Articles | Volume 34, issue 2
https://doi.org/10.5194/ejm-34-201-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/ejm-34-201-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
31 Mar 2022
Research article |
| 31 Mar 2022
| 31 Mar 2022
In situ reinvestigation of reaction phase A plus high-pressure clinoenstatite to forsterite plus water in the system MgO-SiO2-H2O (MSH)
Christian Lathe
Department Geochemistry, Deutsches GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany
DESY, Deutsches Elektronen Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
Monika Koch-Müller
Department Geochemistry, Deutsches GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany
Bernd Wunder
CORRESPONDING AUTHOR
Department Geochemistry, Deutsches GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany
Oona Appelt
Department Geochemistry, Deutsches GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany
Shrikant Bhat
DESY, Deutsches Elektronen Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
Robert Farla
DESY, Deutsches Elektronen Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany
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Catherine Leyx, Peter Schmid-Beurmann, Fabrice Brunet, Christian Chopin, and Christian Lathe
Eur. J. Mineral., 36, 417–431, https://doi.org/10.5194/ejm-36-417-2024, https://doi.org/10.5194/ejm-36-417-2024, 2024
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This paper presents the results of an exploratory study on the pressure–volume–temperature behaviour of the main Mg-phosphates of geological interest, especially in high-pressure metamorphic rocks. The incentive for it was the growing body of experimental phase-equilibrium data acquired at high pressure in the MgO–(Al2O3)–P2O5–H2O systems, the thermodynamic evaluation of which has been begging for such volumetric data.
Dirk Spengler, Monika Koch-Müller, Adam Włodek, Simon J. Cuthbert, and Jarosław Majka
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West Norwegian 'diamond facies' eclogite contains tiny mineral inclusions of quartz and amphibole lamellae that are not stable in the diamond field. Low trace amounts of water in the lamellae-bearing host minerals suggest that the inclusion microstructure was not formed by fluid infiltration but by dehydration during early exhumation of these rocks. Some samples with higher water content argue that a late fluid overprint was spatially restricted and obliterated evidence of extreme metamorphism.
Catherine Leyx, Peter Schmid-Beurmann, Fabrice Brunet, Christian Chopin, and Christian Lathe
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This paper presents the results of an exploratory study on the pressure–volume–temperature behaviour of the main Mg-phosphates of geological interest, especially in high-pressure metamorphic rocks. The incentive for it was the growing body of experimental phase-equilibrium data acquired at high pressure in the MgO–(Al2O3)–P2O5–H2O systems, the thermodynamic evaluation of which has been begging for such volumetric data.
Alessia Borghini, Silvio Ferrero, Patrick J. O'Brien, Bernd Wunder, Peter Tollan, Jarosław Majka, Rico Fuchs, and Kerstin Gresky
Eur. J. Mineral., 36, 279–300, https://doi.org/10.5194/ejm-36-279-2024, https://doi.org/10.5194/ejm-36-279-2024, 2024
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We studied primary granitic and halogen-rich melt inclusions trapped in mantle rocks in the Bohemian Massif (Germany) in order to retrieve important information about the nature of the melt and the source rock. The melt was produced by the partial melting of metasediments during the deepest stages of subduction and interacted with the mantle. This work is an excellent example of transfer of crustal material, volatiles in particular, in the mantle during the subduction of the continental crust.
Christian Lathe, Monika Koch-Müller, Bernd Wunder, Oona Appelt, Melanie Sieber, Shrikant Bhat, and Robert Farla
Eur. J. Mineral., 35, 1149–1157, https://doi.org/10.5194/ejm-35-1149-2023, https://doi.org/10.5194/ejm-35-1149-2023, 2023
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We examined the reaction phase A plus high-P clinoenstatite to forsterite plus water (Reaction 1) by means of in situ X-ray diffraction measurements with the large volume press at the synchrotron PETRA III, Hamburg. Contrary to other studies, in which all experiments on Reaction (1) were performed at a water activity of 1, the reversed experiments presented in this study were performed at reduced water activity with mole fractions of about XH2O = XCO2 = 0.5.
