Geology topics

Carolina Munoz-Saez

Publications and source records attributed to Carolina Munoz-Saez.

5 recordsLinked to original sources

USGS2025

Applying U-Th disequilbrium for dating siliceous sinters

Continental hydrothermal systems are critical avenues for the crustal transport of heat and mass captured for geothermal energy and mineral exploration. Thus, understanding their temporal evolution and longevity is important for resource characterization. Deposits of microlaminated siliceous sinter, common surface expressions of high temperature reservoirs (> 170 °C), have the potential to trace hydrothermal histories. Geothermal reservoirs are often located within uranium-bearing silicic volcanic rock where subsurface fluid-rock interactions extract U into hydrothermal fluids. U incorporated in the surface sinter deposit has the potential to provide a U— Th disequilibrium dating option. We focus on samples from El Tatio geyser field in the Altiplano of northern Chile, the largest geothermal system in the Andes. Our resulting 230 Th/U ages, along with the water and deposit elemental compositions, suggest concentrations of U and Th vary predictably along the sinter apron. While distal facies containing the highest U concentrations (> 50 μg/g) are least affected by detrital Th corrections, they can display suspected open-system behavior. In contrast, more medial facies, where bacterial mats and other porous textures are co mmonly concentrated, have only trace amounts of U (< 0.1 μg/g), which leads to unreliable or geologically improbable dates. Proximal facies tend to date most consistently. By comparing existing 14 C ages with 230 Th/U results, 230 Th/U ages tend to be younger than the 14 C ages, supporting the presence of a 14 C-dead carbon influence. New data confirm that the onset of geothermal activity at El Tatio goes back to the late Pleistocene.

Altiplano, El Tatio geyser field↗

USGS2021

The 2018 reawakening and eruption dynamics of Steamboat Geyser, the world’s tallest active geyser

Steamboat Geyser in Yellowstone National Park’s Norris Geyser Basin began a prolific sequence of eruptions in March 2018 after 34 y of sporadic activity. We analyze a wide range of datasets to explore triggering mechanisms for Steamboat’s reactivation and controls on eruption intervals and height. Prior to Steamboat’s renewed activity, Norris Geyser Basin experienced uplift, a slight increase in radiant temperature, and increased regional seismicity, which may indicate that magmatic processes promoted reactivation. However, because the geothermal reservoir temperature did not change, no other dormant geysers became active, and previous periods with greater seismic moment release did not reawaken Steamboat, the reason for reactivation remains ambiguous. Eruption intervals since 2018 (3.16 to 35.45 d) modulate seasonally, with shorter intervals in the summer. Abnormally long intervals coincide with weakening of a shallow seismic source in the geyser basin’s hydrothermal system. We find no relation between interval and erupted volume, implying unsteady heat and mass discharge. Finally, using data from geysers worldwide, we find a correlation between eruption height and inferred depth to the shallow reservoir supplying water to eruptions. Steamboat is taller because water is stored deeper there than at other geysers, and, hence, more energy is available to power the eruptions.

Wyoming↗

USGS2021

Why study geysers?

Scientific research for more than two centuries has improved our understanding of Earth’s geysers. This knowledge provides insights into volcanic processes, the origin and environmental limits of life on Earth and potentially Mars, and on geysers on icy outer solar system satellites. Continued scientific research will help us understand and protect these natural wonders that attract millions of tourists annually.

Eos, American Geophysical Union↗

USGS2018

Hydrothermal discharge from the El Tatio basin, Atacama, Chile

El Tatio in northern Chile is one of the best-studied geothermal fields in South America. However, there remain open questions about the mass and energy budgets, water recharge rates and residence time in the subsurface, origin of dissolved solutes, and processes affecting the phase and chemical composition of groundwater and surface water. We measured and sampled surface manifestations of the geothermal system (geysers perpetual spouters, mud pools/volcanoes, and non-eruptive hot springs) and meteoric water. From the isotopic composition we infer that the thermal water has a meteoric origin that is different from the composition of local meteoric water. The absence of detectable tritium in thermal waters indicates that most of the recharge occurred pre-1950. Boiling and steam separation from the deep reservoir appear to be the main subsurface processes affecting the thermal fluids. A large amount of heat is lost to the atmosphere by evaporation from surface water and by steam emitted from erupting geysers. Using the chloride inventory method, we estimate thermal water discharge to be 218 to 234 L/s, and the advective heat flow to be 120 to 170 MW.

El Tatio Basin↗

USGS2015

Dynamics within geyser conduits, and sensitivity to environmental perturbations: insights from a periodic geyser in the El Tatio Geyser Field, Atacama Desert, Chile

Despite more than 200 years of scientific study, the internal dynamics of geyser systems remain poorly characterized. As a consequence, there remain fundamental questions about what processes initiate and terminate eruptions, and where eruptions begin. Over a one-week period in October 2012, we collected down-hole measurements of pressure and temperature in the conduit of an exceptionally regular geyser (132 s/cycle) located in the Chilean desert. We identified four stages in the geyser cycle: (1) recharge of water into the conduit after an eruption, driven by the pressure difference between water in the conduit and in a deeper reservoir; (2) a pre-eruptive stage that follows the recharge and is dominated by addition of steam from below; (3) the eruption, which occurs by rapid boiling of a large mass of water at the top of the water column, and decompression that propagates boiling conditions downward; (4) a relaxation stage during which pressure and temperature decrease until conditions preceding the recharge stage are restored. Eruptions are triggered by the episodic addition of steam coming from depth, suggesting that the dynamics of the eruptions are dominated by geometrical and thermodynamic complexities in the conduit and reservoir. Further evidence favoring the dominance of internal processes in controlling periodicity is also provided by the absence of responses of the geyser to environmental perturbations (air pressure, temperature and probably also Earth tides).

Atacama Desert↗