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J. M. Thompson

Publications and source records attributed to J. M. Thompson.

At least 19 recordsLinked to original sources
USGS2003

Slightly thermal springs and non-thermal springs at Mount Shasta, California: Chemistry and recharge elevations

Temperature measurements, isotopic contents, and dissolved constituents are presented for springs at Mount Shasta to understand slightly thermal springs in the Shasta Valley based on the characteristics of non-thermal springs. Non-thermal springs on Mount Shasta are generally cooler than mean annual air temperatures for their elevation. The specific conductance of non-thermal springs increases linearly with discharge temperature. Springs at higher and intermediate elevations on Mount Shasta have fairly limited circulation paths, whereas low-elevation springs have longer paths because of their higher-elevation recharge. Springs in the Shasta Valley are warmer than air temperatures for their elevation and contain significant amounts of chloride and sulfate, constituents often associated with volcanic hydrothermal systems. Data for the Shasta Valley springs generally define mixing trends for dissolved constituents and temperature. The isotopic composition of the Shasta Valley springs indicates that water fell as precipitation at a higher elevation than any of the non-thermal springs. It is possible that the Shasta Valley springs include a component of the outflow from a proposed 210??C hydrothermal system that boils to supply steam for the summit acid-sulfate spring. In order to categorize springs such as those in the Shasta Valley, we introduce the term slightly thermal springs for springs that do not meet the numerical criterion of 10??C above air temperature for thermal springs but have temperatures greater than non-thermal springs in the area and usually also have dissolved constituents normally found in thermal waters. ?? 2002 Elsevier Science B.V. All rights reserved.

Journal of Volcanology and Geothermal Research↗
USGS1996

Volatile emissions from the crater and flank of Oldoinyo Lengai volcano, Tanzania

As a comparison to airborne infrared (IR) flux measurements, ground-based sampling of fumarole and soil gases was used to characterize the quiescent degassing of CO 2 from Oldoinyo Lengai volcano. Aerial and ground-based measurements are in good agreement: ∼75% of the aerially measured CO 2 flux at Lengai (0.05–0.06 × 10 12 mol yr −1 or 6000–7200 tonnes CO 2 d −1 ) can be attributed to seven large crater vents. In contrast to Etna and Vulcano Island, where 15–50% of the total CO 2 flux emanates diffusely through the volcanic flanks, diffuse emissions were measured only within 500 m of the crater rim at Lengai, contributing <2% of the total flux. The lack of extensive flank emissions may reflect the dimensions of the magma chamber and/or the lack of a shallow fluid flow system. Thermodynamic restoration of fumarole analyses shows that gases are the most CO 2 -rich and H 2 O-poor reported for any volcano, containing 64–74% CO 2 , 24–34% H 2 O, 0.88–1.0% H 2 , 0.1–0.4% CO and <0.1% H 2 S, HCl, HF, and CH 4 . Volatile emissions of S, Cl, and F at Oldoiyno Lengai are estimated as 4.5, 1.5, and 1.0 × 10 7 mol yr −1 , respectively. Accuracy of the airborne technique was also assessed by measuring the C emission rate from a coal-burning power plant. CO 2 fluxes were measured within ±10% near the plant; however, poor resolution at increased distances caused an underestimation of the flux by a factor of 2. The relatively large CO 2 fluxes measured for alkaline volcanoes such as Oldoinyo Lengai or Etna may indicate that midplate volcanoes represent a large, yet relatively unknown, natural source of CO 2 .

