Ivan Barnes

The Relationship between Fluids in Some Fresh Alpine-Type Ultramafics and Possible Modern Serpentinization, Western United States

Calcium hydroxide waters issue from four partly serpentinized Alpine-type ultramafic bodies in the western United States. The occurrence of calcium-hydroxide-type water is restricted to fresh Alpine-type ultramafic rocks. The calcium hydroxide waters are unsaturated with Mg end-member olivine and pyroxene but supersaturated with Mg end-member brucite and serpentine and thus have chemical potentials to cause Serpentinization. The calcium hydroxide waters are isotopically similar to the common magnesium bicarbonate meteoric waters peculiar to ultramafic rocks and serpentinites. Some Serpentinization is apparently a near-surface phenomenon occurring at present. The Serpentinization takes place at nearly constant composition, except for loss of CaO.

Present day serpentinization in New Caledonia, Oman and Yugoslavia

Abstract 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 18 O content of serpentine formed at low temperatures is in part inherited from the pyroxene and olivine.

Geochemical Evidence of Present-Day Serpentinization

Ultrabasic (pH > 11) water issues from some fresh ultramafic bodies. The properties of the ultrabasic solutions are believed to be due to current reactions yielding serpentine from primary olivines and pyroxenes. The low concentrations of divalent airon. divalent magnesium, and dissolved silica from the serpentinization require an increase in rock volume.

C13 and O18 compositions in some fresh-water carbonates associated with ultramafic rocks and serpentinites: western United States☆

All carbonates associated with the ultramafic rocks and serpentinites of the western United States are shown by their stable isotope ratios to be of near-surface, low-temperature origin. These include vein materials that have been previously classified as hydrothermal. New laboratory and natural data were obtained on the equilibrium isotope relations between hydromagnesite and water. The origins of travertines in the ultramafic area are easily distinguished on the basis of their stable isotope ratios. The extremely heavy isotope ratios of nesquehonites suggest an intricate evaporating-film mechanism of formation.

Short chain aliphatic acid anions in oil field waters and their contribution to the measured alkalinity

Abstract High alkalinity values found in some formation waters from Kettleman North Dome oil field are due chiefly to acetate and propionate ions, with some contribution from higher molecular weight organic acid ions. Some of these waters contain no detectable bicarbonate alkalinity. For waters such as these, high supersaturation with respect to calcite will be incorrectly indicated by thermodynamic calculations based upon carbonate concentrations inferred from traditional alkalinity measurements

Geochemistry of Birch Creek, Inyo County, California a travertine depositing creek in an arid climate

Abstract A small stream in eastern California was studied in detail to determine the causes of travertine deposition from the stream. Although the ground water feeding the stream is slightly supersaturated to just saturated with calcite, the ground water is supersaturated with CO2 with respect to the overlying air. The water becomes increasingly supersaturated with calcite in a downstream direction as CO2 loss to the air and by photosynthesis exceeds the rate of precipitation of calcite. Water loss by evaporation was below detection and does not play an important role in calcite deposition in this case. The water loss is by seepage through the stream bed. Observations showed variations in HCO−3, pH, discharge, Ca+2, relative humidity, water and air temperatures, and dissolved CO2. Comparisons of observed and equilibrium states are given for five sampling stations along the stream.

Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements and travertines in the Coast Range of California

Abstract Two calcium-magnesium carbonate solid solutions form Holocene travertines and conglomerate cements in fresh water stream channels of the Coast Range of California. Calcite does not yield the {015} diffraction maximum. The {006} diffraction maximum is lacking over most of the range of composition of calcite. Calcite has compositions from CaCO3 to Ca0.5Mg0.5CO3. Dolomite yields both the {006} and {015} diffraction maxima over its entire composition range, Ca0.6Mg0.4CO3 to Ca0.5Mg0.5CO3. The Ca-Mg carbonates form in isotopic equilibrium and thermodynamic disequilibrium from dispersion of Ca2+-rich water into CO32−-rich water within the alluvium. The stable isotope data suggest that all the Mg-rich carbonates are primary precipitates and not a result of Mg-substitution in precursor CaCO3. There is a correlation between δC13 and Mg content of the carbonates which predicts a 5%. fractionation of C13 between dolomite and calcite at sedimentary temperatures. C14 is incorporated in Ca-Mg carbonates forming from C13-poor meteoric waters and C13-rich waters from Cretaceous sediments. C14 ages of the Ca-Mg carbonates are apparent, and cannot be corrected to absolute values. Solution rates of calcite decrease with increasing MgCO3 content; dolomite dissolves slower than any calcite.

Metamorphic waters from the pacific tectonic belt of the west coast of the United States.

Waters unusually rich in ammonia, boron, carbon dioxide, hydrogen sulfide, and hydrocarbons are found in more than 100 localities along the Pacific coast of the United States. The waters are believed to be products of low-grade metamorphism of marine sediments. The marine sedimentary rocks would have to be tectonically emplaced below crystalline rocks in many places. Mercury ore deposits are probably also products of the low-grade metamorphism.

Possible role of mantle-derived CO2 in causing two “phreatic” explosions in Alaska

Two “phreatic” maars in Alaska may have been created by the explosive release of carbon dioxide from a basaltic melt. Both the basalt of the maars and the observed CO 2 (δ 13 C = −6.36‰) are inferred to have come from the mantle.

Geochemistry of highly basic calcium hydroxide groundwater in Jordan

Abstract Highly-alkaline (pH > 12.5) meteoric waters of a Ca2+OH−-type issue from naturally calcined bituminous marl. The cold (16.5 ≤ T(°C) ≤ 19.1) waters are super-saturated with minerals thought to be of high-temperature origin.