Geochronology, classification and mantle source characteristics of kimberlites and related rocks from the Rae Craton, Melville Peninsula, Nunavut, Canada

Sarkar, C. K.; Kjarsgaard, Bruce A.; Pearson, D. Graham; Heaman, Larry M.; Locock, Andrew J.; Armstrong, J.

doi:10.1007/s00710-018-0632-5

Cited by 14 publications

(4 citation statements)

References 47 publications

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“…Operating conditions included an accelerating voltage 15 kV, beam current 20 nA, beam diameter 2 μm, and count times on both peaks and backgrounds between 20 and 60 s. The calibrant materials used were a mixture of natural and synthetic minerals, including pure metals and oxides. Further details of these analyses can be found in Sarkar et al 54 .…”

Section: Methodsmentioning

confidence: 99%

Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites

Giuliani,

Phillips,

Pearson

et al. 2024

International Kimberlite Conference Extended Abstracts: 2024

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Section: Methodsmentioning

confidence: 99%

Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites

Giuliani,

Phillips,

Pearson

et al. 2024

International Kimberlite Conference Extended Abstracts: 2024

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“…However, studies by Mahotkin (1998) and O'Brien and Tyni (1999) described and classified rocks from Finland and western Russia as Gp II kimberlite, and also as olivine lamproite. Sarkar et al (2018) described and classified kimberlite pipes and orangeite sills, and kimberlite dikes and olivine lamproites from northern and southern Melville Peninsula (Arctic Canada), respectively; the olivine lamproites have similarities in mineralogy, bulk composition and age to the lamprophyric rocks of Sisimiut, Greenland studied by (Scott 1979(Scott , 1981 and Thy et al (1987). However, the Sisimiut rocks are better described as carbonate-bearing olivine lamproites, due to their calcite contents.…”

Section: Kjarsgaard Et Al a Review Of The Geology Of Global Diamond M...mentioning

confidence: 99%

“…40). The majority of known Cambrian lamproites occur in the newly discovered Aviat (CROL) and Qilalugaq-Naujaat clusters, northern Rae craton, Canada (Sarkar et al 2018). One other Cambrian lamproite is reported from Priestly Peak, Antarctica (Black and James 1983).…”

Section: Kjarsgaard Et Al a Review Of The Geology Of Global Diamond M...mentioning

confidence: 99%

A Review of the Geology of Global Diamond Mines and Deposits

Kjarsgaard

Wit

Heaman

et al. 2022

Reviews in Mineralogy and Geochemistry

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Kjarsgaard et al.A Review of the Geology of Global Diamond Mines and Deposits 3 Table 1. Mineralogy of kimberlite, carbonate-rich olivine lamproite (CROL), and olivine lamproite. Minerals present Kimberlite Carbonate-rich olivine lamproite (CROL) Olivine lamproite Megacryst suite (> 1 cm) Common to absent Absent, rare Absent, ?very rare? Cognate and antecryst minerals Olivine Common to absent Rare to absent Rare to absent Phlogopite Minor to absent Common to minor Common, minor, rare Spinel Common to rare (spinel cores) Minor to absent (spinel cores) Minor to absent (spinel cores) Diopside Absent Rare to absent Rare to absent (Minor) Phenocryst /Microphenocrysts (0.2-1.0 mm) Olivine phenocrysts Common Common Common Olivine microphenocrysts Common Minor to rare Minor to rare Phlogopite phenocrysts Minor, rare, absent Common Common Phlogopite microphenocrysts Minor, rare (poikilitic) Common Common (poikilitic) Spinel phenocrysts Common to minor Minor to rare Minor to rare Diopside microphenocrysts Absent Variable: Common to absent Minor to absent Groundmass (<0.2 mm) Olivine Common Minor to rare Rare, absent Phlogopite Common, laths (poikilitic) Common (poikilitic) Common (poikilitic) Spinel Common to minor Minor to rare Minor to rare Glass Absent, exceptionally rare? Absent (not reported) Common, minor, rare Apatite Common to rare Common to minor Minor to rare Perovskite Common to minor, rare Minor to rare Minor to rare Carbonate (calcite, dolomite) Common to minor Common to minor Rare, absent

