Author
R.P. Hall
Bio: R.P. Hall is an academic researcher from University of Portsmouth. The author has contributed to research in topics: Mafic & Craton. The author has an hindex of 7, co-authored 7 publications receiving 360 citations.
Topics: Mafic, Craton, Mantle plume, Basalt, Magmatism
Papers
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TL;DR: Pb baddeleyite crystallization ages of ~1927 and ~1879 to ~1872 Ma for dolerite sills intruding the Waterberg Group in Botswana and South Africa were reported in this article.
Abstract: We report U–Pb baddeleyite crystallization ages of ~1927 and ~1879 to ~1872 Ma for dolerite sills intruding the Waterberg Group in Botswana and South Africa. These data increase the known extent of ~1.9 Ga intraplate magmatism in southern Africa and place tighter age constraints on the Waterberg Group than previously available. In South Africa, ~1.88 Ga dolerite intrudes upper Waterberg strata, constraining most, if not all, of the succession to have accumulated between ~2.06 Ga (age of the underlying Bushveld Complex) and ~1.88 Ga. This is consistent with derivation of much of the group from uplifted sources in reactivated segments of the Limpopo Belt. The dolerites are typical continental tholeiites, but their trace-element contents discriminate them from dolerite sills of the 1.1 Ga Umkondo Igneous Province, which occur in the same region. Paleomagnetic samples from dolerite intrusions in the Waterberg Group in South Africa (including one sill with a U–Pb baddeleyite age of ~1872 Ma), and from dolerite sills and basalt flows in the Soutpansberg Group to the east-northeast, yield antipodal directions with a site mean pole at 15.6°north, 17.1°east, A95 = 8.9°. These data are interpreted to indicate that the ~1879 to ~1872 Ma dolerites were intruded into the Waterberg Group during voluminous magmatism associated with development of the Soutpansberg rift basin. Older, ~1927 Ma dolerite in Botswana is similar in age and geochemistry to basalts in the craton-margin Olifantshoek Supergroup, suggesting that the mafic magmatism in those two regions is genetically related.
139 citations
TL;DR: The Kalahari Craton was initially stabilized following cessation of Palaeoproterozoic orogenesis in southern Africa at ca. 1.4-1.8 Ga as discussed by the authors.
110 citations
TL;DR: The greenstone belts of the western Superior Province are predominantly 2.78 to 2.69 Ga and provide evidence of oceanic and arc volcanism during the accretionary phase of development of the Superior Province as mentioned in this paper.
75 citations
TL;DR: The Mesoproterozoic Post-Waterberg sills A (MPWA sills) are characteristically LREE enriched with relatively unfractionated HREEs, and with normalised incompatible element profiles similar to modern island arc andesites as mentioned in this paper.
23 citations
TL;DR: One of the most significant mafic intrusive events in the Zimbabwe Craton was the emplacement of the Great Dyke layered ultramafic-mafic complex and its two parallel dykes at the end of the Archaean (∼2.6 Ga) as discussed by the authors.
18 citations
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TL;DR: Two geochemical proxies are particularly important for the identification and classification of oceanic basalts: the Th-Nb proxy for crustal input and hence for demonstrating an oceanic, non-subduction setting; and the Ti-Yb proxy, for melting depth and hence indicating mantle temperature and thickness of the conductive lithosphere as mentioned in this paper.
2,487 citations
TL;DR: In this paper, the authors proposed a model for the near-coeval formation of the Archaean continental crust (dominantly tonalite-trondhjemite-granodiorite: TTG), which can be explained by melting the base of basaltic plateaux formed above mantle upwellings (plumes), leaving behind restites containing pyroxene, garnet, and rutile.
658 citations
TL;DR: In this article, a full-plate, topological model of the Neoproterozoic that maps the evolution of the tectonic plate configurations during this time is presented.
473 citations
TL;DR: In this paper, the authors review the record of large igneous provinces (LIPs) emplaced during the 1600-700-Ma interval and identify such spatially separated but coeval LIPs at 1460, 1380, 1270, and 1115-1070-Ma.
435 citations
TL;DR: In this paper, a large number of geochemical and geophysical observations can be explained with episodic models for continental growth, which have in common episodic collapse of subducted slabs through the 660 km seismic discontinuity, mantle convection changing from layered to whole mantle, and each collapse correlates with major episodes of crustal formation.
388 citations