Artículo de revista
Physico-chemical and environmental controls on siliceous sinter formation at the high-altitude El Tatio geothermal field, Chile
Fecha
2014Registro en:
Journal of Volcanology and Geothermal Research 282 (2014) 60–76
dx.doi.org/10.1016/j.jvolgeores.2014.06.012
Autor
Nicolau del Roure Eylerts, Constanza Beatriz
Reich Morales, Martín
Lynne, Bridget
Institución
Resumen
El Tatio geothermal field is located 4270 m above sea level in the Altiplano, northern Chile. Siliceous sinter deposits
from El Tatio were studied to understand the influence of water chemistry and the extreme climatic conditions
on their textures and mineralogy. The results of this study show that the mineralogy of El Tatio sinters
include of opal-A and accessoryminerals, such as halite, gypsumand cahnite (Ca4B2As2O12∙4H2O),which precipitate
by full evaporation of high arsenic, boron and calciumthermal waters. El Tatio sinters showa high degree of
structural disorder, probably linked to cation incorporation into the silica structure and/or the occurrence of
micro- to nano-scale accessoryminerals. The high content of cations in the thermal waters is strongly tied to relatively
high silica precipitation rates considering silica concentration inwater (147–285mg/l SiO2). Precipitation
rate reach 2.5 kg/m2 per year based on in situ precipitation experiments. The particular environmental conditions
of this high-altitude geothermal area that produce highwater cooling rate and high evaporation rate,may also be
responsible for the fast silica precipitation. Low environmental temperatures create freezing-related sinter textures
(i.e., silica platelets and micro columns/ridges). Silicified microbial filaments are also characteristic of El
Tatio sinters, and they are indicative ofwater temperature and hydrodynamic conditions at themoment of sinter
formation. However, sinter textural interpretation in a high-altitude Andean context must be done carefully as
specific relationships between microbial and hydrodynamic textures are found.