Journal of Geophysical Research B: Solid Earth↗
USGS1993

The Geysers-Clear Lake area, California: Thermal waters, mineralization, volcanism, and geothermal potential

Manifestations of a major thermal anomaly in the Geysers-Clear Lake area of northern California include the late Pliocene to Holocene Clear Lake Volcanics, The Geysers geothermal field, abundant thermal springs, and epithermal mercury and gold mineralization. The epithermal mineralization and thermal springs typically occur along high-angle faults within the broad San Andreas transform fault system that forms the western boundary of the North American plate in this area. The young volcanic rocks overlie Mesozoic marine rocks of the Great Valley sequence which have been thrust above the coeval Franciscan Complex and penecontemporaneously dropped back down along low-angle detachment faults.Many of the waters of the region are nonmeteoric as defined by their isotopic signature. One type of isotopically shifted water emerges from or near Great Valley sequence rocks and is the most chloride rich. It is interpreted to be evolved connate in origin. A second type, evolved meteoric water, has moderate chloride contents, high boron contents, and high B/Cl ratios and is found locally in Franciscan rocks, notably at the Sulphur Bank mercury mine, where it probably results from near-closed-system, repeated boiling of meteoric water in host rocks that also contribute organic components to the water. At the Sulphur Bank mine fracturing of otherwise impermeable Franciscan rocks by faulting has created a localized zone of permeability in which thermal water boils repeatedly with limited venting to the surface. Boron-rich fluids were apparently present at depth in The Geysers geothermal field when intrusion of silicic magma occurred, because the concealed intrusion of felsite is surrounded by a halo of tourmaline-bearing hornfels. The volume of this poorly dated early to middle Quaternary intrusive body probably exceeds the 100 km 3 of erupted Clear Lake Volcanics. Similar intrusions may have occurred in the eastern part of the area at Wilbur Springs and the McLaughlin mine, where gold deposition and evidence of hydrothermal phenomena suggest more magmatic activity than is indicated by the small exposed bodies of early Quaternary basaltic lava. The Clear Lake Volcanics are the present locus of volcanism in the northern Coast Ranges and progressively older volcanic centers occur to the south. Geophysical data suggest that a large silicic magma body may be centered north of The Geysers steam field, providing the heat for the geothermal field.Geothermal power production has peaked at The Geysers and pressure declines indicate significant depletion of the fluid resource. The vapor-dominated field evolved from a preexisting hydrothermal system within fractured, otherwise impermeable Franciscan metamorphic rocks. A deep water table of saline fluid has been postulated to be present under the steam field, but no chloride-rich water has been found at drillable depth. We propose that recently discovered, isotopically shifted steam in the northwest Geysers area indicates the presence not of deep connate water but xather of boiled-down, boron-rich Franciscan evolved meteoric water. This water is likely to be present in limited quantities and will not provide a significant hot water resource for geothermal power production at The Geysers field or from the main Clear Lake volcanic field.

Economic Geology↗
USGS1992

Thermal waters along the Konocti Bay fault zone, Lake County, California: a re-evaluation

The Konocti Bay fault zone (KBFZ), initially regarded by some as a promising target for liquid-dominated geothermal systems, has been a disappointment. At least five exploratory wells were drilled in the vicinity of the KBFZ, but none were successful. Although the Na-K-Ca and Na-Li geothermometers indicate that the thermal waters discharging in the vicinity of Howard and Seigler Springs may have equilibrated at temperatures greater than 200??C, the spring temperatures and fluid discharges are low. Most thermal waters along the KBFZ contain >100 mg/l Mg. High concentrations of dissolved magnesium are usually indicative of relatively cool hydrothermal systems. Dissolution of serpentine at shallow depths may contribute dissolved silica and magnesium to rising thermal waters. Most thermal waters are saturated with respect to amorphous silica at the measured spring temperature. Silica geothermometers and mixing models are useless because the dissolved silica concentration is not controlled by the solubility of either quartz or chalcedony. Cation geothermometry indicates the possibility of a high-temperature fluid (> 200??C) only in the vicinity of Howard and Seigler Springs. However, even if the fluid temperature is as high as that indicated by the geothermometers, the permeability may be low. Deuterium and oxygen-18 values of the thermal waters indicate that they recharged locally and became enriched in oxygen-18 by exchange with rock. Diluting meteoric water and the thermal water appear to have the same deuterium value. Lack of tritium in the diluted spring waters suggest that the diluting water is old. ?? 1992.

