Kimberlite: Rapid Ascent of Lithospherically Modified Carbonatitic Melts

Russell, James K.; Porritt, L. A.; Hilchie, Luke

doi:10.1007/978-81-322-1170-9_12

Cited by 5 publications

(8 citation statements)

References 90 publications

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“…3; cf. Roedder, 1984;Smith and Evans, 1984). In these samples, the population density of sealed cracks is substantially less than for healed cracks (Fig.…”

Section: Mineral-and Fluid-filled Fracturesmentioning

confidence: 93%

“…Roedder, 1984;Smith and Evans, 1984). Typical examples of the intense networks of healed cracks within olivine from the Diavik and Igwisi Hills kimberlites are shown in the insets to Figs.…”

Section: Healed Cracksmentioning

confidence: 97%

“…The xenoliths are disaggregated releasing large populations of euhedral to subhedral olivine xenocrysts and other peridotitic minerals. All peridotitic minerals released to the magma are out of equilibrium and react and dissolve in the strongly silica-undersaturated melt at rates depending on their composition (e.g., Luth, 2009;Brett et al, 2009;Russell et al, 2012Russell et al, , 2013. Chemical dissolution produces the irregular, embayed, anhedral shapes found preserved as cores to xenocrystic and phenocrystic olivines (cf.…”

Section: First Order Interpretation Of Timing Relationshipsmentioning

confidence: 99%

“…This provides a continuous decrease in density, an increase in buoyancy and an accelerating ascent even with increasing loads of dense mantle cargo. Despite these recent advances in our understanding of kimberlite origins and transport (Wilson and Head, 2007;Sparks et al, 2006;Kavanagh and Sparks, 2009;Russell et al, 2012Russell et al, , 2013, many physical aspects of kimberlite ascent, and their time scales, remain unresolved.…”

Section: Introductionmentioning

confidence: 97%

“…These observations, combined with modelling of the decompression-driven, tensile failure of xenoliths and olivine crystals, lead to an integrated model for the physical transport of kimberlite magmas. We propose that ascent via upward dyke propagation through cratonic mantle lithosphere operates as a kimberlite factory, whereby parental carbonatitic magmas are progressively converted to kimberlite (e.g., Russell et al, 2012Russell et al, , 2013Bussweiler et al, 2015). The sequence of textural elements recorded by kimberlite-hosted olivine inform directly on the physical mechanisms, chemical conditions, and timescales of kimberlite ascent.…”

Section: Introductionmentioning

confidence: 99%

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The ascent of kimberlite: Insights from olivine

Brett

Russell

Andrews

et al. 2015

Earth and Planetary Science Letters

106

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Available online xxxx Editor: J. Brodholt Keywords: kimberlite olivine ascent decompression cracks carbonatite turbulent flowOlivine xenocrysts are ubiquitous in kimberlite deposits worldwide and derive from the disaggregation of mantle-derived peridotitic xenoliths. Here, we provide descriptions of textural features in xenocrystic olivine from kimberlite deposits at the Diavik Diamond Mine, Canada and at Igwisi Hills volcano, Tanzania. We establish a relative sequence of textural events recorded by olivine during magma ascent through the cratonic mantle lithosphere, including: xenolith disaggregation, decompression fracturing expressed as mineral-and fluid-inclusion-rich sealed and healed cracks, grain size and shape modification by chemical dissolution and abrasion, late-stage crystallization of overgrowths on olivine xenocrysts, and lastly, mechanical milling and rounding of the olivine cargo prior to emplacement. Ascent through the lithosphere operates as a "kimberlite factory" wherein progressive upward dyke propagation of the initial carbonatitic melt fractures the overlying mantle to entrain and disaggregate mantle xenoliths. Preferential assimilation of orthopyroxene (Opx) xenocrysts by the silica-undersaturated carbonatitic melt leads to deep-seated exsolution of CO 2 -rich fluid generating buoyancy and supporting rapid ascent. Concomitant dissolution of olivine produces irregular-shaped relict grains preserved as cores to most kimberlitic olivine. Multiple generations of decompression cracks in olivine provide evidence for a progression in ambient fluid compositions (e.g., from carbonatitic to silicic) during ascent. Numerical modelling predicts tensile failure of xenoliths (disaggregation) and olivine (cracks) over ascent distances of 2-7 km and 15-25 km, respectively, at velocities of 0.1 to >4 m s −1 . Efficient assimilation of Opx during ascent results in a silica-enriched, olivine-saturated kimberlitic melt (i.e. SiO 2 >20 wt.%) that crystallizes overgrowths on partially digested and abraded olivine xenocrysts. Olivine saturation is constrained to occur at pressures <1 GPa; an absence of decompression cracks within olivine overgrowths suggests depths <25 km. Late stage (<25 km) resurfacing and reshaping of olivine by particle-particle milling is indicative of turbulent flow conditions within a fully fluidized, gas-charged, crystal-rich magma.

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“…3; cf. Roedder, 1984;Smith and Evans, 1984). In these samples, the population density of sealed cracks is substantially less than for healed cracks (Fig.…”

Section: Mineral-and Fluid-filled Fracturesmentioning

confidence: 93%

Section: Healed Cracksmentioning

confidence: 97%

Section: First Order Interpretation Of Timing Relationshipsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The ascent of kimberlite: Insights from olivine

Brett

Russell

Andrews

et al. 2015

Earth and Planetary Science Letters

106

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Kimberlites: The deepest geochemical probes of Earth

Giuliani,

Dalton,

Pearson

2024

Reference Module in Earth Systems and Environmental Sciences

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H 2 O–CO 2 solubility in low SiO 2 -melts and the unique mode of kimberlite degassing and emplacement

Moussallam

Morizet

Gaillard

2016

Earth and Planetary Science Letters

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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. H2O-CO2 solubility in low SiO2-melts and the unique mode of kimberlite degassing and emplacement

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Kimberlite: Rapid Ascent of Lithospherically Modified Carbonatitic Melts

Cited by 5 publications

References 90 publications

The ascent of kimberlite: Insights from olivine

The ascent of kimberlite: Insights from olivine

Kimberlites: The deepest geochemical probes of Earth

H 2 O–CO 2 solubility in low SiO 2 -melts and the unique mode of kimberlite degassing and emplacement

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