Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (12) Citing Articles via Google Scholar Google Scholar Articles by Kessel, R. Articles by Thompson, A. B. Search for Related Content GeoRef GeoRef Citation

A novel approach to determine high-pressure high-temperature fluid and melt compositions using diamond-trap experiments

¹ Institut für Mineralogie und Petrographie, ETH-Zentrum, Zürich, Switzerland
² Institut für Isotopengeologie und Mineralische Rohstoffe, ETH-Zentrum, Zürich, Switzerland

Correspondence: ^* E-mail: kessel{at}erdw.ethz.ch

We have developed a novel analytical technique for diamond-trap experiments to directly analyze high-pressure, high-temperature fluid and melt compositions in equilibrium with mantle material. Experiments were conducted at a pressure of 6 GPa and temperatures between 900–1200 °C in a multi-anvil apparatus with a synthetic K-free eclogite doped with 860 ppm Cs, 20 wt% H₂O, and a layer of diamond aggregates serving as a fluid/melt trap. Experiments at identical conditions were analyzed with two different methods. In the new, "freezing," approach, the capsule was frozen prior to opening and kept frozen during laser-ablation ICP-MS analysis, thus ablating the quenched fluid (precipitates together with water that unmixed upon quenching) in a solid state. Cesium, fractionating completely into the fluid or melt phase, was used as an internal standard for calculating the fluid compositions. Calculated uncertainties on H₂O content in the fluid composition are 0.7–2.5%. In the conventional "evaporation" approach, water from the unmixed fluid was first evaporated from the capsule, then the remaining fluid precipitates were analyzed by LA-ICP-MS. The compositions of the residual eclogitic minerals were measured by electron microprobe, and the fluid composition was then determined by mass-balance. Uncertainties in mineral compositions lead to poor precision in fluid composition in this latter approach. Results of the two methods of fluid analysis were found to be in good agreement. Because the "freezing" approach analyzes the entire fluid directly and does not rely on mass balance for calculating fluid compositions, our new method provides a superior means for determining the composition of fluids. Secondly, it avoids loss of cations that remain soluble in water (e.g., Cs, K) after quenching the experiment.

This article has been cited by other articles:

				K. Klimm, J. D. Blundy, and T. H. Green Trace Element Partitioning and Accessory Phase Saturation during H2O-Saturated Melting of Basalt with Implications for Subduction Zone Chemical Fluxes J. Petrology, March 1, 2008; 49(3): 523 - 553. [Abstract] [Full Text] [PDF]

				A. C. Hack, A. B. Thompson, and M. Aerts Phase Relations Involving Hydrous Silicate Melts, Aqueous Fluids, and Minerals Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 129 - 185. [Full Text] [PDF]