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Geology topics

J. Michael Thompson

Publications and source records attributed to J. Michael Thompson.

9 recordsLinked to original sources
USGS2009

Seasonal variations of Zn/Cu ratios in acid mine water from Iron Mountain, California

Time-series data on Zn/Cu weight ratios from portal effluent compositions [(Zn/Cu) water ] at Iron Mountain, California, show seasonal variations that can be related to the precipitation and dissolution of melanterite [(Fe II ,Zn,Cu)SO 4 ·7H 2 O]. Mine water and actively forming melanterite were collected from underground mine workings and chemically analyzed. The temperature-dependent solubility of Zn-Cu-bearing melanterite solid solutions was investigated by heating-cooling experiments using the mine water. Rapid kinetics of melanterite dissolution and precipitation facilitated reversed solubility experiments at 25°C. Non-reversed solubility data were obtained in the laboratory at 4° and 35°C and at ambient underground mine conditions (38° and 42°C). Copper is partitioned preferentially to zinc into melanterite solid solutions at all temperatures investigated. During the annual dry season, values of (Zn/Cu) water in the Richmond portal effluent increase to values between 8 to 13, consistent with formation of melanterite during this period. During the annual wet season, the onset of high discharge from the mine portals is characterized by a significant decrease in (Zn/Cu) water to values as low as 2. This phenomenon may be caused by dissolution of melanterite with values of (Zn/Cu) solid ranging from 1.5 to 3.5.

California↗
USGS1994

Convective heat discharge of Wood River group of springs in the vicinity of Crater Lake, Oregon

Data sets for spring and stream chemistry are combined to estimate convective heat discharge and discharge anomalous amounts of sodium and chloride for the Wood River group of springs south of Crater Lake. The best estimate of heat discharge is 87 MW t based on chloride inventory; this value is 3-5 times the heat input to Crater Lake itself. Anomalous discharges of sodium and chloride are also larger that into Crater Lake. Difference between the chemical and thermal characteristics of the discharge into Crater Lake and those from the Wood River group of springs suggest that the heat sources for the two systems may be different, although both ultimately related to the volcanic system.

Oregon↗
USGS1993

Composition of steam in the system NaCl-KCl-H 2 O-quartz at 600°C

In the system NaCl-KCl-H2O, with and without ??-quartz present, steam was equilibrated in a large-volume reaction vessel with brine and/or precipitated salt at 600??C and pressures ranging from about 100 to 0.4 MPa. Episodically, steam was extracted for chemical analysis, accompanied by a decrease in pressure within the reaction vessel. In the absence of precipitated salt, within the analytical uncertainty stoichiometric quantities of Cl and total alkali, metals (Na + K) dissolve in steam coexisting with chloriderich brine. In contrast, in the presence of precipitated salt (in our experiments halite with some KCl in solid solution), significant excess chloride as associated hydrogen chloride (HCl0??) dissolves in steam. The HCl0 is generated by the reaction of steam with solid NaCl(s), producing solid NaOH(s) that diffuses into halite, forming a solid solution. In our quasistatic experiments, compared to dynamic flow-through experiments of others, higher initial ratios of H2O/NaCl have apparently resulted in higher model fractions of NaOH(s) in solid solution in halite. This, in turn, resulted in incrementally higher concentrations of associated NaOHo dissolved in steam. Addition of quartz to the system NaCl + KC1 + H2O resulted in an order of magnitude increase in the concentration of HCl0 dissolved in steam, apparently as a consequence of the formation of sodium disilicate by reaction of silica with NaOH(s). The measured dissolved silica in steam saturated with alkali halides at 600??C in the pressure range 7-70 MPa agrees nicely with calculated values of the solubility of ??-quartz obtained using the equation of Fournier and Potter (1982), corrected for dissolved salt by the method of fournier (1983). Na K ratios in steam at 600??C tend to be slightly greater than in coexisting brine. When precipitated halite is present, larger mole fractions of NaOH(s) in solid solution in that halite apparently result in even larger Na K ratios in coexisting steam. Precipitation of more halite as a consequence of repeated depressurization episodes results in decreased Na K ratios in both the brine and coexisting steam phases, indicating that the lower pressures begin to favor K over Na in the vapor. When steam is in contact with precipitated salts in the absence of brine, the Na K ratio in the steam is less than that of the bulk composition of the salt-H2O system. ?? 1993.

Geochimica et Cosmochimica Acta↗
USGS1985

WATER CHEMISTRY AND MINERALOGY OF MORGAN AND GROWLER HOT SPRINGS, LASSEN KGRA, CALIFORNIA.

Because these springs contain substantial amounts of dissolved chloride, halite and sylvite are found above the water level as evaporitic deposits, along with gypsum. One spring is depositing pyrite that contains significant amounts of arsenic, antimony, and thallium. A yellow compound, composed of arsenic and sulfur, is being deposited in another spring. Arsenic and antimony concentrations are high in the spring waters; the dissolved thallium concentration is not known. The dissolved arsenic appears to be a conservative species and follows chloride. Antimony appears to be independent of dissolved arsenic and to be linearly related to chloride and measured orifice temperature at Morgan Hot Springs.

Conference Paper↗
USGS1984

KONOCTI BAY FAULT ZONE, LAKE COUNTY, CALIFORNIA: A REEVALUATION.

The Konocti Bay Fault Zone (KBFZ), initially regarded by some as a promising liquid-dominated hydrothermal system, has been a disappointment as a geothermal prospect. Five exploratory wells have been drilled in the vicinity of the KBFZ, but none of them are producing thermal fluids; in fact, three have been abandoned. This may be because hydrothermal fluid discharges along the KBFZ are low. The Na-K-Ca and Na-Li geothermometers indicate that the waters discharging around Howard and Seigler Springs may have equilibrated at temperatures above 200 degree C. If boiling has occurred or is occurring, a chloride-enthalpy diagram may be appropriate. Such a diagram for the KBFZ shows that a water in excess of 250 degree C existed or may exist in the area. However, because currently measured temperatures rarely exceed 50 degree C and magnesium concentration in the water is high, very little deep high temperature water may be present. Refs.

Conference Paper↗