| Abstract: | The ??18O of ground water (-13.54 ?? 0.05 ???) and inorganically precipitated Holocene vein calcite (+14.56 ?? 0.03 ???) from Devils Hole cave #2 in southcentral Nevada yield an oxygen isotopic fractionation factor between calcite and water at 33.7 ??C of 1.02849 ?? 0.00013 (1000 ln ??calcite-water = 28.09 ?? 0.13). Using the commonly accepted value of ???(??calcite-water)/???T of -0.00020 K-1, this corresponds to a 1000 ln ??calcite-water value at 25 ??C of 29.80, which differs substantially from the current accepted value of 28.3. Use of previously published oxygen isotopic fractionation factors would yield a calcite precipitation temperature in Devils Hole that is 8 ??C lower than the measured ground water temperature. Alternatively, previously published fractionation factors would yield a ??18O of water, from which the calcite precipitated, that is too negative by 1.5 ??? using a temperature of 33.7 ??C. Several lines of evidence indicate that the geochemical environment of Devils Hole has been remarkably constant for at least 10 ka. Accordingly, a re-evaluation of calcite-water oxygen isotopic fractionation factor may be in order. Assuming the Devils Hole oxygen isotopic value of ??calcite-water represents thermodynamic equilibrium, many marine carbonates are precipitated with a ??18O value that is too low, apparently due to a kinetic isotopic fractionation that preferentially enriches 16O in the solid carbonate over 18O, feigning oxygen isotopic equilibrium. |
| Genre: | Article |
| ProdID: | 70030756 |
| Citation Author: | Coplen, T. B. |
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| Citation End Page: | 3957 |
| Citation Issue: | 16 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geochimica et Cosmochimica Acta |
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| Citation Number Of Pages: | 10 |
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| Citation Search Results Text: | Calibration of the calcite-water oxygen-isotope geothermometer at Devils Hole, Nevada, a natural laboratory; 2007; Article; Journal; Geochimica et Cosmochimica Acta; Coplen, T. B. |
| Citation Start Page: | 3948 |
| Citation Volume: | 71 |
| Citation Year: | 2007 |
| Type: | citation/reference |
| Text: | Calibration of the calcite-water oxygen-isotope geothermometer at Devils Hole, Nevada, a natural laboratory; 2007; Article; Journal; Geochimica et Cosmochimica Acta; Coplen, T. B. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1016/j.gca.2007.05.028 |
| Date Other: | Mon, 1 Jan 2007 00:00 -0600 |
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