Isotopic dating of Neoproterozoic crustal growth in the Usambara Mountains of northeastern Tanzania: Evidence for coeval crust formation in the Mozambique Belt and the Arabian-Nubian Shield

M. A.H. Maboko; E. Nakamura

doi:10.1016/S0301-9268(01)00213-3

Isotopic dating of Neoproterozoic crustal growth in the Usambara Mountains of northeastern Tanzania: Evidence for coeval crust formation in the Mozambique Belt and the Arabian-Nubian Shield

M. A.H. Maboko, E. Nakamura

Research output: Contribution to journal › Article › peer-review

26 Citations (Scopus)

Abstract

Granulite-facies orthogneisses of andesitic to dacitic composition in the Usambara Mountains of north eastern Tanzania yield a Sm-Nd whole rock isochron age of 815 ± 58 Ma and an initial ε(Nd) value of 4.1. This age is interpreted as dating Sm-Nd fractionation during extraction from the mantle and immediate subsequent crystallisation of the granulite protolith during an event of regional calc-alkaline magmatism in the area. Isotopic and geochemical characteristics of the rocks are consistent with a convergent margin setting for the magmatism with minimal contamination by older continental crust. The isotopic data from the Usambara Mountains demonstrate that Neoproterozoic crust formation in the Arabian-Nubian Shield and parts of the Mozambique Belt was broadly contemporaneous.

Original language	English
Pages (from-to)	227-242
Number of pages	16
Journal	Precambrian Research
Volume	113
Issue number	3-4
DOIs	https://doi.org/10.1016/S0301-9268(01)00213-3
Publication status	Published - Jan 31 2002

Keywords

Crust formation
Granulites
Mozambique Belt
Sm-Nd geochronology
Tanzania

ASJC Scopus subject areas

Geology
Geochemistry and Petrology

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10.1016/S0301-9268(01)00213-3

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title = "Isotopic dating of Neoproterozoic crustal growth in the Usambara Mountains of northeastern Tanzania: Evidence for coeval crust formation in the Mozambique Belt and the Arabian-Nubian Shield",

abstract = "Granulite-facies orthogneisses of andesitic to dacitic composition in the Usambara Mountains of north eastern Tanzania yield a Sm-Nd whole rock isochron age of 815 ± 58 Ma and an initial ε(Nd) value of 4.1. This age is interpreted as dating Sm-Nd fractionation during extraction from the mantle and immediate subsequent crystallisation of the granulite protolith during an event of regional calc-alkaline magmatism in the area. Isotopic and geochemical characteristics of the rocks are consistent with a convergent margin setting for the magmatism with minimal contamination by older continental crust. The isotopic data from the Usambara Mountains demonstrate that Neoproterozoic crust formation in the Arabian-Nubian Shield and parts of the Mozambique Belt was broadly contemporaneous.",

keywords = "Crust formation, Granulites, Mozambique Belt, Sm-Nd geochronology, Tanzania",

author = "Maboko, {M. A.H.} and E. Nakamura",

note = "Funding Information: We acknowledge Chie Sakaguchi, Nobuko Takeuchi, Ryoji Tanaka, Hiroyuki Takei and Akio Makishima for technical assistance during different stages of the analytical work. The research was conducted while MAHM was a Visiting Research Scholar at the Institute for the Study of the Earths Interior, Okayama University at Misasa, Japan. Fieldwork was funded by a grant from the Tanzania Commission for Science and Technology. The paper has benefited from the critical reviews of A. Kroner, N. Harris, A. Moller, B. Mocek and R. Thomas.",

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AU - Nakamura, E.

N1 - Funding Information: We acknowledge Chie Sakaguchi, Nobuko Takeuchi, Ryoji Tanaka, Hiroyuki Takei and Akio Makishima for technical assistance during different stages of the analytical work. The research was conducted while MAHM was a Visiting Research Scholar at the Institute for the Study of the Earths Interior, Okayama University at Misasa, Japan. Fieldwork was funded by a grant from the Tanzania Commission for Science and Technology. The paper has benefited from the critical reviews of A. Kroner, N. Harris, A. Moller, B. Mocek and R. Thomas.

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N2 - Granulite-facies orthogneisses of andesitic to dacitic composition in the Usambara Mountains of north eastern Tanzania yield a Sm-Nd whole rock isochron age of 815 ± 58 Ma and an initial ε(Nd) value of 4.1. This age is interpreted as dating Sm-Nd fractionation during extraction from the mantle and immediate subsequent crystallisation of the granulite protolith during an event of regional calc-alkaline magmatism in the area. Isotopic and geochemical characteristics of the rocks are consistent with a convergent margin setting for the magmatism with minimal contamination by older continental crust. The isotopic data from the Usambara Mountains demonstrate that Neoproterozoic crust formation in the Arabian-Nubian Shield and parts of the Mozambique Belt was broadly contemporaneous.

AB - Granulite-facies orthogneisses of andesitic to dacitic composition in the Usambara Mountains of north eastern Tanzania yield a Sm-Nd whole rock isochron age of 815 ± 58 Ma and an initial ε(Nd) value of 4.1. This age is interpreted as dating Sm-Nd fractionation during extraction from the mantle and immediate subsequent crystallisation of the granulite protolith during an event of regional calc-alkaline magmatism in the area. Isotopic and geochemical characteristics of the rocks are consistent with a convergent margin setting for the magmatism with minimal contamination by older continental crust. The isotopic data from the Usambara Mountains demonstrate that Neoproterozoic crust formation in the Arabian-Nubian Shield and parts of the Mozambique Belt was broadly contemporaneous.

KW - Crust formation

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KW - Mozambique Belt

KW - Sm-Nd geochronology

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Isotopic dating of Neoproterozoic crustal growth in the Usambara Mountains of northeastern Tanzania: Evidence for coeval crust formation in the Mozambique Belt and the Arabian-Nubian Shield

Abstract

Keywords

ASJC Scopus subject areas

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