The MARID (mica-amphibole-rutile-ilmenite-diopside) suite of xenoliths in kimberlite

Dawson, J. B.; Smith, J. V.

doi:10.1016/0016-7037(77)90239-3

Cited by 295 publications

(111 citation statements)

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“…Compositions proposed include phlogopite-carbonate harzburgite 14,17 , phlogopite-diopside garnet-bearing peridotite 9,15 and peridotite with veins of phlogopite, K-richterite, apatite, carbonates and diopside 1 . It is noteworthy that the veined peridotite composition proposed by Mitchell 1 is very similar to that of the MARID (mica-amphibole-rutile-ilmenite-diopside) suite of mantle xenoliths 18 ; the only notable differences are the presence of Ti-phases and apparent absence of carbonates in MARID rocks.…”

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confidence: 57%

“…The two samples studied here exhibit coarse-grained foliated textures, with compositional banding related to the preferential concentrations of K-richterite and phlogopite in discrete layers (Fig. 3), a common feature of MARID rocks 18,19 . Clinopyroxene in textural equilibrium with phlogopite and K-richterite occurs in sample XM1/331, but is absent in sample BLFX-3-again this is not unusual for MARID samples 18 .…”

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confidence: 90%

“…MARID rocks have been transported from the lithospheric mantle to the Earth's surface by kimberlite, orangeite and lamprophyre magmas from various localities worldwide [18][19][20][21][22] . MARID rocks represent an extreme example of mantle metasomatism because of their exceptional enrichment in alkalis, LREE, HFSE (for example, Ti, Zr, Nb) and volatile species, primarily H 2 O (ref.…”

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confidence: 99%

“…The Kimberley area is unique because it hosts kimberlites (B81-95 Myr ago 16,[28][29][30] ) that were emplaced after the orangeites of the Barkly West-Boshof district (115-128 Myr ago 29,31 ; Fig. 2), and the Kimberley kimberlites host a variety of metasomatized mantle xenoliths, which have been extensively studied 11,12,18,19,[32][33][34][35][36][37] . Thus, mantle xenoliths entrained by the Bultfontein kimberlite can be considered representative of the same mantle lithosphere that produced the Barkly West-Boshof orangeites.…”

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confidence: 99%

“…2). MARID xenoliths are relatively common in the Kimberley kimberlites 12,18,19,35,39,40 . The two samples studied here exhibit coarse-grained foliated textures, with compositional banding related to the preferential concentrations of K-richterite and phlogopite in discrete layers (Fig.…”

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confidence: 99%

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Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

et al. 2015

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Kimberlites and orangeites (previously named Group-II kimberlites) are small-volume igneous rocks occurring in diatremes, sills and dykes. They are the main hosts for diamonds and are of scientific importance because they contain fragments of entrained mantle and crustal rocks, thus providing key information about the subcontinental lithosphere. Orangeites are ultrapotassic, H 2 O and CO 2 -rich rocks hosting minerals such as phlogopite, olivine, calcite and apatite. The major, trace element and isotopic compositions of orangeites resemble those of intensely metasomatized mantle of the type represented by MARID (mica-amphibolerutile-ilmenite-diopside) xenoliths. Here we report new data for two MARID xenoliths from the Bultfontein kimberlite (Kimberley, South Africa) and we show that MARID-veined mantle has mineralogical (carbonate-apatite) and geochemical (Sr-Nd-Hf-O isotopes) characteristics compatible with orangeite melt generation from a MARID-rich source. This interpretation is supported by U-Pb zircon ages in MARID xenoliths from the Kimberley kimberlites, which confirm MARID rock formation before orangeite magmatism in the area.

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confidence: 57%

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confidence: 90%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

et al. 2015

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Erosion patterns and mantle sources of topographic change across the southern African Plateau derived from the shallow and deep records of kimberlites

Stanley

Flowers

Bell

2015

Geochem Geophys Geosyst

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Flow in the sublithospheric mantle is increasingly invoked as a mechanism to explain both modern and past surface topography, but the importance of this phenomenon and its influence at different localities are debated. Southern Africa is an elevated continental shield proposed to represent dynamically supported topography. However, this region is also characterized by a complex lithospheric architecture variably affected by Cretaceous heating, thinning, and metasomatic alteration. We used apatite (U-Th)/He thermochronometry on 15 Cretaceous kimberlites from an 600 km long transect across the Kaapvaal Craton, combined with information from xenoliths in these pipes, to determine the plateau interior erosion history. The goal was to determine the relationships with lithospheric modification patterns and thereby better isolate the sublithospheric contribution to elevation. The results document a wave of erosion from west to east across the craton from 120 to <60 Ma, initially focused along paleorivers and then retreating as a scarp across the landscape. This spatially variable erosion event was associated with limited modification of the Archean cratonic lithospheric mantle as recorded by mantle xenoliths and xenocrysts, implying that dynamic buoyancy sources may be required to explain the elevations. In contrast, off-craton to the southwest, a more pronounced regional erosion phase at 110-90 Ma was coincident with significant modification of the Proterozoic lithospheric mantle. This relationship suggests that lithospheric processes were more important contributors to erosion and topographic change off-craton than on-craton. Together, these results suggest that lithospheric architecture can have an important control on the surface expression of mantle dynamics.

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Decarbonation in an intracratonic setting: Insight from petrological‐thermomechanical modeling

Gonzalez

Gorczyk

2017

JGR Solid Earth

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Cratons form the stable core roots of the continental crust. Despite long‐term stability, cratons have failed in the past. Cratonic destruction (e.g., North Atlantic Craton) due to chemical rejuvenation at the base of the lithosphere remains poorly constrained numerically. We use 2‐D petrological‐thermomechanical models to assess cratonic rifting characteristics and mantle CO2 degassing in the presence of a carbonated subcontinental lithospheric mantle (SCLM). We test two tectonothermal SCLM compositions: Archon (depleted) and Tecton (fertilized) using 2 CO2 wt % in the bulk composition to represent a metasomatized SCLM. We parameterize cratonic breakup via extensional duration (7–12 Ma; full breakup), tectonothermal age, TMoho (300–600°C), and crustal rheology. The two compositions with metasomatized SCLMs share similar rifting features and decarbonation trends during initial extension. However, we show long‐term (>67 Ma) stability differences due to lithospheric density contrasts between SCLM compositions. The Tecton model shows convective removal and thinning of the metasomatized SCLM during failed rifting. The Archon composition remained stable, highlighting the primary role for SCLM density even when metasomatized at its base. In the short‐term, three failed rifting characteristics emerge: failed rifting without decarbonation, failed rifting with decarbonation, and semifailed rifting with dry asthenospheric melting and decarbonation. Decarbonation trends were greatest in the failed rifts, reaching peak fluxes of 94 × 104 kg m−3. Increased TMoho did not alter the effects of rifting or decarbonation. Lastly, we show mantle regions where decarbonation, mantle melting in the presence of carbonate, and preservation of carbonated mantle occur during rifting.

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The MARID (mica-amphibole-rutile-ilmenite-diopside) suite of xenoliths in kimberlite

Cited by 295 publications

References 9 publications

Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

Did diamond-bearing orangeites originate from MARID-veined peridotites in the lithospheric mantle?

Erosion patterns and mantle sources of topographic change across the southern African Plateau derived from the shallow and deep records of kimberlites

Decarbonation in an intracratonic setting: Insight from petrological‐thermomechanical modeling

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