Geology topics

J. R. O’Neil

Publications and source records attributed to J. R. O’Neil.

40 records · Page 3Linked to original sources

USGS1970

Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material

The water content of the breccia is 150 to 455 ppm, with a δD from—580 to —870 per mil. Hydrogen gas content is 40 to 53 ppm with a δD of —830 to —970 per mil. The CO 2 is 290 to 418 ppm with δ 13 C = + 2.3 to + 5.1 per mil and δ 18 O = 14.2 to 19.1 per mil. Non-CO 2 carbon is 22 to 100 ppm, δ 13 C = —6.4 to —23.2 per mil. Lunar dust is 810 ppm H 2 O (D = 80 ppm) and 188 ppm total carbon(δ 13 C = —17.6 per mil). The 18 O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100° to 1300°C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite.

Science↗

USGS1969

Oxygen isotope fractionation in divalent metal carbonates

Equilibrium fractionation factors for the distribution of 18 O between alkaline‐earth carbonates and water have been measured over the temperature range 0–500°C. The fractionation factors α"> α α can be represented by the equations CaCO3–H2O, 1000lnα = 2.78(106T−2)− 3.39,"> CaCO 3 – H 2 O , 1000 ln α = 2.78(10 6 T −2 )− 3.39, CaCO3–H2O, 1000lnα = 2.78(106T−2)− 3.39, SrCO3–H2O, 1000lnα = 2.69(106T−2)− 3.74,"> SrCO 3 – H 2 O , 1000 ln α = 2.69(10 6 T −2 )− 3.74, SrCO3–H2O, 1000lnα = 2.69(106T−2)− 3.74, BaCO3–H2O, 1000lnα = 2.57(106T−2)− 4.73."> BaCO 3 – H 2 O , 1000 ln α = 2.57(10 6 T −2 )− 4.73. BaCO3–H2O, 1000lnα = 2.57(106T−2)− 4.73. Measurements on MnCO 3 , CdCO 3 , and PbCO 3 were made at isolated temperatures. A statistical‐mechanical calculation of the isotopic partition function ratios gives reasonably good agreement with experiment. Both cationic size and mass are important in isotopic fractionation, the former predominantly in its effect on the internal vibrations of the anion, the latter in its effect on the lattice vibrations.

Journal of Chemical Physics↗

USGS1969

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. © 1969, The Geological Society of America, Inc.

Geological Society of America Bulletin↗

USGS1966

Uranium and lead isotopic stability in a metamict zircon under experimental hydrothermal conditions

Abstract. Disturbance of the uranium-lead isotopic system in a metamict Ceylon zircon has been produced in a 2 molal NaCI solution at 500°C and 1000 bars fluid pressure. Loss of radiogenic lead to the extent of 61 percent in 13 days was the most significant effect. The experimental results support the episodic rather than continuous lead-loss interpretation of natural zircon systems utilized in geochronology.

Science↗