Silvio Ferrero, Alessia Borghini, Laurent Remusat, Gautier Nicoli, Bernd Wunder, and Roberto Braga
Eur. J. Mineral., 35, 1031–1049, https://doi.org/10.5194/ejm-35-1031-2023, https://doi.org/10.5194/ejm-35-1031-2023, 2023
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Garnet often entraps small droplets of deep melts generated during mountain building processes. Using high-resolution techniques, we studied these droplets in order to provide hard numbers for the quantification of volatile budgets during crustal evolution, show how even melts formed at >1000°C contain water, and clarify how water behaves during metamorphism and melting at the microscale. Moreover, we provide the very first data on chlorine in natural melts from crustal reworking.
Mary Robles, Odile Peyron, Guillemette Ménot, Elisabetta Brugiapaglia, Sabine Wulf, Oona Appelt, Marion Blache, Boris Vannière, Lucas Dugerdil, Bruno Paura, Salomé Ansanay-Alex, Amy Cromartie, Laurent Charlet, Stephane Guédron, Jacques-Louis de Beaulieu, and Sébastien Joannin
Clim. Past, 19, 493–515, https://doi.org/10.5194/cp-19-493-2023, https://doi.org/10.5194/cp-19-493-2023, 2023
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Quantitative climate reconstructions based on pollen and brGDGTs reveal, for the Late Glacial, a warm Bølling–Allerød and a marked cold Younger Dryas in Italy, showing no latitudinal differences in terms of temperatures across Italy. In terms of precipitation, no latitudinal differences are recorded during the Bølling–Allerød, whereas 40–42° N appears as a key junction point between wetter conditions in southern Italy and drier conditions in northern Italy during the Younger Dryas.
Melanie J. Sieber, Max Wilke, Oona Appelt, Marcus Oelze, and Monika Koch-Müller
Eur. J. Mineral., 34, 411–424, https://doi.org/10.5194/ejm-34-411-2022, https://doi.org/10.5194/ejm-34-411-2022, 2022
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Carbonates reduce the melting point of the mantle, and carbonate melts produced in low-degree melting of a carbonated mantle are considered the precursor of CO2-rich magmas. We established experimentally the melting relations of carbonates up to 9 GPa, showing that Mg-carbonates melt incongruently to periclase and carbonate melt. The trace element signature of carbonate melts parental to kimberlites is approached by melting of Mg-rich carbonates.
Monika Koch-Müller, Oona Appelt, Bernd Wunder, and Richard Wirth
Eur. J. Mineral., 33, 675–686, https://doi.org/10.5194/ejm-33-675-2021, https://doi.org/10.5194/ejm-33-675-2021, 2021
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Dense hydrous magnesium silicates, like the 3.65 Å phase, are thought to cause deep earthquakes. We investigated the dehydration of the 3.65 Å phase at P and T. In both directions of the investigated simple reaction, additional metastable water-rich phases occur. The observed extreme reduction in grain size in the dehydration experiments might cause mechanical instabilities in the Earth’s mantle and, finally, induce earthquakes.
Nada Abdel-Hak, Bernd Wunder, Ilias Efthimiopoulos, and Monika Koch-Müller
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The structural response of the NH4+ molecule to temperature and pressure changes is studied in ammonium phengite. The symmetry of the molecule is lowered by increasing P or decreasing T; the type and mechanism of this lowered symmetry is different in both cases. Devolatilisation (NH4+ and OH loss) of ammonium phengite is studied as well. This study confirms the wide stability range of phengite and its volatiles and thus has important implications for N and H recycling into the deep Earth.
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High-pressure study of minerals
The use of MgO–ZnO ceramics to record pressure and temperature conditions in the piston–cylinder apparatus
The miscibility gap between the rock salt and wurtzite phases in the MgO–ZnO binary system to 3.5 GPa
High-pressure and high-temperature structure and equation of state of Na3Ca2La(CO3)5 burbankite
Melt–rock interactions in a veined mantle: pyroxenite–peridotite reaction experiments at 2 GPa
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Nicholas Farmer and Hugh St. C. O'Neill
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The piston–cylinder apparatus is widely used to investigate rock properties at the conditions of the interior of the Earth, but uncertainty in its calibration of pressure persists, with substantial differences between laboratories. We use a ceramic of magnesium and zinc oxides to measure the conditions experienced by a sample. Routine use of such ceramics provides an archive of experimental conditions, enables interlaboratory comparisons, and resolves long-standing controversies in calibration.
