Neogene ignimbrites and volcanic edifices in southern Peru: stratigraphy, time-volume-composition relationships, and recent tephra chronology

Abstract

In the northem Central Andes of southern Peru, four volcanic ares, termed Tacaza, Lower and Upper Barroso, and Frontal are, have been active over the past 30 Ma (Fig. 1). They produced ñve volamic units between Moquegua and Nazca (14°30-17'15'° S and 70-74°W). The “Neogene ignimbrites” unit (< 25 Ma) comprises five generations of widespread igoimbrite sheets (>5OO km2 and >20 km3), representing a major crustal melting event, triggered by thickening and advective beat imput from the mantle wedge. Also, four generations of volcanic edifices (i.e sbields, composite eones, and dome clusters) and monogenetic fields are intercalated with, and mostly overlie, the igoimbrites based on ages, stratigraphy, and mapping.