Correlative tomography for polymineralic inclusion composition in sublithospheric diamonds

B. D.  Rayner; S. C.  Kohn; R. J. Garwood; A. D.  Burnham; G. P.  Bulanova; C. B.  Smith; A. R.  Thomson

doi:10.1029/2025GL114704

Correlative tomography for polymineralic inclusion composition in sublithospheric diamonds

B. D. Rayner, S. C. Kohn, R. J. Garwood, A. D. Burnham, G. P. Bulanova, C. B. Smith, A. R. Thomson

Earth and Environmental Sciences - Academic & Research

Research output: Contribution to journal › Article › peer-review

Abstract

Sublithospheric diamonds and their inclusions are the deepest known samples from the Earth’s mantle. Typically, the inclusions are trapped as minerals which are only stable in the deep mantle, retrogressing into multiple phases during their uplift. Determining the bulk inclusion composition is difficult but crucially important. Here we use micron-scale synchrotron X-ray computed tomography alongside μ-Raman mapping to reconstruct primary inclusion compositions using the example of seven former Ti-rich CaSi-perovskite inclusions, which had retrogressed to assemblages of breyite and CaTi-perovskite. The inclusions display Ti#s (molar Ti/[Ti+Si]), ranging from 0.02 to 0.60. In diamonds with previously-reported coexisting inclusions, former bridgmanite coexists with lower Ti# CaSi-perovskite and garnet inclusions with higher Ti# CaSi-perovskite. This observation is consistent with published petrological experiments on mafic compositions suggesting that CaSi-perovskite undergoes a reduction in Ti# after the post-garnet transition. Thus variations in Ti content of CaSi-perovskite inclusions are interpreted as differences in formation pressures.

Original language	English
Article number	e2025GL114704
Journal	Geophysical Research Letters
Volume	52
Issue number	11
Early online date	8 Jun 2025
DOIs	https://doi.org/10.1029/2025GL114704
Publication status	Published - 8 Jun 2025

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10.1029/2025GL114704Licence: CC BY

ICAL: Interdisciplinary Centre for Ancient Life
Garwood, R. (PI), Wogelius, R. (PI), Sansom, R. (PI), Buckley, M. (PI), Chamberlain, A. (CoI), Manning, P. (PI), Egerton, V. (CoI), Sellers, W. (PI), Nudds, J. (CoI), Bulot, L. G. (CoI), Brocklehurst, R. (PGR student), Brassey, C. A. (PI), Keating, J. (CoI), La Porta, A. (CoI), Brocklehurst, R. (PGR student), Callender-Crowe, L. (PGR student), Wallace, E. (PGR student), Chester, J. (PGR student), Davenport, J. (PGR student), Tuley, K. (PGR student), Lomax, D. (Researcher), Reeves, J. (PGR student), Smart, C. (PGR student), Ferro, C. (PGR student), Karoullas, C. (PGR student), Heath, J. (PGR student), Dickson, A. (PGR student), Austin Sydes, L. (PGR student), McLean, C. (PGR student), Harvey, V. (PGR student), Jones, K. (PI), Peacock, C. (PGR student), Gordon, P. (PGR student), Oldfield, E.-M. (PGR student), Webb, E. (PGR student), Roberts, F. (PGR student), Savage, H. (PGR student), Chester, J. (PGR student), Jepson, J. (Researcher), Keating, J. (Researcher) & Schwab, J. (Researcher)
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@article{86059abdf3b648188ab953a451a9334b,

title = "Correlative tomography for polymineralic inclusion composition in sublithospheric diamonds",

