First evidence of hydrous silicic fluid films around solid inclusions in gem-quality diamonds

Nimis, Paolo; Alvaro, Matteo; Nestola, Fabrizio; Angel, R. J.; Marquardt, Katharina; Rustioni, Greta; Harris, Jeff W.; Marone, Federica

doi:10.1016/j.lithos.2016.05.019

Cited by 72 publications

(60 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A sixth inclusion, marked as Kyanite_6? in Figure , showed similar optical properties as the other kyanites, but its Raman signal was totally masked by a superimposed Raman spectrum similar to those reported by Nimis et al () and ascribed to the presence of a hydrous silicic fluid rim with Si (OH) 4 and Si 2 O(OH) 6 components (see Figure ). The same Raman features were observed around Kyanite_2, Kyanite_3, Kyanite_4, Kyanite_5, and the garnet inclusion.…”

Section: Resultssupporting

confidence: 82%

“…Typical Raman spectrum collected from kyanite and garnet inclusions in diamond JW9453_lot_23_Stone_1 showing the same broad peaks at 667 and 798 cm −1 found in Nimis et al () and indicating the presence of a hydrous silicic fluid containing Si (OH) 4 and Si 2 O(OH) 6 .…”

Section: Resultssupporting

confidence: 68%

“…The presence of a relatively compressible fluid film around the inclusion (cf. Nimis et al, ) or plastic deformation in the diamond might account for some pressure release, but their possible effects on the final P inc are still unknown (Angel et al, ). The proximity of this garnet to the external surface of the diamond, which would affect the P inc , cannot be invoked as the garnet was located deep within the diamond host.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of a relatively compressible fluid film around the inclusion (cf. Nimis et al, 2016) or plastic deformation in the diamond might account for some pressure release, but their possible effects on the final P inc are still unknown . The proximity of this Note.…”

Section: X-ray Diffractionmentioning

confidence: 99%

“…At present this can only be done by using a combination of computational and experimental methods (Anzolini et al, ). The presence of a fluid film surrounding the inclusion, as has recently been documented in several lithospheric diamonds (Nimis et al, ), may further complicate the modelling of the inclusion‐host system. The most important effect of a fluid rim could be to make the stress field close to hydrostatic.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Toward a Robust Elastic Geobarometry of Kyanite Inclusions in Eclogitic Diamonds

et al. 2018

View full text Add to dashboard Cite

Here we report the first results from elastic geobarometry applied to a kyanite inclusion entrapped within an eclogitic diamond (from Voorspoed mine, South Africa) using micro‐Raman and Fourier transform infrared spectroscopy, electron microprobe analysis, ab initio calculations, and finite element modeling. Application of elastic geobarometry to very elastically anisotropic kyanite inclusions is challenging, as current models do not allow for elastic anisotropy. In order to minimize the effects of anisotropy, we have explored the effects of deviatoric stress on Raman modes via ab initio density functional theory. The results allowed us to select the Raman mode (at ca. 638 cm−1) that is the least sensitive to deviatoric stress. The shift of this band in the inclusion while still trapped within the diamond relative to the inclusion in air (once liberated) was used under hydrostatic approximation to determine a residual pressure on the inclusion of 0.184 ± 0.045 GPa and an entrapment pressure of 5.2 ± 0.3 GPa (~160 km depth) for an FTIR N‐aggregation residence temperature of 1119 ± 50 °C. This is the first geothermobarometric determination for a diamond from the Voorspoed kimberlite. It overlaps with P–T estimates obtained by traditional chemical geobarometry for diamonds from other kimberlites from the Kaapvaal craton, suggesting that the hydrostatic approximation does not introduce significant errors in the geobarometric evaluation. Our protocol of Raman peak selection can be used for geobarometry of further kyanite‐bearing diamonds and may provide a guide for more robust geobarometry of other types of mineral inclusions in diamonds, both eclogitic and peridotitic.

show abstract

Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Section: X-ray Diffractionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations