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USGS1978

Revised values for the Gibbs free energy of formation of [Al(OH)4 aq-], diaspore, boehmite and bayerite at 298.15 K and 1 bar, the thermodynamic properties of kaolinite to 800 K and 1 bar, and the heats of solution of several gibbsite samples

Solution calorimetric measurements compared with solubility determinations from the literature for the same samples of gibbsite have provided a direct thermochemical cycle through which the Gibbs free energy of formation of [Al(OH) 4 aq − ] can be determined. The Gibbs free energy of formation of [Al(OH) 4 aq − ] at 298.15 K is −1305 ± 1 kJ/mol. These heat-of-solution results show no significant difference in the thermodynamic properties of gibbsite particles in the range from 50 to 0.05 μm. The Gibbs free energies of formation at 298.15 K and 1 bar pressure of diaspore, boehmite and bayerite are −9210 ± 5.0, −918.4 ± 2.1 and −1153 ± 2 kJ/mol based upon the Gibbs free energy of [A1(OH) 4 aq − ] calculated in this paper and the acceptance of −1582.2 ± 1.3 and −1154.9 ± 1.2 kJ/mol for the Gibbs free energy of formation of corundum and gibbsite, respectively. Values for the Gibbs free energy formation of [Al(OH) 2 aq + ] and [AlO 2 aq − ] were also calculated as −914.2 ± 2.1 and −830.9 ± 2.1 kJ/mol, respectively. The use of [AlC 2 aq − ] as a chemical species is discouraged. A revised Gibbs free energy of formation for [H 4 SiO 4aq 0 ] was recalculated from calorimetric data yielding a value of −1307.5 ± 1.7 kJ/mol which is in good agreement with the results obtained from several solubility studies. Smoothed values for the thermodynamic functions C P 0 , ( H T 0 - H 298 0 ) T "> HT0- H2980)T , ( G T 0 - H 298 0 ) T "> (GT0- H2980)T , S T 0 - S 0 0 , ΔH ƒ,298 0 ">ƒ ΔHƒ,2980 kaolinite are listed at integral temperatures between 298.15 and 800 K. The heat capacity of kaolinite at temperatures between 250 and 800 K may be calculated from the following equation: C P 0 = 1430.26 − 0.78850 T + 3.0340 × 10 −4 T 2 −1.85158 × 10 −4 T 2 1 2 + 8.3341 × 10 6 T −2 "> 12+ 8.3341 × 106T−2 . The thermodynamic properties of most of the geologically important Al-bearing phases have been referenced to the same reference state for Al, namely gibbsite.

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USGS1978

A pollution history of Chesapeake Bay

Present day anthropogenic fluxes of some heavy metals to central Chesapeake Bay appear to be intermediate to those of the southern California coastal region and those of Narragansett Bay. The natural fluxes, however, are in general higher. On the bases of Pb-210 and Pu-239 + 240 geochronologies and of the time changes in interstitial water compositions, there is a mixing of the upper 30 or so centimeters of the sediments in the mid-Chesapeake Bay area through bioturbation by burrowing mollusks and polychaetes. Coal, coke and charcoal levels reach one percent or more by dry weight in the deposits, primarily as a consequence of coal mining operations. ?? 1978.

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USGS1978

Mass transfer and carbon isotope evolution in natural water systems

This paper presents a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered. The results are expressed as equations relating changes in isotopic composition to changes in conventional carbonate chemistry. One implication of the equations is that the isotopic composition of an aqueous phase may approach a limiting value whenever there are simultaneous inputs and outputs of carbonate. In order to unambiguously interpret isotopic data from carbonate precipitates and identify reactants and products in reacting natural waters, it is essential that isotopic changes are determined chiefly by reactant and product stoichiometry, independent of reaction path. We demonstrate that this is so by means of quantitative examples. The evolution equations are applied to: 1. (1) carbon-14 dating of groundwaters; 2. (2) interpretation of the isotopic composition of carbonate precipitates, carbonate cements and diagenetically altered carbonates; and 3. (3) the identification of chemical reaction stoichiometry. These applications are illustrated by examples which show the variation of ??C13 in solutions and in precipitates formed under a variety of conditions involving incongruent dissolution, CO2 degassing, methane production and mineral precipitation. ?? 1978.

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USGS1978

Present day serpentinization in New Caledonia, Oman and Yugoslavia

Geochemical evidence for modern low-temperature serpentinization has been found in three new localities. Apparently the low-temperature reactions are a common mode of formation of the lizardite-chrysotile and brucite assemblage. Possibly the 18O content of serpentine formed at low temperatures is in part inherited from the pyroxene and olivine. ?? 1978.

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USGS1978

Correction of ground-water chemistry and carbon isotopic composition for effects of CO2 outgassing

Direct P co 2 "> P co2 measurements on water samples from several CO 2 -charged warm springs are significantly higher than P co 2 "> P co2 values calculated from field pH and alkalinity (and other constituents). In addition, calcite saturation indices calculated from field pH and solution composition indicated supersaturation in samples which, on the basis of hydrogeologic concepts, should be near saturation or undersaturated. We attribute these discrepancies to uncertainties in field pH, resulting from CO 2 outgassing during pH measurement. Because samples for direct P co 2 "> P co2 measurement can be taken with minimal disturbance to the water chemistry, we have used the measured P co 2 "> P co2 to back calculate an estimate of the field pH and the carbon isotopic composition of the water before outgassing. By reconstructing water chemistry in this way, we find generally consistent grouping of δ 13 C "> δ 13 C , pH, and degree of calcite saturation in samples taken from the same source at different times, an observation which we expect based on our understanding of the hydrogeology and geochemistry of the ground-water systems. This suggests that for very careful geochemical work, particularly on ground-waters much above ambient temperature, P co 2 "> P co2 measurements may provide more information on the system and a better estimate of its state of saturation with respect to carbonate minerals than can field measurements of pH.

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USGS1978

Stereochemistry of amino acids in surface samples of a marine sediment

In two surface samples of marine sediment, the percentages of d -alanine and d -aspartic acid are significantly higher than the other d -amino acids and are similar to the range found in soils. The percentage of d -glutamic acid is also higher than the other amino acids but less than d -alanine and d -aspartic acid. These d -amino acids may come mainly from bacteria.

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USGS1979

Application of a new Raman microprobe spectrometer to nondestructive analysis of sulfate and other ions in individual phases in fluid inclusions in minerals

Rosasco et al . (1975), reported the first successful application of laser-excited Raman spectroscopy for the identification and nondestructive partial analysis of individual solid, liquid, and gaseous phases in selected fluid inclusions. We report here the results of the application of a new instrument, based on back-scattering, that eliminates many of the previous stringent sample limitations and hence greatly expands the range of applicability of Raman spectroscopy to fluid inclusions. Fluid inclusions in many porphyry copper deposits contain 5–10 μm ‘daughter’ crystals thought to be anhydrite but too small for identification by the previous Raman technique. Using the new instrument, we have verified that such daughter crystals in quartz from Bingham, Utah, are anhydrite. They may form by leakage of hydrogen causing internal autooxidation of sulfide ion. Daughter crystals were also examined in apatite (Durango, Mexico) and emerald (Muzo, Colombia). Valid analyses of sulfur species in solution in small fluid inclusions from ore deposits would be valuable, but are generally impossible by conventional methods. We present a calibration procedure for analyses for SO 4 2− in such inclusions from Bingham, Utah (12,000 ± 4000 ppm ) and Creede, Colo. (probably < 500 ppm). A fetid Brazilian quartz, originally thought to contain liquid H 2 S, is shown to contain only HS − in major amounts.

