Radiocarbon Dating of Silica Sinter and Postglacial Hydrothermal Activity in the El Tatio Geyser Field

Abstract

The El Tatio geothermal field in the Chilean Altiplano contains hydrothermal silica sinter deposits overlaying glacial and volcanic units, providing an opportunity to constrain the timing of deglaciation and volcanic activity in an area with sparse absolute chronologies. We obtained 51 new radiocarbon ages and δ13C values on the organic material trapped in these sinter deposits. Based on the δ13C values, we exclude 29 samples for possible contamination with bacterial mats that incorporate old carbon. We infer that hydrothermal activity initiated ~27 ka ago and has been nearly continuous ever since. The ages of the oldest sinter deposits coincide with ages of moraines that stabilized after the most recent deglaciation. Whereas late Pleistocene sinters are broadly distributed in the field, Holocene deposits are found around active hydrothermal features. Although recent volcanism is absent in the vicinity of El Tatio, persistent hydrothermal discharge implies a long‐lived magmatic heat source.

Lipid Profiles From Fresh Biofilms Along a Temperature Gradient on a Hydrothermal Stream at El Tatio (Chilean Andes), as a Proxy for the Interpretation of Past and Present Biomarkers Beyond Earth

“…In this study, the extensive set of diverse and relatively complex lipids with variable but generally depleted carbon isotopic signatures of heterogeneous distribution within homologous lipid series, together, attest to a biogenic fingerprint. In the same geyser field of El Tatio, sinter deposits are reported to display bulk δ 13 C values comparable to those measured here for the fresh biofilms, more similar to CE3 and CE4 in proximal slopes (40-75 • C; from -9.9 to -16.9 ), or to CE6 in near vent deposits (> 75 • C; from -15.9 to -25.1 ) (Muñoz-Saez et al, 2020). More specifically, individual δ 13 C values of apolar (from -22 to -28 ), acid (from -20 to -37 ), and polar (from -25 to -30 ) lipids contained in sinter deposits from hydrothermally active and inactive geyser mounds in El Tatio (Sánchez-García et al, 2019) were also in the (lower) range of those measured here in the eight fresh biofilms.…”

Morphogenesis of digitate structures in hot spring silica sinters of the El Tatio geothermal field, Chile

“…The geothermal waters at El Tatio have a low boiling point ~86°C (Hurwitz & Manga, 2017 ) and are characterized by high levels of sodium and chloride ions ([Na + ] up to 4650 ppm, [Cl − ] up to 8100 ppm) and dissolved silica ([SiO 2 ] up to 319 ppm) (Munoz‐Saez et al, 2018 ), although in many springs, silica appears to be undersaturated (Cortecci et al, 2005 ; Fernandez‐Turiel et al, 2005 ; Munoz‐Saez et al, 2018 ; Tassi et al, 2005 ). Due to high elevation and the specific dry, desert environment, the rate of water evaporation is the highest among geothermal springs around the world (Munoz‐Saez et al, 2020 ; Slagter et al, 2019 ).…”

“…Here we present a detailed study of digitate silica sinters —finger‐like growth structures (Lowe & Braunstein, 2003 ; Lynne, 2012 ; Ruff & Farmer, 2016 )—that form ubiquitously in distal, low‐temperature regimes of the El Tatio geothermal field, Chile. This high‐altitude geothermal field is extremely arid, windy and has one of the highest silica‐precipitation rates found in the world (Munoz‐Saez et al, 2020 ; Slagter et al, 2019 ). We describe the spatial distribution and orientation of these digitate sinters, their texture and composition in cross‐section, and the distribution of microbial communities in both their subaerial and submerged components.…”

Environmental and Hydrogeochemical Controls of Spicular Geyserite in Opaline Hot Spring Deposits

“…One‐week of data in the shoulder seasons might not fully reflect the weather complexity of an entire year, including extreme cold temperatures in winter and occasional storms. In the case of the precipitation rates obtained from dating fossil sinter deposits, these should only be regarded as average rates which are affected by uncertainties in the deposit stratigraphy, potential precipitation hiatuses and/or silica infill (Churchill et al., 2020; Munoz‐Saez et al., 2020). Finally, note that trace elements such as Al, Fe, Mg, or the presence of salts can decrease the solubility of silica, promoting precipitation as well (Goto, 1956; Ichikuni, 1970; Iler, 1955; Marshal, 1980; Rimstidt & Cole, 1983), which could also conceal the apparent discrepancy.…”