponded PDC deposits, suggesting that eruption magnitudes have increased over the past four millennia. Notably, the San Marcos episode (1280 - 1660 CE) produced significant valley-ponded PDC and surge deposits that impacted the upper north-western flank. Spanning the pre-Columbian and early colonial periods, this episode represents the most significant recent activity of Nevado Cayambe.