Search USGS⌕ Search

Geology topics

Robert O. Fournier

Publications and source records attributed to Robert O. Fournier.

24 records · Page 2Linked to original sources
USGS1976

Conditions in the deeper parts of the hot spring systems of Yellowstone National Park, Wyoming

Yellowstone thermal areas are scattered over an area of nearly 50 x 60 kilometers (Fig. 1) and contain waters of diverse compositions. This has lead to the implicit assumption that Yellowstone consisted of discrete hydrothermal systems (e.g., Fournier and Truesdell, 1970). It is the purpose of this paper to suggest that these systems may be separate only near the surface and that there may exist at depth a large, relatively homogeneous body of water at 340 to 370°C containing about 1,000 ppm NaCl. This deep thermal water flows upwards losing steam into the near-surface geyser and hot spring systems where it undergoes variable amounts of dilution with cold meteoric water, reaction with rocks, and further steam loss to produce all of the hot spring waters of the Park. The evidence for these conclusions is from the application of chemical and isotopic geothermometers, from relationships between the chloride concentrations and subsurface heat contents of thermal waters, from the chemical and isotopic compositions of the waters, and from geophysical evidence.

Wyoming↗
USGS1976

Geochemical prediction of aquifer temperatures in the geothermal system at Long Valley, California

This paper was written to (1) illustrate a process of evaluating a geothermal energy prospect from a geochemical point of view, and (2) present a geochemical evaluation of the hydrothermal system at Long Valley, California. Temperatures of aquifers feeding thermal springs and wells in Long Valley, California were estimated using silica and Na-K-Ca geothermometers and warm spring mixing models. The results ranged from 160° to 219°C. This information was then used to construct a diagram showing enthalpy-chloride relationships for the various thermal waters in the Long Valley region. The enthalpy-chloride information suggests that a 282°C aquifer with water containing about 375 milligrams chloride per kilogram of water is present somewhere deep in the system. That deep water would be related to 219°C Casa Diablo water by mixing with cold water, and to 201°C Hot Creek water by boiling and steam loss. Oxygen and deuterium isotopic data are consistent with this interpretation. An aquifer at 282°C with 375 mg/kg chloride allows the estimated convective heat flow in Long Valley to be increased from 4.3 x 10 7 to 6.6 x 10 7 cal/sec.

California↗
USGS1967

The porphyry copper deposit exposed in the Liberty open-pit mine near Ely, Nevada; Part 2, The formation of hydrothermal alteration zones

In the southwest part of the Liberty pit a large porphyry body exhibits a zonal alteration pattern related to fissures and pyrite-bearing veins. The outermost zone contains unaltered K-feldspar, kaolinite after plagioclase, and black biotite after hornblende. An intermediate zone contains reconstituted K-feldspar, phlogopitic biotite, and muscovite or muscovite plus K-feldspar replacing only plagioclase. In the innermost zone the only silicates are quartz and muscovite. In some places an alteration band of K-feldspar after plagioclase separates kaolinite and muscovite.The widespread association of kaolinite and K-feldspar in hydrothermal alteration zones suggests that these two minerals were stable together at the time of formation. Experimental data show that, where quartz controls the activity of silica in solution, kaolinite and K-feldspar should react to form muscovite. However, calculations predict that, at 15,000 psi, solutions with silica activities compatible with amorphous or gelatinous silica could stabilize K-feldspar and kaolinite relative to muscovite at temperatures below about 250 degrees C. The rapid decomposition either of plagioclase feldspar or montmorillonite is considered a prime cause for the attainment of such high activities of silica in pore solutions of rock. The supersaturation of pore solutions with silica is a transient condition; quartz precipitates where kaolinite and K-feldspar react to give muscovite. Thus, the zonally distributed alteration at Ely is considered to have taken place after the rock had cooled to below 250 degrees C. In contrast, the diffusely distributed muscovite and montmorillonite found in another portion of the pit probably commenced at 600 degrees to 700 degrees C with only minor formation of alteration products below 250 degrees C.

Nevada↗