Journal of Volcanology and Geothermal Research↗
USGS1992

Geochemistry of waters in the Valley of Ten Thousand Smokes region, Alaska

Meteoric waters from cold springs and streams outside of the 1912 eruptive deposits filling the Valley of Ten Thousand Smokes (VTTS) and in the upper parts of the two major rivers draining the 1912 deposits have similar chemical trends. Thermal springs issue in the mid-valley area along a 300-m lateral section of ash-flow tuff, and range in temperature from 21 to 29.8??C in early summer and from 15 to 17??C in mid-summer. Concentrations of major and minor chemical constituents in the thermal waters are nearly identical regardless of temperature. Waters in the downvalley parts of the rivers draining the 1912 deposits are mainly mixtures of cold meteoric waters and thermal waters of which the mid-valley thermal spring waters are representative. The weathering reactions of cold waters with the 1912 deposits appear to have stabilized and add only subordinate amounts of chemical constituents to the rivers relative to those contributed by the thermal waters. Isotopic data indicate that the mid-valley thermal spring waters are meteoric, but data is inconclusive regarding the heat source. The thermal waters could be either from a shallow part of a hydrothermal system beneath the 1912 vent region or from an incompletely cooled, welded tuff lens deep in the 1912 ash-flow sheet of the upper River Lethe area. Bicarbonate-sulfate waters resulting from interaction of near-surface waters and the cooling 1953-1968 southwest Trident plug issue from thermal springs south of Katmai Pass and near Mageik Creek, although the Mageik Creek spring waters are from a well-established, more deeply circulating hydrothermal system. Katmai caldera lake waters are a result of acid gases from vigorous drowned fumaroles dissolving in lake waters composed of snowmelt and precipitation. ?? 1992.

Journal of Volcanology and Geothermal Research↗
USGS1991

Conditions leading to a recent small hydrothermal explosion at Yellowstone National Park

Porkchop Geyser, in Yellowstone National Park, was the site of a small hydrothermal explosion on September 5, 1989. In the early 1960s, this was a quiescent spring with an intermittent seeping discharge. Infrequent geyser eruptions 3-5 m high started in 1971, and in 1985 the geyser began erupting as a perpetual spouter 6-9 m high. Perpetual spouting at the latter height continued until just before the catastrophic hydrothermal event when the geyser column suddenly rose to a height of 20-30 m, followed immediately by the explosive ejection of sinter blocks up to 1.88 m in maximum dimension and formation of an irregular crater 13.9 m long and 11.7 m wide. The ejected blocks show a variety of siliceous deposits indicative of changing environments of deposition with time, and possibly of prior hydrothermal explosive activity at this site. Water samples from Porkchop were collected and analyzed once in the 1920s, again in 1951, ten times between 1960 and mid-1989, and once in January 1990 after the explosion. Chemical geothermometry shows an increase in the temperature of last water-rock equilibration of about 60 to 70 °C from 1962 through 1989. This may have been the result of drawing water progressively from different and hotter regions of a single reservoir or mixing waters from two different reservoirs with a progressively larger proportion of water being drawn from the hotter reservoir from 1962 through 1989. Boiling of ascending fluids coming from hotter subsurface regions resulted in an increase in the proportion of steam to water discharged by the geyser. A constriction at the exit of the geyser tube throttled the flow of water and steam and allowed water in shallow cavities adjacent to the geyser tube to become heated to the boiling point at pressures greater than normal hydrostatic. We hypothesize that a sudden breaking loose of this constriction, likely triggered by a seasonal increase in subsurface boiling throughout Norris Basin, allowed water and steam to be discharged from Porkchop much more rapidly than previously. This resulted in a drop in pressure within the geyser tube, causing water in adjacent connected chambers to become superheated. An ensuing rapid flashing of superheated water to steam within relatively confined spaces resulted in the hydrothermal explosion.

