Granitoids from the Margate Terrane and their implications for tectono-magmatic models of the natal metamorphic province (South Africa)

R. J. Voordouw, H. M. Rajesh

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7 Citations (Scopus)

Abstract

Accepted models suggest that the c. 1.21 to 1.02 Ga Margate Terrane is one of three volcanic arc-like terranes that form the Natal Metamorphic Province in South Africa. Integration of new and compiled geological mapping and whole rock geochemical data, however, shows that ∼83% of bedrock exposure of the Margate Terrane is formed of ferroan to magnesian alkali-calcic granites that are more typical of petrogenesis within thick continental-like crust. Prominent negative Nb and Ti anomalies, as well as relatively low Sr., furthermore suggest petrogenesis above a subduction zone and/or derivation from juvenile volcanic arc-related rocks. Exposures of volcanic arc-like lithologies, on the other hand, comprise just ∼9% of all bedrock in the Margate Terrane and only ∼2% the granitoids. An alternative interpretation is therefore presented that suggests most of the "Margate Terrane" is in fact a ∼1.09 to 1.02 Ga granitic batholith.

Original languageEnglish
Pages (from-to)47-64
Number of pages18
JournalSouth African Journal of Geology
Volume115
Issue number1
DOIs
Publication statusPublished - Mar 1 2012

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terrane
island arc
petrogenesis
bedrock
geological mapping
batholith
rock
subduction zone
lithology
Africa
province
crust
anomaly
exposure

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

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abstract = "Accepted models suggest that the c. 1.21 to 1.02 Ga Margate Terrane is one of three volcanic arc-like terranes that form the Natal Metamorphic Province in South Africa. Integration of new and compiled geological mapping and whole rock geochemical data, however, shows that ∼83{\%} of bedrock exposure of the Margate Terrane is formed of ferroan to magnesian alkali-calcic granites that are more typical of petrogenesis within thick continental-like crust. Prominent negative Nb and Ti anomalies, as well as relatively low Sr., furthermore suggest petrogenesis above a subduction zone and/or derivation from juvenile volcanic arc-related rocks. Exposures of volcanic arc-like lithologies, on the other hand, comprise just ∼9{\%} of all bedrock in the Margate Terrane and only ∼2{\%} the granitoids. An alternative interpretation is therefore presented that suggests most of the {"}Margate Terrane{"} is in fact a ∼1.09 to 1.02 Ga granitic batholith.",
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AB - Accepted models suggest that the c. 1.21 to 1.02 Ga Margate Terrane is one of three volcanic arc-like terranes that form the Natal Metamorphic Province in South Africa. Integration of new and compiled geological mapping and whole rock geochemical data, however, shows that ∼83% of bedrock exposure of the Margate Terrane is formed of ferroan to magnesian alkali-calcic granites that are more typical of petrogenesis within thick continental-like crust. Prominent negative Nb and Ti anomalies, as well as relatively low Sr., furthermore suggest petrogenesis above a subduction zone and/or derivation from juvenile volcanic arc-related rocks. Exposures of volcanic arc-like lithologies, on the other hand, comprise just ∼9% of all bedrock in the Margate Terrane and only ∼2% the granitoids. An alternative interpretation is therefore presented that suggests most of the "Margate Terrane" is in fact a ∼1.09 to 1.02 Ga granitic batholith.

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