High S and high CO 2 contents in haplokimberlite: An experimental and Raman spectroscopic study
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ORIGINAL PAPER
High S and high CO2 contents in haplokimberlite: An experimental and Raman spectroscopic study Yann Morizet 1 & Chloé Larre 1 & Ida Di Carlo 2 & Fabrice Gaillard 2 Received: 21 July 2019 / Revised: 25 May 2020 / Accepted: 1 June 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Sulfur is an important element present in natural kimberlites and along with CO2, S can play a role in the kimberlite degassing. We have investigated experimentally the change in S content and CO2 solubility in synthetic kimberlitic melts in response to a range of pressure (0.5 to 2.0 GPa) and temperature (1500 to 1525 °C). Several initial S concentrations were investigated ranging from 0 to 24000 ppm. The dissolved CO2 and S were determined by Raman spectroscopy and Electron Probe Micro-Analyses. Under the investigated oxidizing conditions (ΔFMQ + 1), S is dissolved in the glass only as S6+ forming sulfate molecular groups (SO42−). The measured S concentration in the glasses increases from 2900 to 22000 ppm. These results suggest that the experimental conditions were below saturation with respect to S and that the S solubility is higher than 22000 ppm for kimberlitic melts; regardless of the experimental conditions considered here. CO2 is dissolved as CO32− molecular groups. The CO2 solubility ranges from 3.0 to 11.3 wt% between 0.5 and 2.0 GPa. CO2 solubility is not affected by the presence of S; which suggests that SO42− and CO32− clusters have two distinct molecular environments not interacting together. This result implies that both CO2 and S are efficiently transported by kimberlitic melt from the upper mantle towards the atmosphere. Keywords Kimberlite . CO2 and S dissolution . Degassing
Introduction Volatiles are ubiquitous components in kimberlites. In particular, CO2 (and to a lesser extent H2O) has been shown to be an important volatile species involved in the dynamic and geochemistry of kimberlitic melts (Dawson 1971). Natural kimberlites exhibit relatively high CO 2 and H 2 O content (Kjarsgaard et al. 2009); and experimental studies have shown that CO2 solubility can be as high as 20 wt% in kimberlitic Editorial handling: C. Hauzenberger Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00710-020-00711-1) contains supplementary material, which is available to authorized users. * Yann Morizet [email protected] 1
Laboratoire de Planétologie et Géodynamique de Nantes (LPG), Université de Nantes, Nantes Atlantique Universités, UMR CNRS 6112, 2 rue de la Houssinière, 44322 Nantes Cedex, France
2
CNRS/INSU-Université d’Orléans – BRGM, UMR 7327, Institut des Sciences de la Terre d’Orléans, 1A rue de la Férollerie, 45071 Orléans, France
glasses synthesized under mantle pressure conditions (Brey and Ryabchikov 1994; Girnis et al. 2005). Under lower crustal pressure conditions H2O solubility is comparable to the H2O solubility observed in basalts (Moussallam et al. 2016). Up to now, the potentiality for sulfur (S) to play a significant r
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