Ordovician submarine to subaerial volcanism along the western Gondwana margin: records of the Famatinian belt evolution, sierras pampeanas, Argentina

Abstract

The study of volcanic deposits along active margins provides an excellent tool to understand geodynamic processes linked to tectonic evolution. Such processes can be understood from compositional, lithofacial and textural studies of the volcanic deposits (Allen et al. 2007). The Suri- Las Planchadas Volcanic- Sedimentary Complex (SPVSC), that build up the Las Planchadas and Narváez hills (northwestern portion of the Sierras Pampeanas, Argentina) forming part of the proto-Andean margin, represents a well exposed example of the Famatinian arc with a complete record of the volcanic activity during the Early to Middle Ordovician. Lithofacies analysis based on features as composition, textures and structures of these ancient successions give insights on the emplacement mechanisms and eruption styles of volcanism during the evolution of the Famatinian arc. Likewise, this work attempts to contribute elements of analysis for the understanding of other ancient volcanic successions. Previous descriptions and interpretations of the SPVSC published by the authors, have focused on stratigraphic aspects and local petrographic and geochemical studies as tools to explain specifi c source processes (Cisterna and Coira 2014, 2017 and Cisterna et al. 2017, among others). This work analyses the characteristics and distribution of volcanic facies, focusing on styles of volcanic activity and sedimentation. Detailed facies analysis is based on mapping and profi les across the Las Planchadas and Narváez hills, and takes into account new data, previous works and the regional structures aff ecting the area.