11-9 Magmatic Evolution of the Sosneado Volcano (Mendoza, Argentina): Lithofacies Analysis and Eruptive History

Session: Using Volcanic Deposits to Help Us Understand Volcanic and Magmatic Processes

Presenting Author:

Martina Rizzo

Authors:

Rizzo, Martina¹, Iannelli, Sofía Belén², Litvak, Vanesa Dafne³

(1) National Scientific and Technical Research Council (CONICET), Instituto de Estudios Andinos "Don Pablo Groeber" (UBA-CONICET), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina; University of Buenos Aires, Department of Geological Sciences, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina, (2) National Scientific and Technical Research Council (CONICET), Instituto de Estudios Andinos "Don Pablo Groeber" (UBA-CONICET), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina; University of Buenos Aires, Department of Geological Sciences, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina, (3) National Scientific and Technical Research Council (CONICET), Instituto de Estudios Andinos "Don Pablo Groeber" (UBA-CONICET), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina; University of Buenos Aires, Department of Geological Sciences, Ciudad Autónoma de Buenos Aires, Buenos AIres, Argentina,

Abstract:

Sosneado Volcano is a Plio-Pleistocene stratovolcano located near the headwaters of the Atuel River, east of the Main Cordillera of the Southern Central Andes (Argentina) (34°45'30"S - 69°58'14"W). It is part of a cluster of eruptive centers located in a rear-arc position, between the current volcanic arc and the Payenia back-.arc. This work presents the results of the geological survey of the northwestern slope of the Sosneado Volcano, with the primary objective of defining the main eruptive styles. The volcanism of Sosneado Volcano begins with a predominantly explosive episode, represented by diffused-stratified tuffs (dsT) and massive lapilli-tuffs (mLT), which are interpreted as pyroclastic flows or pyroclastic density currents. It continues with a minor effusive event, associated with subaerial lava flows and represented by the foliated coherent andesite (fcA) facies. In a second stage, the volcanism of Volcano Sosneado comprises a distinctly effusive event represented by subaerial lava flows. Compositionally, they correspond to the coherent andesite (cA) and coherent feno-andesite (cFA) lithofacies. Finally, this volcanism ends with a predominantly explosive event associated with coarser facies, comprising massive lithic breccias (mlBr) and crystal-rich lapilli (crL). The first level of lithic breccias was interpreted as a block and ash deposit, which would be related to the collapse of a dome represented by the lateral association of the lithic breccia facies with a coherent andesite (cA) lava level. On the other hand, the crystal-rich lapilli (crL) level is interpreted as a pyroclastic flow or density current. The development of Sosneado magmatism took place during the Plio-Pleistocene period. Particularly, in the early Pliocene, the steepening and destabilization of the Nazca Plate caused the westward retreatment of arc-related magmatism, until it stabilized in its current position. In this context, contemporaneously, between the active volcanic arc and the back-arc, a magmatic belt developed in an anomalous rear-arc position in which the Sosneado volcano is located.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4712

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