| Title | Surface hydrothermal alteration and evolution at the Azufre volcano, Central Volcanic Zone, Chile |
|---|---|
| Authors | B. REIJNST, O. GONZÁLEZ-MAUREL, J. GERDING, S. MAZA, B. GODOY, D. CÁCERES-BAEZ |
| Year | 2025 |
| Conference | LATAM Geothermal Congress |
| Keywords | Azufre volcano, Central Andes, hydrothermal alteration |
| Abstract | The Azufre volcano (21°47'S; 68°15'W) is a Pleistocene stratovolcano that forms part of the Azufre-Inacaliri Volcanic Chain located in the Central Volcanic Zone of the Andes. It consists of two coalescent structural units (Northern and Southern edifices) formed during four magmatic stages (I–IV) between ~1300 and 120 ka and exhibits extensive hydrothermal alteration at the surface. Several studies have described its volcanic and petrogenetic history [1, 2, 3]. Such studies, however, briefly described some of the hydrothermal alteration and related mineralogy. The present study aims to describe in detail the mineralogical characteristics of the surface alteration using remote spectral analysis together with X-ray diffraction analysis of altered rock samples from the Azufre volcano. The alteration minerals identified include silica polymorphs (cristobalite, tridymite, opal-A, opal-CT and quartz), sulphates (jarosite, gypsum and alunite), K-clay minerals (kaolinite), and native sulfur. Th |