Wyoming↗
USGS1987

Concentrations of arsenic, antimony, and boron in steam and steam condensate at The Geysers, California

Studies at The Geysers Geothermal Field, California indicate that under some circumstances elements that are transported in the vapor phase can become enriched in the liquid phase. Waters from two condensate traps (steam traps) on steam lines at The Geysers are enriched with arsenic, antimony, and boron compared to the concentrations of these elements in coexisting steam. Concentrations of boron in condensate-trap waters were as high as 160 mg/L, arsenic as high as 35 mg/L, and antimony as high as 200 ??g/L. Enrichment of arsenic, antimony, and boron is at least partially controlled by the partitioning of these elements into the liquid phase, according to their vapor-liquid distribution coefficients, after they are transported in steam. Several of the elements that are most soluble in steam, including arsenic and antimony, are part of the trace-element suite that characterizes precious-metal epithermal ore deposits. ?? 1987.

Journal of Volcanology and Geothermal Research↗
USGS1987

The hydrothermal system of the Calabozos caldera, central Chilean Andes

Active thermal springs associated with the late Pleistocene Calabozos caldera complex occur in two groups: the Colorado group which issues along structures related to caldera collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ???400 ppm Cl at ???250??C by dilution with ???50% of cold meteoric water. The thermal springs in the most deeply eroded part of the caldera were derived from the same parent water by boiling. The hydrothermal system has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos hydrothermal system would be an attractive geothermal prospect were its location not so remote. ?? 1987.

Journal of Volcanology and Geothermal Research↗
USGS1984

Arsenic and antimony in geothermal waters of Yellowstone National Park, Wyoming, USA

A total of 268 thermal spring samples were analyzed for total soluble As using reduced molybdenum-blue; 27 of these samples were also analyzed for total Sb using flame atomic absorption spectrometry. At Yellowstone the Cl As "> ClAs atomic ratio is nearly constant among neutral-alkaline springs with Cl > 100 mg L −1 , and within restricted geographic areas, indicating no differential effects of adiabatic vs . conductive cooling on arsenic. The Cl As "> ClAs ratio increases with silica and decreases with decreasing Cl &#x3A3;CO 3 "> ClΣCO3 ; the latter relationship is best exemplified for springs along the extensively sampled SE-NW trend within the Lone Star-Upper-Midway Basin region. The relationship between Cl As "> ClAs and Cl &#x3A3;CO 3 "> ClΣCO3 at Yellowstone suggests a possible rock leaching rather than magmatic origin for much of the Park's total As flux. Condensed vapor springs are low in both As and Cl. Very high Cl As "> ClAs ratios ( > 1000) are associated exclusively with highly diluted (Cl < 100 mg L −1 ) mixed springs in the Norris and Shoshone Basins and in the Upper White Creek and Firehole Lake areas of Lower Basin. The high ratios are associated with acidity and/or oxygen and iron; they indicate precipitation of As following massive dilution of the Asbearing high-Cl parent water. Yellowstone Sb ranged from 0.009 at Mammoth to 0.166 mg L −1 at Joseph's Coat Spring. Within basins, the Cl Sb "> ClSb ratio increases as the Cl &#x3A3;CO 3 "> ClΣCO3 ratio decreases, in marked contrast to As. Mixed springs also have elevated Cl Sb "> ClSb ratios. White (1967) and Weissberg (1969) previously reported stibnite (Sb 2 S 3 ), but not orpiment (As 2 S 3 ), precipitating in the near surface zone of alkaline geothermal systems.

Geochimica et Cosmochimica Acta↗
USGS1984

A review of progress in understanding the fluid geochemistry of the Cerro Prieto geothermal system

Fluid geochemistry has played a major role in our present understanding of the Cerro Prieto geothermal system. Fluid chemical and isotopic compositions have been used to indicate the origin of water, salts and gases, original subsurface temperature and fluid flow, fluid-production mechanisms, and production-induced aquifer boiling and cold-water entry. The extensive geochemical data and interpretations for Cerro Prieto published from 1964 to 1981 are reviewed and discussed. Fluid geochemistry must continue to play an important role in the further development of the Cerro Prieto field. ?? 1984.