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“…Third, the introduction of a carbonaterich lamproite subgroup obstructs the classification of ultramafic lamprophyres (Tappe et al 2005), because the carbonate-rich lamprophyre variety aillikite would, by the same logic that was applied to type orangeite, also belong to the newly proposed lamproite class. Recently, Sarkar et al (2018) referred to carbonate-rich potassic ultramafic rocks, akin to aillikite or orangeite, as lamproites, which highlights the need for a more coherent classification scheme that can satisfactorily accommodate the petrographical variability of mantle-derived volatile-rich igneous rocks (Mitchell and Tappe 2010).…”

Section: Orangeite V Lamproite Terminologymentioning

confidence: 99%

Evolution of ultrapotassic volcanism on the Kaapvaal craton: deepening the orangeite versus lamproite debate

Tappe

Shaikh

Wilson

et al. 2021

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Orangeites are a significant source of diamonds, yet ambiguity surrounds their status among groups of mantle-derived potassic rocks. This study reports mineralogical and geochemical data for a ca. 140 Ma orangeite dyke swarm that intersects the Bushveld Complex on the Kaapvaal craton in South Africa. The dykes comprise distinctive petrographic varieties that are linked principally by olivine fractionation, with the most evolved members containing minor amounts of primary carbonate, sanidine and andradite garnet in the groundmass. Although abundant groundmass phlogopite and clinopyroxene have compositions that are similar to those of cratonic lamproites, these phases show notable Ti-depletion, which we consider a hallmark feature of type orangeites from the Kaapvaal craton. Ti-depletion is also characteristic for the bulk rock compositions and is associated with strongly depleted Th-U-Nb-Ta contents at high Cs-Rb-Ba-K concentrations. The resultant high LILE/HFSE ratios of orangeites suggest that mantle source enrichment occurred by metasomatic processes in the proximity of ancient subduction zones.The Bushveld-intersecting orangeite dykes have strongly enriched Sr-Nd-Hf isotopic compositions (initial 87Sr/86Sr = 0.70701-0.70741; εNd = −10.6 to −5.8; εHf = −14.4 to −2.5), similar to those of other orangeites from across South Africa. Combined with the strong Ti-Nb-Ta depletion, this ubiquitous isotopic feature points to the involvement of ancient metasomatized mantle lithosphere in the origin of Kaapvaal craton orangeites, where K-rich metasomes imparted a ‘fossil’ subduction geochemical signature. Previous geochronology studies identified ancient K-enrichment events within the Kaapvaal cratonic mantle lithosphere, possibly associated with collisional tectonics during the 1.2-1.1 Ga Namaqua-Natal orogeny of the Rodinia supercontinent cycle. It therefore seems permissible that the cratonic mantle root was preconditioned for ultrapotassic magma production by tectonomagmatic events that occurred along convergent plate margins during the Proterozoic. However, reactivation of the K-rich metasomes had to await establishment of an extensional tectonic regime, such as that during the Mesozoic breakup of Gondwana, which was accompanied by widespread (1000 × 750 km) small-volume orangeite volcanism between 200 and 110 Ma.Although similarities exist between orangeites and lamproites, these and other potassic rocks are sufficiently distinct in their compositions such that different magma formation processes must be considered. In addition to new investigations of the geodynamic triggers of K-rich ultramafic magmatism, future research should more stringently evaluate the relative roles of redox effects and volatile components such as H2O-CO2-F in the petrogeneses of these potentially diamondiferous alkaline rocks.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5440652

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Geochronology, classification and mantle source characteristics of kimberlites and related rocks from the Rae Craton, Melville Peninsula, Nunavut, Canada

Cited by 14 publications

References 47 publications

Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites

Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites

A Review of the Geology of Global Diamond Mines and Deposits

Evolution of ultrapotassic volcanism on the Kaapvaal craton: deepening the orangeite versus lamproite debate

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