Petrological discrimination among Precambrian dyke swarms: Eastern Kaapvaal craton (South Africa)

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dc.contributor.authorKlausen M.B.
dc.contributor.authorSoderlund U.
dc.contributor.authorOlsson J.R.
dc.contributor.authorErnst R.E.
dc.contributor.authorArmoogam M.
dc.contributor.authorMkhize S.W.
dc.contributor.authorPetzer G.
dc.date.accessioned2011-05-15T16:03:49Z
dc.date.available2011-05-15T16:03:49Z
dc.date.issued2010
dc.description.abstractAge-determinations on a complex array of mafic dykes across the eastern Kaapvaal craton (Olsson et al., 2010) are complemented herein by field evidence, dyke trend analysis, and petrological characterization of 58 dyke samples. ∼2.95. Ga SE-trending, a ∼2.65. Ga E- to SE-radiating, and ∼1.90. Ga NE-trending swarms can be distinguished. Prominent Archean (∼2.95 and ∼2.65. Ga) dyke ridges contain basement xenoliths, and have a more quartz-oversaturated, andesitic and calc-alkaline character. Proterozoic (∼1.90. Ga) dykes are, on the other hand, more aeromagnetically prominent tholeiitic basalts with higher modal (Fe, Ti)-oxide contents. Multi-elemental statistics indicate that the best geochemical discrimination is found between Archean high-Sr/V and La/Yb and Proterozoic low-Sr/V and La/Yb dyke swarms. The calc-alkaline character of Archean dyke swarms is augmented by LILE-enriched spider-element patterns with steeper REE-slopes as compared to the Proterozoic swarm. Geochemical similarities are roughly consistent with the ∼2.95 and ∼2.65. Ga dykes having fed coeval lavas within the Nsuze Group and Allanridge Formation (upper Ventersdorp Supergroup), respectively. ∼1.90. Ga dykes match coeval sills on both the Zimbabwe and Kaapvaal cratons, and are presumed feeders to Soutpansberg Group lavas. This new information provided by dated feeder dyke swarms leads to a re-evaluation of petrotectonic settings, ranging from continental back-arc to radiating swarms emanating from igneous (plume?) centers. © 2010.
dc.description.versionArticle
dc.identifier.citationPrecambrian Research
dc.identifier.citation183
dc.identifier.citation3
dc.identifier.issn3019268
dc.identifier.other10.1016/j.precamres.2010.01.013
dc.identifier.urihttp://hdl.handle.net/10019.1/12799
dc.subjectage determination
dc.subjectArchean
dc.subjectdike swarm
dc.subjectigneous geochemistry
dc.subjectpetrology
dc.subjectPrecambrian
dc.subjecttectonic setting
dc.subjecttholeiitic basalt
dc.subjectxenolith
dc.subjectKaapvaal Craton
dc.subjectZimbabwe Craton
dc.subjectAraneae
dc.titlePetrological discrimination among Precambrian dyke swarms: Eastern Kaapvaal craton (South Africa)
dc.typeArticle
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