Geothermics↗
USGS1983

Selective concentration of cesium in analcime during hydrothermal alteration, Yellowstone National Park, Wyoming

Chemical and mineralogical studies of fresh and hydrothermally altered rhyolitic material in Upper and Lower Geyser Basins, Yellowstone National Park, show that all the altered rocks are enriched in Cs and that Cs is selectively concentrated in analcime. The Cs content of unaltered rhyolite lava flows, including those from which the altered sediments are derived, ranges from 2.5 to 7.6 ppm. The Cs content of analcime-bearing altered sedimentary rocks is as high as 3000 ppm, and in clinoptilolite-bearing altered sedimentary rocks Cs content is as high as 180 ppm. Altered rhyolite lava flows which were initially vitrophyres, now contain up to 250 ppm Cs, and those which were crystallized prior to hydrothermal alteration contain up to 14 ppm. Mineral concentrates of analcime contain as much as 4700 ppm Cs. The Cs must have been incorporated into the analcime structure during crystallization, rather than by later cation substitution, because analcime does not readily exchange Cs. The Cs Cl "> CsCl of the fluids circulating through the hydrothermal system varies, suggesting that Cs is not always a conservative ion and that Cs is lost from upflowing thermal waters due to water-rock interaction resulting in crystallization of Cs-bearing analcime. The source of Cs for Cs enrichment of the altered rocks is from leaching of rhyolitic rocks underlying the geyser basins, and from the top of the silicic magma chamber that underlies the area. Analcime is an important natural Cs sink, and the high Cs concentrations reported here may prove to be an important indicator of the environment of analcime crystallization.

Geochimica et Cosmochimica Acta↗
USGS1983

Chemical analyses of thermal and nonthermal springs in Lassen Volcanic National Park and vicinity, California

Most thermal waters issuing in Lassen Volcanic National Park (LVNP) are acidic (pH =3.5), low-Cl (concentrations =30 mg/L) hot springs which are characteristic of vapor-dominated hydrothermal systems and, as such, are not useful for liquid chemical geothermometry. Thermal waters at Drakesbad and in Little Hot Springs Valley, hot spring localities characterized by neutral pH and low Cl containing water, may have equilibrated in shallow aquifers so that temperatures estimated by both the Na-K-Ca and Na-Li geothermometers approach the measured spring temperatures of 65? to 95?C. Waters rich in chloride (>2000 mg/L), such as those at Growler Hot Spring and Morgan Hot Springs, situated south of LVNP, are the most appropriate springs for liquid chemical geothermometry and indicate subsurface temperatures between 220? and 230?C. The chemical and thermal characteristics of these springs may result either from boiling at depth and subsequent mixing with meteoric water or from conductive cooling during lateral flow. In either case ~220? to 230?C thermal water probably originates inside LVNP and flows south to Morgan Hot Springs.

Open-File Report↗
USGS1983

SELECTED CHEMICAL ANALYSES AND GEOTHERMOMETRY OF HOT SPRING WATERS FROM THE CALABOZOS CALDERA, CENTRAL CHILE.

Hot springs discharging from the active hydrothermal system associated with the Calabozos caldera, Chile, have measured orifice temperatures as high as 98. 5 degree C and calculated geothermometer temperatures as high as 250 degree C. Three types of spring waters can be identified from the chemical analyses: a Na-Cl type, a Na-HCO//3 type and a Na-mixed anion type. Chloride-enthalpy relations indicate that the hydrothermal reservoir water may attain temperatures near 342 degree C and that most spring waters are mixed with cold meteoric water. Despite the proximity of Mesozoic marine gypsum deposits, the Cl/Br weight ratio of the Calabozos spring waters does not appear to indicate that these waters have a significant 'marine' signature. Refs.

Conference Paper↗