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Abstract
The paper presents new data on the internal structure of super-deep (sublithospheric) diamonds from Saõ-Luiz river placers (Brazil) and from alluvial placers of the northeastern Siberian platform (Yakutia). The sublithospheric origin of these diamonds is supported by the presence of mineral inclusions corresponding to associations of the transition zone and lower mantle. The features of morphology and internal structure have been studied by optical and scanning electron microscopy (SEM), cathodoluminescence topography (CL), and electron backscatter diffraction (EBSD) techniques. Diamonds typically have complicated growth histories displaying alternating episodes of growth, dissolution, and post-growth deformation and crushing processes. Most crystals have endured both plastic and brittle deformation during the growth history. Abundant deformation and resorption/growth features suggest a highly dynamic growth environment for super-deep diamonds. High temperatures expected in the transition zone and lower mantle could explain the plastic deformations of super-deep diamonds with low nitrogen content.
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Wenz MD, Jacobsen SD, Zhang D, Regier M, Bausch HJ, Dera PK, Rivers M, Eng P, Shirey SB, Pearson DG. Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1763-1768. [PMID: 31490168 PMCID: PMC6730627 DOI: 10.1107/s1600577519006854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/13/2019] [Indexed: 06/10/2023]
Abstract
Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.
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Affiliation(s)
- Michelle D. Wenz
- Department of Earth and Planetary Sciences, Northwestern University, Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Steven D. Jacobsen
- Department of Earth and Planetary Sciences, Northwestern University, Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Dongzhou Zhang
- Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, HI 96822, USA
| | - Margo Regier
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, USA
| | - Hannah J. Bausch
- Department of Earth and Planetary Sciences, Northwestern University, Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Przemyslaw K. Dera
- Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, HI 96822, USA
| | - Mark Rivers
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, IL 60637, USA
| | - Peter Eng
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, IL 60637, USA
| | - Steven B. Shirey
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC 20015, USA
| | - D. Graham Pearson
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, USA
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Weis C, Sternemann C, Cerantola V, Sahle CJ, Spiekermann G, Harder M, Forov Y, Kononov A, Sakrowski R, Yavaş H, Tolan M, Wilke M. Pressure driven spin transition in siderite and magnesiosiderite single crystals. Sci Rep 2017; 7:16526. [PMID: 29184152 PMCID: PMC5705641 DOI: 10.1038/s41598-017-16733-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/11/2017] [Indexed: 11/09/2022] Open
Abstract
Iron-bearing carbonates are candidate phases for carbon storage in the deep Earth and may play an important role for the Earth's carbon cycle. To elucidate the properties of carbonates at conditions of the deep Earth, we investigated the pressure driven magnetic high spin to low spin transition of synthetic siderite FeCO3 and magnesiosiderite (Mg0.74Fe0.26)CO3 single crystals for pressures up to 57 GPa using diamond anvil cells and x-ray Raman scattering spectroscopy to directly probe the iron 3d electron configuration. An extremely sharp transition for siderite single crystal occurs at a notably low pressure of 40.4 ± 0.1 GPa with a transition width of 0.7 GPa when using the very soft pressure medium helium. In contrast, we observe a broadening of the transition width to 4.4 GPa for siderite with a surprising additional shift of the transition pressure to 44.3 ± 0.4 GPa when argon is used as pressure medium. The difference is assigned to larger pressure gradients in case of argon. For magnesiosiderite loaded with argon, the transition occurs at 44.8 ± 0.8 GPa showing similar width as siderite. Hence, no compositional effect on the spin transition pressure is observed. The spectra measured within the spin crossover regime indicate coexistence of regions of pure high- and low-spin configuration within the single crystal.
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Affiliation(s)
- Christopher Weis
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany.
| | - Christian Sternemann
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany
| | - Valerio Cerantola
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, Grenoble, 38000, France
| | - Christoph J Sahle
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, Grenoble, 38000, France
| | - Georg Spiekermann
- Institute of Earth and Environmental Science, Universität Potsdam, Potsdam, 14476, Germany.,Deutsches Elektronen-Synchrotron DESY, Hamburg, 22607, Germany
| | - Manuel Harder
- Deutsches Elektronen-Synchrotron DESY, Hamburg, 22607, Germany
| | - Yury Forov
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany
| | - Alexander Kononov
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany
| | - Robin Sakrowski
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany
| | - Hasan Yavaş
- Deutsches Elektronen-Synchrotron DESY, Hamburg, 22607, Germany
| | - Metin Tolan
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, 44227, Germany
| | - Max Wilke
- Institute of Earth and Environmental Science, Universität Potsdam, Potsdam, 14476, Germany
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