Michael A. McKibben

University of California, Riverside | UCR · Dept. of Earth & Planetary Sciences, College of Natural and Agricultural Sciences

The existing renewable electrical generation industry at the Salton Sea Geothermal Field has tremendous potential to become a world-class producer of lithium and other critical metals, which can be extracted from geothermal brines. The industry could also generate nontraditional geothermal energy via production of electricity from pumped storage an...

The Salton Sea—a hypersaline, terminal lake in southern California—is in crisis. A combination of mismanagement and competition among federal, state and local agencies has hindered efforts to address declining lake levels and unstable water chemistry. This delay has heightened the public health threat to regional communities as retreating shoreline...

Growth in global metal demand has fostered a new age of unconventional mining on the seafloor. In situ pulverization and extraction of seafloor massive sulfide (SMS) deposits is economically attractive due to minimal overburden and high ore grades. However, important environmental questions remain on the significance of localized acid generation vi...

In the present communcation we report our empirical determinations of chloride complex stoichiometries for Fe, Mn, Zn, Pb, Cu and Cd in the Salton Sea geothermal system brines, comparing them with published experimental data. We find that in the Salton Sea geothermal system brines most base metals are carried as mono- and dichloro complexes. These...

The executive summary.

The three possible reclamation scenarios that have been described in this report for the Salton Sea should be carefully evaluated in the context of how they may impact the ability of the region's geothermal industry to expand its traditional geothermal power resources as well as develop new non-traditional mineral and energy resources in the Salton...

EXECUTIVE SUMMARY The Salton Sea, a hypersaline lake in southern California, USA, is in crisis. A combination of mismanagement and competition between federal, state and local agencies has resulted in stalled efforts to address dropping water levels and unstable lake biogeochemistry. This in turn has led to a growing public health crisis as exposed...

Tungsten, an emerging contaminant, has no EPA standard for its permissible levels in drinking water. At sites in California, Nevada, and Arizona there may be a correlation between elevated levels of tungsten in drinking water and clusters of childhood acute lymphocytic leukemia (ALL). Developing a better understanding of how tungsten is released fr...

A rapid increase in the price of transition metals in recent years has piqued interest in deep sea in situ mining of seafloor massive sulfide (SMS) deposits. There are important unanswered questions about the potential environmental effects of seafloor mining, particularly localized sulfuric acid generation. Currently there is a paucity of data on...

At the moment of its trapping as a primary fluid inclusion, a hydrothermal fluid is typically at or near equilibrium with multiple mineral species at depth and temperature. After trapping, however, the isolated inclusion fluid can re-equilibrate only with its own host mineral species during later uplift and cooling to surface conditions. Because th...

In an effort to help evaluate the significance of common primary As-bearing minerals in releasing As into surface and ground waters, experiments were performed to determine rate laws for the irreversible inorganic aqueous oxidation of arsenopyrite by dissolved O2, Fe³⁺ and in low temperature acidic solutions. Batch reactor run conditions varied fro...

The rate of release of aqueous arsenic from common primary source minerals in rocks and soils has been quantified experimentally, yielding rate equations that can be used in computer modeling of arsenic contamination in surface and subsurface waters. Arsenopyrite, rather than pyrite, has been found to release aqueous arsenic the most rapidly.

The Tono uranium deposit, located in central Japan, is thought to have formed when oxidizing groundwater leached uranium from the underlying Toki Granite and transported it to the overlying host sedimentary formations where it precipitated under reducing conditions. Fission-track dating shows that this uranium mineralization took place ~10 million...

The SHRIMP ion microprobe has been used to make in situ analyses of individual anhydrite and sulfide crystals in the June 1991 eruption products of Mount Pinatubo. In air-fall pumice from the June 12 eruption, anhydrite crystals exhibit a broad, bimodal distribution of 34 S values (46 analyses on 23 crystals; range 3 to 16 per mil; modes of 6.5 per...

Metallic ore deposits constitute the largest geochemical anomalies within the crust. Their study has been critical to understanding the behavior of elements and isotopes in mineral- and rock- forming processes, as well as to deciphering the geochemical differentiation of the Earth through time. The study of ore deposits therefore influences and dra...