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USGS1979

Low temperature basalt alteration by sea water: an experimental study at 70°C and 150°C

Basaltic glass and diabase were reacted with seawater at 70°C at 1 bar and 150°C at 500 bars to determine fluid composition and alteration mineralogy. All experiments were performed at a water/ rock mass ratio of 10. The changes in seawater chemistry depended on temperature and crystallinity of the basalt. The experiment at 70°C produced a slight but continuous loss of Mg, Na and K and enrichment of Ca and SiO 2 in the seawater while pH decreased slowly. At 150°C, in contrast, Mg and SO 4 were quickly and quantitatively removed while Ca, SiO 2 , Na, K, Fe, Mn and Ba were added to the seawater. pH rose to values between 5.5 and 6.5 after an initial drop to lower values. Basalt glass reacted more extensively at 150°C than diabase. Smectite was the major alteration product (iron-rich saponite) at 150°C for both the glass and diabase experiments. Smectite from the diabase experiment was well crystallized while that from the glass experiment was poorly crystallized. The smectites are similar to smectites found in altered oceanic ophiolitic basalts.

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USGS1979

Origin of dolomite in Miocene Monterey Shale and related formations in the Temblor Range, California

Dolomites in thick sections of Miocene Monterey Shale and related formations in the Temblor Range of California acquired their isotopic compositions as they formed at shallow depth in the original sediment rich in organic matter, and retained the composition against the vicissitudes of burial diagenesis. The oxygen isotopes of dolomites of successive beds record changes in temperature of bottom water while the carbon isotopes of the same samples indicate changes in the kind of microbial activity (sulfate reduction vs carbohydrate fermentation) that prevailed at shallow depths in the sediment. In an auxiliary study, two samples of dolomite from sediments of Cariaco Basin off Venezuela (DSDP site 147) were found to have ??5C13 of -14.1 and -9.8 per ml PDB, although they occur in a heavy-carbon zone containing bicarbonate as heavy as +8.4 per ml. These dolomites probably originated at shallow depth in the light-carbon zone of microbial sulfate reducers and were buried under later sediments down into the heavy-carbon zone of microbial fermenters of carbohydrates without losing their original light-carbon composition. ?? 1979.

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USGS1979

Amino-acid racemizarion in Quaternary shell deposits at Willapa Bay, Washington

Extents of racemization ( d l "> dl ratios) of amino acids in fossil Saxidomus giganteus (Deshayes) and Ostrea lurida Carpenter were measured on shell deposits exposed at 21 sites on the east side of Willapa Bay, Washington. Amino acids from Saxidomus show less variability in d Spl "> dSpl ratios and, therefore, are of greater use in correlation and age estimation than are amino acids from Ostrea . Shells of two different ages, about 120,000 ± 40,000 yr old and about 190,000 ± 40,000 yr old, are present. These ages correspond to Stages 5 and 7 of the marine isotope record defined by Shackleton and Opdyke in 1973 and hence the shell deposits likely formed during two different high stands of sea level. The stratigraphic record at Willapa Bay is consistent with this interpretation.

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USGS1979

Chemical composition of Mars

The composition of Mars has been calculated from the cosmochemical model of Ganapathy and Anders (1974) which assumes that planets and chondrites underwent the same 4 fractionation processes in the solar nebula. Because elements of similar volatility stay together in these processes, only 4 index elements (U, Fe, K and Tl or Ar 36 ) are needed to calculate the abundances of all 83 elements in the planet. The values chosen are U = 28 ppb , K = 62 ppm (based on K U = 2200 "> KU= 2200 from orbital γ-spectrometry and on thermal history calculations by Toksöz and Hsui (1978) Fe = 26.72% (from geophysical data), and Tl = 0.14 ppb (from the Ar 36 and Ar 40 abundances measured by Viking). The mantle of Mars is an iron-rich [ Mg /( Mg + Fe ) = 0.77] garnet wehrlite ( ρ = 3.52−3.54 g / cm 3 ), similar to McGetchin and Smyth's (1978) estimate but containing more Ca and Al. It is nearly identical to the bulk Moon composition of Morgan et al. (1978b). The core makes up 0.19 of the planet and contains 3.5% S—much less than estimated by other models. Volatiles have nearly Moon-like abundances, being depleted relative to the Earth by factors of 0.36 (K-group, T cond = 600–1300 K ) or 0.029 (Tl group, T cond < 600 K ). The water abundance corresponds to a 9 m layer, but could be higher by as much as a factor of 11. Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates mainly with size rather than with radial distance from the Sun. However, the relatively high volatile content of shergottites and some chondrites shows that the correlation is not simple; other factors must also be involved.

