Estudio petrográfico de las rocas provenientes del volcán Puñalica : estudio petrográfico de las rocas provenientes del volcán Puñalica.

Abstract

This work presents a petrological and geochemical analysis of samples from the Puñalica volcano. The study was based on the description of mineral and textural families present in 20 different rocks, as well as their geochemical analysis. The detailed description of thin sections allowed the definition of three textural families, differentiated by the content and size of phenocrysts and vesicles, as well as several mineral families based on the characteristics present in crystals and cumulates. A model of magma evolution for the Puñalica volcano is presented, which is related to different periods of eruptive activity. The first phase was marked by the presence of residual magma within a medium-depth chamber. In the second phase, a more basic and hotter magma from a deeper chamber partially mixed with the residual magma. This mixture produced a new magma with a different composition. Regarding the eruptive stages, it was determined that a portion of the more basic magma was able to reach the surface through a fissure eruption, generating long lava flows that reached the farthest distances from the vent, forming samples of textural family 1. After the magma mixing, it is interpreted that the chamber's temperature decreased, leading to phases of strombolian and vulcanian activity, generating textural families 2 and 3. A final eruptive phase produced lava flows that traveled shorter distances from the vent and whose rock has a textural family 1.