Constraints on the nature and evolution of the volcanic fields of the Andahua Group, Central Volcanic Zone, southern Peru

Abstract

The Andahua Group is a distinct cluster of typically monogenetic volcanoes located in the northernmost part of the Central Volcanic Zone in the Andes, characterized by small-volume lava domes and scoria cones. Seven volcanic clusters have been distinguished. Using satellite imagery, geological mapping, and fieldwork, we found a total of 103 lava domes, 43 scoria cones, and 3 small composite volcanoes. Most of the lava domes are monogenetic but 9 were formed by multiple eruptions. Petrogenetic models have been developed for the magma evolution of the Andahua Group. They show local crustal influence on the magmas generated, and possible controls on the magma pathway to the surface, and potential segregation. Local compositional variation of the crustal rocks is inferred to have a strong influence on the magma that ascends through the thick continental crust. Assimilation and contamination by deeply seated granitoids of the Arequipa and Paracas massifs are also inferred to play a role in the final magmatic products. Future activity with gas emissions from the Andahua Group volcanoes may cause hazardous conditions for tourists.