Volcanic stratigraphy of the Quaternary La Garrotxa Volcanic Field (north-east Iberian Peninsula)

Abstract

The monogenetic Quaternary La Garrotxa Volcanic Field forms part of the Catalan Volcanic Zone (north-east Iberian Peninsula), one of the alkaline volcanic provinces of the European rift system. It harbours more than 50 basaltic monogenetic cones that range in age from the Middle Pleistocene to the Early Holocene and include cinder and scoria cones, lava flows, tuff rings and maars. This study is the result of extensive fieldwork, including the study of ephemeral outcrops and the stratigraphic logging of new water wells and geotechnical drill holes, also taking into account existing information gathered by recent geophysical studies that have applied shallow geophysical methods to establish the substrate geology of this volcanic field. We have obtained a comprehensive volcanic stratigraphy of the area that identifies the products of each single eruption, their relative stratigraphy and their surface area. This volcanic stratigraphy constitutes an essential tool for understanding the evolution of this volcanic field and for establishing a correct volcanic hazard assessment for the area, but it also provides a precise reference for the Quaternary tephrochronology of the lake sediments in neighbouring areas. © 2014 John Wiley & Sons, Ltd.