Petrogenesis of Group I Kimberlites from Kimberley, South Africa: Evidence from Bulk-rock Geochemistry

Roex, Anton P. le; Bell, David R.; Davis, Peter

doi:10.1093/petrology/egg077

Cited by 332 publications

(238 citation statements)

References 65 publications

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“…Plume impingement beneath the craton in the Cretaceous is thought to be responsible for kimberlite magmatism at that time (Le Roex et al, 2003;Becker and Le Roex, 2006). It may also have resulted in the deep intersection of the volatile-rich peridotite solidus and production of partial melts that have pervasively metasomatised and refertilised the deep mantle root, leading to "loss" of 40 km of the Kaapvaal root by asthenospherisation.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…However, unradiogenic Os retained in some of the deepest and hottest samples suggests that the root has not been completely replaced (Kobussen et al, 2008;Begg et al, 2009;O'Reilly and Griffin, 2010). The deep metasomatised root has warmed substantially (Bell et al, 2003) and become in parts almost indistinguishable from asthenospheric mantle. The thinner "LAB" corresponds to a depth where the amplitude of non-thermal seismic variations beneath the Kaapvaal craton is sharply reduced, which has been interpreted as the base of the chemical boundary layer (Artemieva, 2009).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

See 1 more Smart Citation

Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

Aulbach

Massuyeau

Gaillard

2017

Lithos

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

Aulbach

Massuyeau

Gaillard

2017

Lithos

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“…3D). The origin of the positive Pb anomaly in mafic rocks is more ambiguous because it can be generated either by crustal contamination, or by a secondary fluid circulation (e.g., Le Roex et al, 2003). Other anomalies, notably negative for K and Sr (except for sample LP 25) that are elements known to be highly mobile during alteration processes, will not be discussed any further.…”

Section: Volcanic Rocksmentioning

confidence: 99%

The volcaniclastic series from the Luang Prabang Basin, Laos: A witness of a triassic magmatic arc?

Rossignol

Bourquin

Poujol

et al. 2016

Journal of Asian Earth Sciences

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“…The chemical characteristic of this thick mantle lithosphere has been pivotal in buffering the tectonic and thermal history of southern Africa as a whole (Doucouré and de Wit, 2003a;Kaban et al, 2003;Micheat et al, 2007, and references therein). Nevertheless, episodically secondary (metasomatic) processes have significantly affected the chemistry, mineralogy, and density of the Kaapvaal cratonic lithosphere to varying degrees subsequent to its initial formation more than 3.2 Ga (de Wit et al, 1992;le Roex et al, 2003;Bell and Moore, 2004;Becker and le Roex, 2004;Harris et al, 2004;James et al, 2004;Shirey et al, 2005;Michaut et al, 2007). These have likely influenced at least second order epeirogenic features (Doucoure and de Wit, 2003a;Kaban et al, 2003).…”

Section: The Deep Lithosphere Of Cratonic Southern Africamentioning

confidence: 99%

“…Volatile induced metasomatism is ubiquitously associated with kimberlite magmatism (Wyllie, 1979;1987) and it has been recognized for several decades SOUTH AFRICAN JOURNAL OF GEOLOGY that metasomatism is geographically widespread beneath southern Africa (Gurney and Harte, 1980;Erlank et al, 1987;Gregoire et al, 2003;le Roex et al, 2003;Bell and Moore, 2004;Harris et al, 2004;Becker and le Roex, 2006). Such fluid activity has, therefore, also a long history within the mantle lithosphere of southern Africa, but particularly in the Mesozoic.…”

Section: Metasomatism In the Lithospheric Mantle Across Southern Africamentioning

confidence: 99%

The Kalahari Epeirogeny and climate change: differentiating cause and effect from core to space

Wit

2007

South African Journal of Geology

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Southern Africa's high Kalahari plateau and its flanking mountain ranges formed over an extended period of ~200 million years through vertical tectonic processes different from those at convergent plate boundaries. We refer to this as the Kalahari epeirogeny. Episodic uplift and erosion during the Kalahari epeirogeny is inferred from thermo-chronology and from stratigraphy of sediment accumulated around its continental margin. A total thickness of 2 to 7 km of rock (of which basalt was a major component) was eroded from the subcontinent's surface during two punctuated episodes of exhumation, in the early-Cretaceous and in the mid-Cretaceous. Major exhumation was over by the end of the Cretaceous, and the rate of erosion decreased by more than an order of magnitude to remove less than 1 km thickness of rock during the Cenozoic. Cosmogenic dating shows that erosion rates today are almost an order of magnitude less still.The cause for the Kalahari epeirogeny remains elusive, but three striking observations stand out: (i) major exhumation occurred during the late Mesozoic break-up of Gondwana; (ii) large scale basaltic magmatism closely match two accelerated episodes of exhumation: first along the west coast (~132 Ma, Etendeka large igneous province [LIP], associated with vast amounts of underplating along this entire passive margin), and the second flanking the sheared south coast margin (~90 Ma, Agulhas oceanic LIP). Yet exhumation that might have accompanied the vast Karoo LIP (~180 Ma) is not readily detected; (iii) the two main regional episodes of accelerated exhumation and coastal sediment accumulation are near synchronous with two regional 'spikes' of kimberlite intrusions: >450 kimberlites at ~90 Ma, and >200 kimberlites at ~120 Ma. Southern Africa is underlain by an anomalous warm region in the lowermost ~1500 km of the mantle that is linked to core to mantle heat loss. This warm region was inherited from a large Cretaceous thermo-chemical anomaly in the mantle created during long-lived subduction beneath Gondwana. Associated Mesozoic kimberlite genesis and basaltic magmatism may have been sufficient to cause volatile/heat-induced density changes in the lithospheric mantle of southern Africa to sustain the Kalahari plateau. In addition, such changes may have been induced by tectonic uplift and decompressional melting resulting from far-field collision processes between Africa and Europe, and/or final continental lithosphere decoupling between the Falkland plateau and southern Africa. CO 2 released into the ocean-atmosphere system during the Kalahari epeirogeny contributed to the global mid-Cretaceous hot-house conditions. However, because the CO 2 -consumption rate associated with basalt weathering is about eight times that of granite, atmospheric CO 2 was also efficiently sequestrated during the rapid erosion of Karoo basalt. Thus, the Kalahari epeirogeny also may have catalysed the onset of long-term global Cenozoic cooling.

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Petrogenesis of Group I Kimberlites from Kimberley, South Africa: Evidence from Bulk-rock Geochemistry

Cited by 332 publications

References 65 publications

Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

The volcaniclastic series from the Luang Prabang Basin, Laos: A witness of a triassic magmatic arc?

The Kalahari Epeirogeny and climate change: differentiating cause and effect from core to space

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