Periodic Reporting for period 1 - ELASTIC (The effect of Fe, Al and Ti on the density, elasticity and the post-stishovite transition of eclogitic H2O-bearing stishovite: Implications on the observability of seismic anomalies in Earth’s mantle)
Reporting period: 2020-09-01 to 2023-08-31
ELASTIC is aimed at determining the effect of incorporating typical eclogitic defects (Al, Ti, Fe, OH) on the high-pressure-temperature phase diagram, density, structure and elasticity of defective stishovite. To this end, a series of in situ high pressure, high temperature ultrasonic runs with various defective stishovites have been conducted. These cover geologically relevant pressure and temperature conditions near the anticipated transition (see figure). The combination of a high-density of diffraction and ultrasonic data has enabled the rutile-CaCl2 phase transition to be located precisely and evaluated across a wide range of high-pressure and high-temperature conditions.
This study provides directly measured density and sound velocity measurements and thus, enables better experimental constraints of bulk elastic properties and their pressure and temperature derivatives of eclogitic stishovite at mantle-relevant pressure and temperature conditions. This study extends information essential to the interpretation of the seismic observables, and contributes to more complete modelling of subducted oceanic crustal material inside the Earth’s deep mantle. The results allow improvements to fundamental models used to predict and determine seismic anomalies caused by recycled subducted material through the Earth's mantle, particularly in the upper part of the lower mantle.
This study provides directly measured density and sound velocity measurements and thus, enables better experimental constraints of bulk elastic properties and their pressure and temperature derivatives of eclogitic stishovite at mantle-relevant pressure and temperature conditions. This study extends information essential to the interpretation of the seismic observables, and contributes to more complete modelling of subducted oceanic crustal material inside the Earth’s deep mantle. The results allow improvements to fundamental models used to predict and determine seismic anomalies caused by recycled subducted material through the Earth's mantle, particularly in the upper part of the lower mantle.
Completion of Strand 1:
A range of defective stishovite samples with varying amounts of Al, Fe, Ti and H2O were synthesised at beamline ID06-LVP, ESRF at 15-32 GPa and ~1200-1400 ºC from glasses, using a 10/5, 10/4 and 7/3 multianvil assemblies.
Recovered samples were examined by optical microscope, SEM at ESRF, and EPMA at ISTerre, UGA, France. Samples were double-polished for SMS at ID18 (now ID14), ESRF.
Completion of Strand 2:
Stishovites recovered from Strand 1 were double-polished (~0.5 mm thick) for these measurements. Combined in-situ X-ray diffraction and ultrasonic interferometry, using 10/4 and 7/3 geometries, were successfully conducted at ID06-LVP to ~ 32 GPa and 1800 K.
Deviations and limitations of Strand 1 & 2:
The recovered stishovites exhibited a very small grain size. This resulted in the inability to apply H2O measurements using Fourier Transform Infrared Spectroscopy and Nanoscale Secondary Ion Mass Spectrometry. Some Fe³⁺/ΣFe determinations of the samples were successfully conducted during the course of the project, with the use of allocated beamtime at ID18, but will be improved with access to the new ID14.
Exploitation and dissemination of the results:
The findings of this study have thus far been disseminated to the scientific community at large, at six international conferences, comprising five oral presentations and one poster presentation.
The outcomes of this study were presented at the International Diamond School, Italy, in 2023, as well as in the context of four formal meetings as three oral presentations held at the ESRF (2021, 2022 and 2023). These meetings included presentations given at the ID06-LVP Beamline Review (2021), and at the Matter at Extremes Group Day Out (2022, 2023).
Publications without peer-reviewed conference proceedings: Conference abstracts in conjugation with an oral presentation (=11) or a poster presentations (=1)
Communication activities:
The outcomes of this research were also transmitted to the scientific community and community at large, particular at beamline ID06-LVP and also at beamline ID18 (now ID14), ESRF. At these facilities, numerous research user groups from diverse scientific disciplines, including crystallography, mineral physics, geosciences, physics, chemistry, and medicine, conduct studies during allocated beamtime. In light of the recent developments in combined in-situ X-ray diffraction, imaging and pulse-echo ultrasonic high-pressure experimentation using the large volume press at the ID06-beamline, key advances and achievements of the course of the researcher’s project were constantly undertaken with the aim of raising awareness of the research undertaken, in a similar manner to that which has been done during the aforementioned international conferences and other formal meetings. This resulted in the formation of new collaborations and the fostering of ongoing ones, as well as the attraction of new research user groups to the ID06 and ID14/ID18 beamlines.
A range of defective stishovite samples with varying amounts of Al, Fe, Ti and H2O were synthesised at beamline ID06-LVP, ESRF at 15-32 GPa and ~1200-1400 ºC from glasses, using a 10/5, 10/4 and 7/3 multianvil assemblies.
Recovered samples were examined by optical microscope, SEM at ESRF, and EPMA at ISTerre, UGA, France. Samples were double-polished for SMS at ID18 (now ID14), ESRF.
Completion of Strand 2:
Stishovites recovered from Strand 1 were double-polished (~0.5 mm thick) for these measurements. Combined in-situ X-ray diffraction and ultrasonic interferometry, using 10/4 and 7/3 geometries, were successfully conducted at ID06-LVP to ~ 32 GPa and 1800 K.
Deviations and limitations of Strand 1 & 2:
The recovered stishovites exhibited a very small grain size. This resulted in the inability to apply H2O measurements using Fourier Transform Infrared Spectroscopy and Nanoscale Secondary Ion Mass Spectrometry. Some Fe³⁺/ΣFe determinations of the samples were successfully conducted during the course of the project, with the use of allocated beamtime at ID18, but will be improved with access to the new ID14.
