Skip to content

Volcano-sedimentary interactions in a Plio-Pleistocene intra-arc basin of the Patagonian Andes: fluvial responses to explosive and effusive eruptions

Joaquín Bucher 1; Cecilia del Papa2; Irene Hernando1

  • Affiliations: 1 Centro de Investigaciones Geológicas (CIG), CONICET-UNLP, Diagonal 113 No. 275, B1904DPK La Plata, Argentina. 2 Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), UNC-CONICET, Av. Vélez Sarfeld 1611, X5016GCA Córdoba, Argentina. 

  • Presentation type: Talk

  • Presentation time: Tuesday 14:30 - 14:45, Room R280

  • Programme No: 3.5.6

  • Theme 3 > Session 5

Abstract

Understanding how volcanic eruptions influence the dynamics of a sedimentary system is challenging and has motivated extensive research. These processes remain incompletely understood, emphasizing the need for integrative interdisciplinary studies. Volcano-sedimentary systems exhibit unique characteristics, influenced by factors such as the type and volume of the volcanic activity (explosive vs. effusive), sedimentary system attributes, and geotectonic settings (e.g., transtensional, extensional, compressional regimes). This study presents preliminary findings from the Plio-Pleistocene Hualcupen succession, located in the intra-arc region of the Southern Volcanic Zone of the Andes, Argentina. Two distinct fluvial responses to explosive and effusive eruptions were identified and compared: (a) explosive eruptions associated with a scoria cone generation led to increased sediment supply, resulting in widened, shallower channels with sheet-like flows following substantial pyroclastic input; (b) effusive lava flows filled and leveled pre-existing channels, triggering channel avulsion, subsequent periods of fluvial incision, and the development of deeply incised channels. Both volcanic events induced local base-level modifications and changes in the accommodation/supply ratio, compelling the fluvial network to reorganize. We propose a conceptual model delineating the primary hydromorphic responses to effusive and explosive eruptions, which may provide insights for intra-arc basins within the Andes and comparable systems worldwide.