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USGS1980

Hydrocarbon gas in sediment from the shelf, slope and basin of the Bering Sea.

Methane, ethane, ethene, propane, propene, isobutane and n-butane are present in low concentrations in the top 2m of sediment. Methane is most abundant and its concentration increases with depth in the sediment. Ethane, ethene, propane and propene are present in almost all samples, but the concentrations of these gases are about two orders of magnitude-lower than the concentration of methane. The average ratios of ethane to ethene are usually greater than one in shelf sediment, about one in slope sediment, and usually less than one in basin sediments. These hydrocarbon gases are probably derived from low-temperature chemical and biochemical processes operating at or near the sea-floor. -from Authors

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USGS1980

Rate of mercury loss from contaminated estuarine sediments

The concentration of mercury in contaminated estuarine sediments of Bellingham Bay, Washington was found to decrease with a half-time of about 1.3 yr after the primary anthropogenic source of mercury was removed. In situ measurements of the mercury flux from sediments, in both dissolved and volatile forms, could not account for this decrease. This result suggests that the removal of mercury is associated with sediment particles transported out of the study area. This decrease was modeled using a steady-state mixing model. Mercury concentrations in anoxic interstitial waters reached 3.5 μg/l, 126 times higher than observed in the overlying seawater. Mercury fluxes from these sediments ranged from 1.2 to 2.8 × 10 −5 ng/cm 2 /sec, all in a soluble form. In general, higher Hg fluxes were associated with low oxygen or reducing conditions in the overlying seawater. In contrast, no flux was measurable from oxidizing interstitial water having mercury concentrations of 0.01-0.06 μ/l.

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USGS1980

Stable carbon isotopes of HCO3- in oil-field waters-implications for the origin of CO2

The δ 13 C values of dissolved HCO 3 − in 75 water samples from 15 oil and gas fields (San Joaquin Valley, Calif., and the Houston-Galveston and Corpus Christi areas of Texas) were determined to study the sources of CO 2 of the dissolved species and carbonate cements that modify the porosity and permeability of many petroleum reservoir rocks. The reservoir rocks are sandstones which range in age from Eocene through Miocene. The δ 13 C values of total HCO 3 − indicate that the carbon in the dissolved carbonate species and carbonate cements is mainly of organic origin. The range of δ 13 C values for the HCO 3 − of these waters is −20–28 per mil relative to PDB. This wide range of δ 13 C values is explained by three mechanisms. Microbiological degradation of organic matter appears to be the dominant process controlling the extremely low and high δ 13 C values of HCO 3 − in the shallow production zones where the subsurface temperatures are less than 80°C. The extremely low δ 13 C values (< −10 per mil) are obtained in waters where concentrations of SO 4 2− are more than 25 mg/l and probably result from the degradation of organic acid anions by sulfate-reducing bacteria ( SO 4 2− + CH 3 COO − → 2 HCO 3 − + HS − ). The high δ 13 C values probably result from the degradation of these anions by methanogenic bacteria ( CH 3 COO − + H 2 O ai HCO 3 − + CH 4 ). Thermal decarboxylation of short-chain aliphatic acid anions (principally acetate) to produce CO 2 and CH 4 is probably the major source of CO 2 for production zones with subsurface temperatures greater than 80°C. The δ 13 C values of HCO 3 − for waters from zones with temperatures greater than 100°C result from isotopic equilibration between CO 2 and CH 4 . At these high temperatures, δ 13 C values of HCO 3 − decrease with increasing temperatures and decreasing concentrations of these acid anions.