Exploitation and dissemination of the results:
The findings of this study have thus far been disseminated to the scientific community at large, at six international conferences, comprising five oral presentations and one poster presentation.
The outcomes of this study were presented at the International Diamond School, Italy, in 2023, as well as in the context of four formal meetings as three oral presentations held at the ESRF (2021, 2022 and 2023). These meetings included presentations given at the ID06-LVP Beamline Review (2021), and at the Matter at Extremes Group Day Out (2022, 2023).
Publications without peer-reviewed conference proceedings: Conference abstracts in conjugation with an oral presentation (=11) or a poster presentations (=1)
Communication activities:
The outcomes of this research were also transmitted to the scientific community and community at large, particular at beamline ID06-LVP and also at beamline ID18 (now ID14), ESRF. At these facilities, numerous research user groups from diverse scientific disciplines, including crystallography, mineral physics, geosciences, physics, chemistry, and medicine, conduct studies during allocated beamtime. In light of the recent developments in combined in-situ X-ray diffraction, imaging and pulse-echo ultrasonic high-pressure experimentation using the large volume press at the ID06-beamline, key advances and achievements of the course of the researcher’s project were constantly undertaken with the aim of raising awareness of the research undertaken, in a similar manner to that which has been done during the aforementioned international conferences and other formal meetings. This resulted in the formation of new collaborations and the fostering of ongoing ones, as well as the attraction of new research user groups to the ID06 and ID14/ID18 beamlines.
Progress beyond the state of the art:
At the start of ELASTIC, the project was entirely beyond state of the art. The diffraction resolution required to individuate the transformation had hardly been reached (and required further developments at the beamline for its resolution – which remains the only beamline capable of such measurements). The ultrasonic equipment was upgraded following Thomson et al., 2019 and had yet to be extended to smaller 7/3 assemblies capable of reaching the required pressures. This in turn required access to specialised Japanese anvils with increased hardness. With the combination, we were able to entertain world-beating records for the highest pressure-temperature ultrasound measurements. The data collection, in its ensemble, will not be bettered without a very significant change to the experiment at its most fundamental levels (new detector, anvils, ….).
Expected results until the end of the project:
At this time, our primary focus is to prepare manuscripts with the intention of achieving publication in open-access journals with high impact factors. Our goal is to submit one manuscript within four months, another within 10 months, and another within 16 months. Upon completion of the project, the results will be disseminated to the general public via the ESRF News and Highlights websites and Twitter feeds.
The recently opened upgrade of the synchrotron Moessbauer beamline at ID14 enables the analysis of Fe3+ in mineral phases with a spatial resolution of approximately 1 μm and greater precision. We intend to utilise this new opportunity through the submission of an application for beam time at ID14 in the next ESRF application round.
Potential impacts:
A comprehensive understanding of the seismic properties of the Earth's mantle (volatile-bearing) minerals, including their volatility, is essential for the resolution of precise seismic signatures observed at the deep Earth level, for seismic information is the only (untainted) information we receive from the deep Earth.
This study provides the first direct quantification of the effects and correlations between minor amounts of Fe and Ti in Al- and H2O-bearing eclogitic stishovite on density, elastic properties, and the post-stishovite transition over geologically relevant pressure-temperature conditions. This contributes to the behaviour of these materials as part of the subducting slab, particularly in relation to volume and buoyancy changes (which depend on density), seismic discontinuities (on bulk seismic velocities) and heterogeneities (on chemistry) caused by recycled oceanic crust during subduction into the Earth's deep convecting mantle. Furthermore, any correlation between defect content can also provide insight into the mechanisms by which defects are incorporated.
At the start of ELASTIC, the project was entirely beyond state of the art. The diffraction resolution required to individuate the transformation had hardly been reached (and required further developments at the beamline for its resolution – which remains the only beamline capable of such measurements). The ultrasonic equipment was upgraded following Thomson et al., 2019 and had yet to be extended to smaller 7/3 assemblies capable of reaching the required pressures. This in turn required access to specialised Japanese anvils with increased hardness. With the combination, we were able to entertain world-beating records for the highest pressure-temperature ultrasound measurements. The data collection, in its ensemble, will not be bettered without a very significant change to the experiment at its most fundamental levels (new detector, anvils, ….).
Expected results until the end of the project:
At this time, our primary focus is to prepare manuscripts with the intention of achieving publication in open-access journals with high impact factors. Our goal is to submit one manuscript within four months, another within 10 months, and another within 16 months. Upon completion of the project, the results will be disseminated to the general public via the ESRF News and Highlights websites and Twitter feeds.
The recently opened upgrade of the synchrotron Moessbauer beamline at ID14 enables the analysis of Fe3+ in mineral phases with a spatial resolution of approximately 1 μm and greater precision. We intend to utilise this new opportunity through the submission of an application for beam time at ID14 in the next ESRF application round.
Potential impacts:
A comprehensive understanding of the seismic properties of the Earth's mantle (volatile-bearing) minerals, including their volatility, is essential for the resolution of precise seismic signatures observed at the deep Earth level, for seismic information is the only (untainted) information we receive from the deep Earth.
This study provides the first direct quantification of the effects and correlations between minor amounts of Fe and Ti in Al- and H2O-bearing eclogitic stishovite on density, elastic properties, and the post-stishovite transition over geologically relevant pressure-temperature conditions. This contributes to the behaviour of these materials as part of the subducting slab, particularly in relation to volume and buoyancy changes (which depend on density), seismic discontinuities (on bulk seismic velocities) and heterogeneities (on chemistry) caused by recycled oceanic crust during subduction into the Earth's deep convecting mantle. Furthermore, any correlation between defect content can also provide insight into the mechanisms by which defects are incorporated.