Geochemistry and petrogenesis of early Proterozoic intracratonic volcanic rocks of the Ventersdorp Supergroup, South Africa

Schweitzer, J. K.; Kröner, Alfred

doi:10.1016/0009-2541(85)90137-8

Cited by 31 publications

(11 citation statements)

References 32 publications

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“…Some of the analyzed samples in the present study have Loss on Ignition (LOI) values higher than expected ( Table 2). The data were, therefore, plotted in the CaO/Al 2 O 3 -MgO-SiO 2 diagram, proposed by Schweitzer and Kröner (1985) to test alteration effects in metavolcanic rocks. As seen, majority of the samples plot in the field of "unaltered rocks" except few samples with highest LOI (VA-R 223 and VA-R 127), which also show lowest (0.35 wt.%) and highest CaO (6.39 wt.%) contents respectively ( Fig.…”

Section: Geochemical Resultsmentioning

confidence: 99%

Neoproterozoic subduction-related metavolcanic and metasedimentary rocks from the Rey Bouba Greenstone Belt of north-central Cameroon in the Central African Fold Belt: New insights into a continental arc geodynamic setting

Bouyo

Zhao

Pénaye

et al. 2015

Precambrian Research

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Section: Geochemical Resultsmentioning

confidence: 99%

Neoproterozoic subduction-related metavolcanic and metasedimentary rocks from the Rey Bouba Greenstone Belt of north-central Cameroon in the Central African Fold Belt: New insights into a continental arc geodynamic setting

Bouyo

Zhao

Pénaye

et al. 2015

Precambrian Research

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“…Derivation of the Kaapvaal volcanics from the relatively Ti-and Fe-depleted subcontinental lithosphere could explain the relatively low Ti (Fig. 5e) and the consequent calcalkaline affinities of these rocks (Armstrong 1980;Sharpe et al 1983;Schweitzer & Kr6ner 1985).…”

Section: Discussionmentioning

confidence: 99%

Fundamental Uniformity in the Trace Element Patterns of the Volcanics of the Kaapvaal Craton from 3000 to 2100 Ma: Evidence for the Lithospheric Origin of These Continental Tholeiites

Myers¹,

Cawthorn²,

McCarthy³

et al. 1987

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In order to examine the nature of the mantle beneath the Kaapvaal Craton in southern Africa, data from thirteen volcanic sequences ranging in age from 3000 to 2100 Ma have been examined in this study. Variations in Nb, La, Ce, P, Zr, Ti, and Y have been evaluated using a niobium-normalized spidergram which minimizes variations due to fractional crystallization and clearly illustrates mantle source variations. Using this diagram a pattern, showing strong LREE enrichment of source relatively depleted in niobium and titanium, has been identified which remains quantitatively the same throughout this time period, indicating that it is the result of a reproducible equilibrium process. Melting of an incompatible element enriched (modally metasomatized) subcontinental lithosphere in which renewable metasomatic phases, such as diopside, are residual during melting can explain the quantitative uniformity and the time independence of this pattern.

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“…We have tried to specify the tectonic setting of the former basalts by using discrimination diagrams. Results obtained by this method are problematic, because several studies have shown that discrimination diagrams often fail to unambiguously classify tectonic settings (Wood et al 1979;Holm 1982;Schweitzer and Kröner 1985;Duncan 1987). Furthermore, the primary basaltic compositions may have changed due to postmagmatic alteration processes or the Cadomian MP metamorphism, which locally reached granulite facies conditions.…”

Section: Discussionmentioning

confidence: 99%

Ocean floor basalt, not continental gabbro: a reinterpretation of the Hoher Bogen amphibolites, Teplá-Barrandian, Bohemian massif

Propach¹,

Pfeiffer²

1998

Geologische Rundschau

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At its southern margin along the Hoher Bogen mountain, the Teplá-Barrandian (Bohemian massif, Central Europe) is made up of a 1-to 4-km wide belt of amphibolites. An upper amphibolite/lower granulite facies Variscan metamorphism has brought forth coarse-grained, weakly foliated rocks with hbl+pl±cpx±opx±grt parageneses. Since the beginning of this century, these rocks, together with fine-grained or mylonitized amphibolites, have been regarded as metamorphic gabbros (gabbro amphibolites) of the Neukirchen-Kdyne igneous complex. Relics of magmatic textures, however, cannot be found anywhere. The amphibolites are therefore reinterpreted as metamorphic basalts. The Hoher Bogen amphibolites (HBA) derive from N-type MORB. The most primitive samples have Mg#s between 60 and 65. Locally occurring (garnet-)hornblendites and leucodioritic mobilisates are the products of partial melting of amphibolites during the Variscan metamorphism and do not belong to the primary magmatic rock association. Ultramafic rocks are tectonically emplaced between the HBA belt and the metapelitic rocks of the Moldanubian. At the very least, the metapyroxenites among them seem to have a cumulus origin. Together with the ultramafic rocks, the HBA belt may be regarded as a metaophiolite, comparable to the Mariánské Lazne complex. The reinterpretation of the former "gabbro amphibolites" as a metaophiolite has consequences for the geology of the Teplá-Barrandian: the size of the Neukirchen-Kdyne igneous complex is reduced. The HBA belt is a piece of oceanic crust which is possibly younger than the Precambrian metasedimentary/metavolcanic country rock of the Neukirchen-Kdyne igneous complex.

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Geochemistry and petrogenesis of early Proterozoic intracratonic volcanic rocks of the Ventersdorp Supergroup, South Africa

Cited by 31 publications

References 32 publications

Neoproterozoic subduction-related metavolcanic and metasedimentary rocks from the Rey Bouba Greenstone Belt of north-central Cameroon in the Central African Fold Belt: New insights into a continental arc geodynamic setting

Neoproterozoic subduction-related metavolcanic and metasedimentary rocks from the Rey Bouba Greenstone Belt of north-central Cameroon in the Central African Fold Belt: New insights into a continental arc geodynamic setting

Fundamental Uniformity in the Trace Element Patterns of the Volcanics of the Kaapvaal Craton from 3000 to 2100 Ma: Evidence for the Lithospheric Origin of These Continental Tholeiites

Ocean floor basalt, not continental gabbro: a reinterpretation of the Hoher Bogen amphibolites, Teplá-Barrandian, Bohemian massif

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