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Nancy L. Nehring

Publications and source records attributed to Nancy L. Nehring.

4 recordsLinked to original sources
USGS1983

ORIGIN OF THERMAL FLUIDS AT LASSEN VOLCANIC NATIONAL PARK: EVIDENCE FROM NOBLE AND REACTIVE GAS ABUNDANCES.

Thermal fluid discharges at Lassen are dominated by high-altitude fumaroles and acid-sulfate hot springs in the Park, and lower altitude, neutral, high-chloride hot springs in Mill Valley 7-10 km to the south. The interrelations of these fluids have been studied by noble and reactive gas analyses. Atmospheric noble gas (ANG) contents of superheated fumaroles are similar to those of air-saturated recharge water (ASW) at 5 degree C and 2500-m elevation. Low-elevation, high-chloride, hot-spring waters are highly depleted in ANG, relative to the ASW. The surface temperatures and gas chemistry of the fumaroles and hot springs suggest that steam originating from partial to near-complete vaporization of liquid from a boiling, high-chloride, hot water aquifer is decompressed adiabatically, and more or less mixed with shallow groundwater to form superheated and drowned fumaroles within the Park. Refs.

Conference Paper↗
USGS1983

STABLE ISOTOPE GEOCHEMISTRY OF THERMAL FLUIDS FROM LASSEN VOLCANIC NATIONAL PARK, CALIFORNIA.

In the Lassen vapor-dominated geothermal system, surface manifestations of thermal fluids at high elevations (1800-2500 m) include superheated and drowned fumaroles, steam-heated acid-sulfate hot springs, and low-chloride bicarbonate springs. Neutral high-chloride hot water discharges at lower elevations. Deuterium and oxygen-18 data establish genetic connections between these fluids and with local meteoric waters. Steam from the highest temperature fumarole at Bumpass Hell and water from the highest chloride hot spring have isotopic compositions corresponding to vapor-liquid equilibrium at 235 degree C. Carbon and sulfur isotope data suggest that the CO//2 and H//2S in the system did not entirely originate from magmatic sources, but probably include contributions from thermal metamorphism of marine sedimentary rocks. Observations suggest that carbon and sulfur isotope variations are useful indicators of gas reactions and flow paths in geothermal systems. Refs.

Conference Paper↗
USGS1979

Sulfate geothermometry of thermal waters in the western United States

Sulfate geothermometry recently gained acceptance as a geothermal exploration tool when it was adopted as one of the geothermometers in the Assessment of Geothermal Resources of the United States-1978 (Muffler 1979). Over 120 samples, 75 of which are from Known Geothermal Resource Areas, were used in the assessment. Data required for calculation of the sulfate geothermometer temperatures, along with Na-K-Ca, quartz, and chalcedony geothermometer temperatures for comparison, are listed in table 1. For greater accuracy data from new or better samples have occasionally supplemented or replaced data used in the 1978 assessment. Samples from Yellowstone National Park has been omitted because they were discussed by McKenzie and Truesdell (1974).

Open-File Report↗