Zircon evaporation ages and chemical composition of a Migmatitic schist in the Obudu Plateau: Evidence for paleoproterozoic (ca.1789 Ma) component in the basement complex of southeastern Nigeria

Abstract:

Migmatitic biotite garnet schist in the Obudu Plateau of southeastern Nigeria is considered a metagrewacke, possibly derived from a granodioritic protolith. Its highest metamorphic imprint is up to upper amphibolite facies and also intrusion of granitic material appears to have contributed to migmatisation in the rock. The main metamorphic imprint recorded took place during the Pan-African orogeny at 605.3 ± 1.4Ma and 664.8 ± 1.5Ma ago. A zircon evaporation age of 1788.8 ± 2.1Ma in the rock is interpreted as the age of the granodioritic protolith or an earlier metamorphism and is the first evidence that the basement of southeastern Nigeria contains paleoproterozoic rocks. The age, when added to similar ones reported from parts of the Nigerian basement and neighbouring Cameroon, provides further evidence for a significant component of Paleoproterozoic crust in the southeastern part of the West African shield.

Año de publicación:

1998

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Fuente:

scopus