abstract = "Sublithospheric diamonds and their inclusions are the deepest known samples from the Earth{\textquoteright}s mantle. Typically, the inclusions are trapped as minerals which are only stable in the deep mantle, retrogressing into multiple phases during their uplift. Determining the bulk inclusion composition is difficult but crucially important. Here we use micron-scale synchrotron X-ray computed tomography alongside μ-Raman mapping to reconstruct primary inclusion compositions using the example of seven former Ti-rich CaSi-perovskite inclusions, which had retrogressed to assemblages of breyite and CaTi-perovskite. The inclusions display Ti\#s (molar Ti/[Ti+Si]), ranging from 0.02 to 0.60. In diamonds with previously-reported coexisting inclusions, former bridgmanite coexists with lower Ti\# CaSi-perovskite and garnet inclusions with higher Ti\# CaSi-perovskite. This observation is consistent with published petrological experiments on mafic compositions suggesting that CaSi-perovskite undergoes a reduction in Ti\# after the post-garnet transition. Thus variations in Ti content of CaSi-perovskite inclusions are interpreted as differences in formation pressures.",

author = "Rayner, \{B. D.\} and Kohn, \{S. C.\} and Garwood, \{R. J.\} and Burnham, \{A. D.\} and Bulanova, \{G. P.\} and Smith, \{C. B.\} and Thomson, \{A. R.\}",

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doi = "10.1029/2025GL114704",

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T1 - Correlative tomography for polymineralic inclusion composition in sublithospheric diamonds

AU - Rayner, B. D.

AU - Kohn, S. C.

AU - Garwood, R. J.

AU - Burnham, A. D.

AU - Bulanova, G. P.

AU - Smith, C. B.

AU - Thomson, A. R.

PY - 2025/6/8

Y1 - 2025/6/8

N2 - Sublithospheric diamonds and their inclusions are the deepest known samples from the Earth’s mantle. Typically, the inclusions are trapped as minerals which are only stable in the deep mantle, retrogressing into multiple phases during their uplift. Determining the bulk inclusion composition is difficult but crucially important. Here we use micron-scale synchrotron X-ray computed tomography alongside μ-Raman mapping to reconstruct primary inclusion compositions using the example of seven former Ti-rich CaSi-perovskite inclusions, which had retrogressed to assemblages of breyite and CaTi-perovskite. The inclusions display Ti#s (molar Ti/[Ti+Si]), ranging from 0.02 to 0.60. In diamonds with previously-reported coexisting inclusions, former bridgmanite coexists with lower Ti# CaSi-perovskite and garnet inclusions with higher Ti# CaSi-perovskite. This observation is consistent with published petrological experiments on mafic compositions suggesting that CaSi-perovskite undergoes a reduction in Ti# after the post-garnet transition. Thus variations in Ti content of CaSi-perovskite inclusions are interpreted as differences in formation pressures.

AB - Sublithospheric diamonds and their inclusions are the deepest known samples from the Earth’s mantle. Typically, the inclusions are trapped as minerals which are only stable in the deep mantle, retrogressing into multiple phases during their uplift. Determining the bulk inclusion composition is difficult but crucially important. Here we use micron-scale synchrotron X-ray computed tomography alongside μ-Raman mapping to reconstruct primary inclusion compositions using the example of seven former Ti-rich CaSi-perovskite inclusions, which had retrogressed to assemblages of breyite and CaTi-perovskite. The inclusions display Ti#s (molar Ti/[Ti+Si]), ranging from 0.02 to 0.60. In diamonds with previously-reported coexisting inclusions, former bridgmanite coexists with lower Ti# CaSi-perovskite and garnet inclusions with higher Ti# CaSi-perovskite. This observation is consistent with published petrological experiments on mafic compositions suggesting that CaSi-perovskite undergoes a reduction in Ti# after the post-garnet transition. Thus variations in Ti content of CaSi-perovskite inclusions are interpreted as differences in formation pressures.

U2 - 10.1029/2025GL114704

DO - 10.1029/2025GL114704

M3 - Article

SN - 0094-8276

VL - 52

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 11

M1 - e2025GL114704

ER -

Correlative tomography for polymineralic inclusion composition in sublithospheric diamonds

Abstract

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ICAL: Interdisciplinary Centre for Ancient Life

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