Cretaceous thermo-chemical modification of the Kaapvaal cratonic lithosphere, South Africa

Kobussen, A. F.; Griffin, William L.; O’Reilly, Suzanne Y.

doi:10.1016/j.lithos.2009.06.031

Cited by 48 publications

(43 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous work indicates that these different lithospheric domains were variably modified by a wave of Cretaceous lithospheric heating and metasomatism thought to originate from the same source but manifested differently depending on the lithospheric structure [ Bell et al ., ; Griffin , ; Kobussen et al ., ]. Importantly, these thermochemical changes can modify the lithospheric density structure, such that we might expect a different surface response in the off‐craton region where the lithospheric mantle was more strongly modified than on‐craton where the lithosphere was less‐affected by the same event.…”

Section: Discussionmentioning

confidence: 99%

“…How pervasive and permanent these modifications were is more ambiguous, because kimberlites only bring a limited sampling of the lithosphere to the surface and can locally alter their immediate mantle surroundings. However, it appears that these changes were more dramatic and infiltrated to shallower levels off‐craton and in areas of preexisting structures or weaknesses than on‐craton [ Bell et al ., ; Kobussen et al ., ; Griffin et al ., ]. Additionally, low heat flow measurements suggest that concentrations of U, Th, and K in the lithosphere must be low [ Rudnick et al ., ], suggesting relatively limited metasomatism within the craton.…”

Section: Coupling the Deep And Shallow Records Of Kimberlitesmentioning

confidence: 99%

“…Our initial study was in an off‐craton region of the plateau, and documented an interval of accelerated Cretaceous erosion contemporaneous with lithospheric heating, thinning, and metasomatism, suggesting that these lithospheric thermochemical changes contributed to surface uplift and erosion. This same mantle modification event, however, is less extensive and pervasive on‐craton [ Bell et al ., ; Griffin , ; Kobussen et al ., ]. Here we expand our previous work with an additional suite of 19 samples from 15 kimberlite pipes in an east‐west transect across the Kaapvaal craton to constrain the erosion histories and patterns across the southern African Plateau interior.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Coupling the Deep And Shallow Records Of Kimberlitesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

show abstract

“…Their modal compositions are listed in Table , as well as their in situ temperature estimates. Group I kimberlites of the Kaapvaal Craton and neighboring mobile belts erupted in the period 105–70 Ma [ Kobussen et al ., ]. Subsequent thermal relaxation since eruption will result in colder conditions than those indicated by the xenolith samples, and thermal arguments suggest a present‐day temperature of around 740°C beneath the Witwatersrand Basin in the center of the Kaapvaal Craton [ Jones , ].…”

Section: Inferences On the Correlation Between Seismic Velocity And Ementioning

confidence: 99%

Velocity‐conductivity relations for cratonic lithosphere and their application: Example of Southern Africa

Jones

Fishwick

Evans

et al. 2013

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[1] Seismic velocity is a function of bulk vibrational properties of the media, whereas electrical resistivity is most often a function of transport properties of an interconnected minor phase. In the absence of a minor conducting phase then the two should be inter-relatable primarily due to their sensitivity to temperature variation. We develop expressions between shear wave velocity and resistivity for varying temperature, composition, and water content based on knowledge from two kimberlite fields: Jagersfontein (Kaapvaal Craton) and Gibeon (Rehoboth Terrane). We test the expressions through comparison between a new high-resolution regional seismic model, derived from surface wave inversion of earthquake data from Africa and the surrounding regions, and a new electrical image from magnetotelluric (MT) data recorded in SAMTEX (Southern African Magnetotelluric Experiment). The data-defined robust linear regression between the two is found to be statistically identical to the laboratory-defined expression for 40 wt ppm water in olivine. Cluster analysis defines five clusters that are all geographically distinct and tectonically relate to (i) fast, cold, and variably wet Kaapvaal Craton, (ii) fast and wet central Botswana, (iii) slow, warm, and wet Rehoboth Terrane, (iv) moderately fast, cold, and very dry southernmost Angola Craton, and (v) slow, warm, and somewhat dry Damara Belt. From the linear regression expression and the MT image we obtain predicted seismic velocity at 100 km and compare it with that from seismic observations. The differences between the two demonstrate that the linear relationship between V s and resistivity is appropriate for over 80% of Southern Africa. Finally, using the regressions for varying water content, we infer water content in olivine across Southern Africa.

show abstract

“…This difficulty in reaching a clear consensus reflects the fact that mantlederived eclogites have resided in the SCLM, which has been intensively modified through time by metasomatic refertilisation processes (e.g. Griffin et al, 2003;Kobussen et al, 2009), implying that these eclogites also have experienced such metasomatic events (e.g. Sobolev et al, 1999b;Jacob et al, 2009;Smart et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Type I eclogites from Roberts Victor kimberlites: Products of extensive mantle metasomatism

Gréau

Huang

Griffin

et al. 2011

Geochimica et Cosmochimica Acta

Self Cite

View full text Add to dashboard Cite

Cretaceous thermo-chemical modification of the Kaapvaal cratonic lithosphere, South Africa

Cited by 48 publications

References 40 publications

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

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

Velocity‐conductivity relations for cratonic lithosphere and their application: Example of Southern Africa

Type I eclogites from Roberts Victor kimberlites: Products of extensive mantle metasomatism

Contact Info

Product

Resources

About