Useful references for Gas Bench samples
δD and δ18O variations in the Ocean and Atomosphere.
Craig, H., and L. I. Gordon (1965) Deuterium and oxygen 18 variations in the ocean and marine atmosphere. In proc. Stable Isotopes in Oceanographic Studies and Paleotemperatures, 1965, Spoleto, Italy. edited by E. Tongiogi, pp 9-130, V. Lishi e F., Pisa.
δD and δ18O Databases.
Salt Effect on CO2 - H2O equilibration.
Feder H. M. and Taube H. (1952) Ionic hydration: An isotopic fractionation technique. J. Chem. Phys. 20, 1335-1336
Taube H. (1954) Use of oxygen isotope effects in the study of hydration of ions. J. Phys. Chem. 58, 523-528
Truesdell A.H. Oxygen isotope activities and concentrations in aqueous salt solutions at elevated temperatures: consequences for isotope geochemistry. Earth. Plan. Sci. Lett., 1974, v.23, pp.387-396.
Horita J. Stable isotope fractionation factors of water in hydrated saline mineral-brine systems. Earth. Plan. Sci. Lett., 1989, v.95, pp. 173-179.
Horita J. The effect of dissolved NaCl and KCl on oxygen and hydrogen isotope fractionation between water vapor and brines at 50-100 C. GSA abstracts, 1991, v.23, n.5, p. A320-A321.
Horita J., Wesolowski D.J., Cole D.R. The effects of dissolved salts on oxygen and hydrogen isotope fractionation between water vapor and brines at 50-100 C. Proceedings of 7th international Water-Rock Interaction Conf.
Poulson S.R., Schoonen M.A., Ohmoto H. oxygen isotope fractionation between free water and hydration sphere water in NaCl solutions from 100 degrees to 300 degrees centigrade. GSA abstracts, 1991, v.23, n.5, p. A320-A321.
Zhang Ligang, Liu Jingxiu, Zhou Huanbo, Chen Zhensheng. Oxygen isotope fractionation in quartz-water-salt system. In: Petrogenetic and Minerogenetic theories and prospecting, 1989, Press of Beijing University of Technology, pp. 177-188.
Usdowski E., Hoefs J. Kinetic 13C/12C and 18O/16O effects upon dissolution and outgassing of CO2 in the system CO2-H2O. Chem. Geol., 1990, v.80, pp. 109-118.
Exetainer vial considerations.Nelson, S.T.,Sample vial influences on the accuracy and precision of carbon and oxygen isotope ratio analysis in continuous flow mass spectrometric applications, 2000, Rapid Communications in Mass Spectrometry, v. 4, p. 293-297.
Dolomites on the Gas Bench.
The simple hand test to distinguish dolomite from calcite is to apply some hydrochloric acid (12M conc diluted 1+9). Dolomite is NOT soluble in dilute HCl.
If the powdered mineral is pre-acidified in an open vessel with dilute (1M or less) HCl, then the powder left after careful washing with distilled/deionized water would be dolomite. The acid is added until all evolution of CO2 bubbles stops, it may take some shaking to expose all the grains to the acid, but heating should be avoided.
One would do this on a 5 gram bulk powder sample in test tubes. This makes it easy to rinse multiple times, centrifuging and decanting each rinse. Dry carefully at 60C, and THEN weigh into vials for GasBench treatment with phosphoric acid. And remember that the fractionation of dolomite is different than calcite...
I believe that this separation method has appeared in older journals of mineralogical analysis of dolomite-calcite mixtures, comparing the results with X-ray diffraction analysis of the same powder. The goal was NOT isotope analysis but the end result was an effective separation.Irene Ellis
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