Experimental tests on achieving equilibrium in synthetic fluid inclusions: Results for scheelite, molybdenite, and gold solubility at 800 °C and 200 MPa

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dc.identifier.uri http://dx.doi.org/10.15488/1255
dc.identifier.uri http://www.repo.uni-hannover.de/handle/123456789/1280
dc.contributor.author Derrey, Insa Theresa
dc.contributor.author Albrecht, Moritz
dc.contributor.author Dupliy, Eygeniya
dc.contributor.author Botcharnikov, Roman E.
dc.contributor.author Horn, Ingo
dc.contributor.author Junge, Malte
dc.contributor.author Weyer, Stefan
dc.contributor.author Holtz, Francois
dc.date.accessioned 2017-04-05T12:01:21Z
dc.date.available 2018-02-01T23:05:22Z
dc.date.issued 2017
dc.identifier.citation Derrey, I.T.; Albrecht, M.; Dupliy, E.; Botcharnikov, R.E.; Horn, I.; et al.: Experimental tests on achieving equilibrium in synthetic fluid inclusions: Results for scheelite, molybdenite, and gold solubility at 800 °C and 200 MPa. In: American Mineralogist 102 (2017), Nr. 2, S. 275-283. DOI: https://doi.org/10.2138/am-2017-5869
dc.description.abstract Synthetic fluid inclusions formed in high P-T experiments, which are subsequently analyzed with LA-ICP-MS, enable us to collect thermodynamic data to constrain metal transport in aqueous fluids as well as partitioning of metals between coexisting phases. The most essential prerequisite for such studies is to ensure that equilibrium conditions between liquid and solid phases are reached prior to the formation of synthetic fluid inclusions in the host mineral. Various methods have been proposed by different authors to achieve this goal, but to this point our knowledge on the best approach to synthesize equilibrated fluid inclusions under constrained pressure, temperature, and compositional (P, T, and X) conditions remains poor. In addition, information on the time needed to reach equilibrium metal concentrations in the fluid as well as on the timing of the onset of fluid inclusion formation in the host mineral are scarce. The latter has been tested in a series of time-dependent experiments at 800 °C and 200 MPa using scheelite (CaWO4), molybdenite (MoS2) and metallic gold as dissolving phases and using different approaches to optimize the formation of equilibrated fluid inclusions. Both Embedded Image and Embedded Image were fixed during all experiments using the pyrite-pyrrhotite-magnetite buffer (PPM). As an intermediate in situ quenching of the sample charge plays an important role in the synthesis of fluid inclusions, we further tested the efficiency of such an intermediate quench for re-opening fluid inclusions formed at 600 °C and 200 MPa. Our results reveal that fluid inclusions start forming almost instantaneously and that equilibrium between fluid and solid phases occurs in the timescale of less than two hours for molybdenite and gold up to ca. 10 h for scheelite. The best approach to synthesize equilibrated fluid inclusions at 800 °C was obtained by using an intermediate quench on a previously unfractured quartz host. Experiments at 600 °C showed similar results and illustrate that this should be the method of choice down to this temperature. Below 600 °C pre-treatment of the quartz host (HF etching and/or thermal fracturing) becomes important to produce large enough fluid inclusions for the analyses via LA-ICP-MS and special care must be taken to prevent premature entrapment of the fluid. Fluids with 8 wt% NaCl in equilibrium with scheelite, molybdenite and gold at 800 °C and 200 MPa have concentrations of ca. 7300 ppm W, 1300 ppm Mo, and 300 ppm Au, respectively, which is in good agreement with results from other studies or extrapolation from lower temperatures. It can be concluded that the formation of synthetic fluid inclusions from an equilibrated fluid is possible, but different experimental designs are required, depending on the investigated temperature. In general, dissolution of solid phases seems to be much faster than previously assumed, so that experimental run durations can be designed considerably shorter, which is of great advantage when using fast-consuming mineral buffers. eng
dc.description.sponsorship State of Lower Saxony
dc.description.sponsorship Graduate School GeoFluxes
dc.description.sponsorship Leibniz Universität Hannover
dc.language.iso eng
dc.publisher Berlin : Walter de Gruyter
dc.relation.ispartofseries American Mineralogist 102 (2017), Nr. 2
dc.rights Es gilt deutsches Urheberrecht. Das Dokument darf zum eigenen Gebrauch kostenfrei genutzt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden.
dc.subject equilibrium eng
dc.subject gold solubility in aqueous fluid eng
dc.subject molybdenite solubility in aqueous fluid eng
dc.subject scheelite solubility in aqueous fluid eng
dc.subject Synthetic fluid inclusions eng
dc.subject.ddc 550 | Geowissenschaften ger
dc.title Experimental tests on achieving equilibrium in synthetic fluid inclusions: Results for scheelite, molybdenite, and gold solubility at 800 °C and 200 MPa
dc.type Text
dc.type article
dc.relation.issn 0003-004X
dc.relation.doi https://doi.org/10.2138/am-2017-5869
dc.bibliographicCitation.issue 2
dc.bibliographicCitation.volume 102
dc.bibliographicCitation.firstPage 275
dc.bibliographicCitation.lastPage 283
dc.description.version acceptedVersion
tib.accessRights frei zug�nglich


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