In addition to volatiles released from volcanoes, the flux of CO2 to the atmosphere from other sources (e.g., metamorphism and subsurface magmatism) represents an important aspect of the global carbon cycle. We have obtained a direct estimate of the present-day atmospheric CO2 flux from convective hydrothermal systems within subaerial, seismically-...

Mississippi Valley-type ore samples from two mines in the Viburnum trend of southeast Missouri have been examined with the SHRIMP ion microprobe to determine the extent of their microscopic sulfur isotope variations. Approximately 140 SHRIMP δ 34S values were obtained. Microscopic δ 34S variations within and among the intergrown Fe-Cu-Pb-Zn sulfide...

Fe[sup +3](Fe+3) contents have been studied in a suite of over 30 chlorites from a variety of provenances representing a range of F[sub O[sub 2]](FO2) conditions, including: (a) metapelites in western Maine, ranging from lower garnet to upper staurolite grade rocks, coexisting with graphite and Fe+3-poor ilmenite at 375--575 C; (b) extension veins...

Data from 71 geothermal production intervals in 48 wells from the Salton Sea Geothermal System (SSGS) indicate that fluids in that system cluster into two distinct populations in terms of their salinity and their stable isotopic compositions. The distinctive, hot, hypersaline brine (typically >20 wt% total dissolved solids) for which the SSGS is kn...

In situ SHRIMP ion microprobe and conventional techniques were used to determine the sulfur isotopic compositions of accessible sulfur-bearing phases in the Salton Sea geothermal system including: diagenetic sulfate and sulfide minerals in the lacustrine-deltaic host sediments, sulfide minerals in intrusive igneous rocks, sulfate and sulfide minera...

The major phases found in the vicinity of the 1866 m flow zone are K-feldspar, epidote, pyrite, hematite, and chlorite. These are found to exist in primarily four, two-phase assemblages, the dominant being K-feldspar+pyrite, epidote+pyrite, epidote+hematite, and chlorite+pyrite. Complete reaction relations among these isobaric isothermal divariant...

The Salton Sea geothermal system (SSGS) occurs in Plio-Pleistocene deltaic-lacustrine-evaporite sediments deposited in the Salton Trough, an active continental rift zone. Temperatures up to 365°C and hypersaline brines with up to 26 wt.% TDS are encountered at 1–3 km depth in the sediments, which are undergoing active greenschist facies hydrotherma...

Drill cores recovered by the Salton Sea Scientific Drilling Project shed new light on the nature and origin of ore formation in the eastern portion of the Salton Sea geothermal system. Base metal ore mineralization occurs in vertical fractures. Type 1 veins are dominated by carbonate, contain pyrrhotite and other sulfides, are completely sealed, an...

The Salton Sea geothermal system (SSGS) is the site of active hydrothermal metamorphism and metallogenesis in the delta of the Colorado River, which partially fills the Salton Trough rift zone at the head of the Gulf of California. Growth of the delta across the rift has isolated the northern part of the Salton Trough since the Pleistocene, forming...

This book contains 39 papers (by 72 authors) that are based upon invited presentations given at the Symposium on Copper Deposits at the 27th International Geological Congress in Moscow. The symposium was jointly organized and sponsored by the Society of Economic Geologists (SEG), the Society of Geology Applied to Mineral Deposits (SGA), and the Int...

Rate laws have been determined for the aqueous oxidation of pyrite by ferric ion, dissolved oxygen and hydrogen peroxide at 30°C in dilute, acidic chloride solutions. Fresh, smooth pyrite grain surfaces were prepared by cleaning prior to experiments. Initial specific surface areas were measured by the multipoint BET technique. Surface textures befo...

A detailed analysis is made of base metal sulphides in two boreholes, to 2500 m, in the Salton Sea geothermal system. Three types of ore occur: 1) diagenetic mineralization to 760 m; 2) metamorphic mineralization, recrystallized from diagenetic deposits, below 760 m; and 3) vein and pore-filling sulphides, redistributed diagenetic and metamorphic s...

Anion exchange separation of polythionates and thiosulfate by HPLC (high-performance liquid chromatography) followed by differential pulse polarographic determination provides a systematic and sensitive analytical method for mixtures of these aqueous sulfur species. The time necessary for the partial separation of thiosulfate and polythionates is 1...