Preliminary Evaluation of Sinter Deposits at the Río Calientes, Kovire, and Casiri-Kallapuma Geothermal Systems in Southern Perú

The high-altitude Andes mountain chain in southern Perú is characterized by multiple high-temperature geothermal systems, associated with Quaternary arc volcanism. Previous studies have identified this area as having the highest geothermal potential in the country, although no resources have been developed to date except for some local balneology (hot pools for soaking). Structural controls on geothermal system geometry and upflow/outflow locations appear likely, with prominent fault scarps present in many geothermal areas, and alignment of springs sometimes occurring along mapped and inferred fault locations. The main local faults are typically normal with a strike direction NW-SE and N-S. In this study, we conduct preliminary mapping and characterization of sinter deposits at three geothermal systems in the Tarata, Ticaco and Candarave districts in the Tacna region, southern Perú. The systems are located at elevations greater than 4300 m above sea level, and all have boiling springs or geysers present (with a boiling temperature of ~86 °C at this elevation) and are actively depositing sinter today. Paleo-sinter deposits are also present at all three systems, and the modern and paleo-sinter samples collected are dominantly Opal-A silica (indicated by XRD analysis). Rio Calientes (the hot river) is located just east of Yucamane volcano, and is also known as the valley of geysers: along a ~6 km length of the river, there are multiple boiling and geysering alkali-chloride springs and large fossil sinter terraces. The Kovire geothermal system is located to the north of Pisacani volcano, and includes areas of acid-sulfate alteration and mudpots, and boiling springs that discharge alkali-chloride fluids. The Casiri-Kallapuma geothermal system is located north of Casiri Volcano, and also includes areas of intensive acid-sulfate alteration (near Casiri Lagoon and in the Chungara Ravine), and alkali-chloride outflow down-gradient to the north.