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USGS1980

Some factors controlling the concentration of uranium in the world ocean

Low-temperature alteration of the oceanic crust is a major sink for the U supplied to the oceans and may account for about 50% of the estimated present-day input of this element. Uranium uptake by organic-rich sediments and coexisting phosphorites on continental margins is also important and may remove in excess of 10% of the total supply. High-temperature alteration of oceanic basalts, metalliferous sediments, carbonate sediments, and sediments in anoxic basins deeper than 200 m play a relatively minor role in the removal of U. Each of these sinks is responsible for the uptake of less than 5% of the overall input.

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USGS1980

Deep-sea spherules from Pacific clay: Mass distribution and influx rate

From 411 kg of Pacific clay, 22 mg of stony spherules and 50 mg of iron spherules larger than 150 μm were concentrated. The extraterrestrial origin of these particles was evaluated with the aid of both optical and electron microscopy as well as atomic absorption elemental analysis. The integral number ( N ) of stony particles from this sediment in the mass (M) range 20–300 μg is given by N ( > M ( g )) = 5.13 × 10 −6 × M −1.65 . The world-wide influx rate of stony particles in the mass range which survive atmospheric heating and ocean sediment storage is calculated to be 90 tons/yr. The relative contributions of ablation debris vs fused interplanetary dust to the influx of stony spherules is discussed, but as yet the question remains unanswered.

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USGS1980

Rare earth element distribution in some hydrothermal minerals: Evidence for crystallographic control

Rare earth element (REE) abundances were measured by neutron activation analysis in anhydrite (CaSO 4 ), barite (BaSO 4 ), siderite (FeCO 3 ) and galena (PbS). A simple crystal-chemical model qualitatively describes the relative affinities for REE substitution in anhydrite, barite, and siderite. When normalized to ‘crustal’ abundances (as an approximation to the hydrothermal fluid REE pattern), log REE abundance is a surprisingly linear function of (ionic radius of major cation—ionic radius of REE) 2 for the three hydrothermal minerals, individually and collectively. An important exception, however, is Eu, which is anomalously enriched in barite and depleted in siderite relative to REE of neighboring atomic number and trivalent ionic radius. In principle, REE analyses of suitable pairs of co-existing hydrothermal minerals, combined with appropriate experimental data, could yield both the REE content and the temperature of the parental hydrothermal fluid. The REE have only very weak chalcophilic tendencies, and this is reflected by the very low abundances in galena—La, 0.6 ppb; Sm, 0.06 ppb; the remainder are below detection limits.

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USGS1981

U-Th-Pb systematics in hydrothermally altered granites from the Granite Mountains, Wyoming

U-Th-Pb systematics were investigated in 15 samples representing two types of deuterically altered Archean granite (albitized and silicified-epidotized granite) from the Granite Mountains, Wyoming. The loss of K-feldspar during both types of deuteric alteration was accompanied by an extreme reduction of Pb content from roughly 40 ppm to less than 12 ppm in the most altered samples. Nine of the 15 samples yield anomalously young whole-rock Pb-Pb and Th-Pb ages compared to concordia ages for zircons and to whole-rock Pb-Pb and Th-Pb ages for samples of unaltered granite. The young ages are interpreted to be the result of radiogenic Pb loss during a middle Proterozoic metamorphism that disturbed several isotopic systems in the unaltered granite. The loss of radiogenic Pb from the whole-rock systems of the deuterically altered granites is most likely due to the absence of microcline. In many granitic rocks, potassium feldspar tends to act as a receptor for Pb that has been mobilized, and this effect may account for the closed-system behavior of Pb in whole-rock samples of the unaltered granite. It may also account for the apparent gain of radiogenic Pb during the Proterozoic by one sample which was collected at the edge of an alteration zone. The deuterically altered granites may have also lost U during the Proterozoic, but, except for two samples, the dominant U loss occurred relatively recently, probably during Tertiary uplift and erosion. The low common-Pb contents and rather high U and Th contents of the hydrothermally altered granites might seem to indicate that these rocks are well suited for geochronologic studies in the U-Th-Pb system because such rocks should have a high percentage of radiogenic Pb. Unfortunately, open-system behavior in response to post-crystallization metamorphism shows that apparent ages for these types of rocks must be interpreted with caution.

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