Nicholas Farmer and Hugh St. C. O'Neill
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The chemical compositions of the synthetic minerals periclase and zincite in the MgO–ZnO binary system change smoothly and systematically with pressure when they exist together in equilibrium. We have studied these changes experimentally over a wide range of conditions and fitted the results to a thermodynamic model. The model may be used to predict the compositions of the coexisting phases accurately at high pressures and temperatures corresponding to the Earth’s crust and uppermost mantle.
Sula Milani, Deborah Spartà, Patrizia Fumagalli, Boby Joseph, Roberto Borghes, Valentina Chenda, Juliette Maurice, Giorgio Bais, and Marco Merlini
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This work presents new thermoelastic parameters and the structural evolution of burbankite at high pressure and high temperature, obtained by in situ synchrotron radiation single-crystal diffraction measurements. Burbankite is a carbonate that may potentially play a key role as an upper-mantle reservoir of light REE3+. We observed that the density of burbankite is greater with respect to carbonatitic magmas, indicating a possible fractionation of this phase in upper-mantle conditions.
Giulio Borghini, Patrizia Fumagalli, and Elisabetta Rampone
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The mineralogical and chemical heterogeneity of the mantle is poorly known because it is not able to be directly investigated. Melt–peridotite interaction processes play a fundamental role in controlling the mantle composition. The results of our reaction experiments help us to evaluate the role of temperature and melt composition in the modification of the mantle through the interaction with pyroxenite-derived melts with implications for the evolution of a veined mantle.
Monika Koch-Müller, Oona Appelt, Bernd Wunder, and Richard Wirth
Eur. J. Mineral., 33, 675–686, https://doi.org/10.5194/ejm-33-675-2021, https://doi.org/10.5194/ejm-33-675-2021, 2021
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Dense hydrous magnesium silicates, like the 3.65 Å phase, are thought to cause deep earthquakes. We investigated the dehydration of the 3.65 Å phase at P and T. In both directions of the investigated simple reaction, additional metastable water-rich phases occur. The observed extreme reduction in grain size in the dehydration experiments might cause mechanical instabilities in the Earth’s mantle and, finally, induce earthquakes.
Jeffrey P. Gay, Lowell Miyagi, Samantha Couper, Christopher Langrand, David P. Dobson, Hanns-Peter Liermann, and Sébastien Merkel
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We examined the experimental deformation and phase transition of a bridgmanite analogue, NaCoF3, using a resistive-heated diamond anvil cell and a synchrotron radiation source. We wanted to observe the behavior of NaCoF3 under uniaxial compression and its plastic properties, as well as to determine if it is a suitable analogue for natural samples. We observe 100 and 001 compression textures and link those to the dominant deformation mechanism in the perovskite structure.
Nicole Biedermann, Elena Bykova, Wolfgang Morgenroth, Ilias Efthimiopoulos, Jan Mueller, Georg Spiekermann, Konstantin Glazyrin, Anna Pakhomova, Karen Appel, and Max Wilke
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Carbonates play a key role in the chemistry and dynamics of our planet. The role of SrCO3 in the deep mantle has received little attention due to its low abundance. However, knowing the high-pressure phase behaviour of natural carbonates across its full compositional range is essential to evaluate effects of chemical substitution in the system of deep-Earth carbonates. We performed powder and single-crystal X-ray diffraction up to 49 GPa and observed a phase transition in SrCO3 at around 26 GPa.
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Short summary
The equilibrium phase of A + HP clinoenstatite = forsterite + water was experimentally investigated at aH2O = 1 in situ. In cold subducting slabs, it is of relevance to transport water to large depths, initiating the formation of dense hydrous magnesium silicate (DHMS). At normal gradients, the huge water amount from this reaction induces important processes within the overlying mantle wedge. We additionally discuss the relevance of this reaction for intermediate-depth earthquake formation.
The equilibrium phase of A + HP clinoenstatite = forsterite + water was experimentally...
