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, Eizou Nakamura

Research output: Contribution to journalArticle

22 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 languageEnglish
Pages (from-to)227-242
Number of pages16
JournalPrecambrian Research
Volume113
Issue number3-4
DOIs
Publication statusPublished - Jan 31 2002

Fingerprint

magmatism
shield
Rocks
crust
convergent margin
mountain
granulite
Fractionation
granulite facies
Crystallization
protolith
rock
continental crust
crystallization
Contamination
fractionation
mantle
Chemical analysis
dating
contamination

Keywords

  • Crust formation
  • Granulites
  • Mozambique Belt
  • Sm-Nd geochronology
  • Tanzania

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geology

Cite this

@article{0ad638bb830e43b09ea7565c7ddf18e3,
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 Eizou Nakamura",
year = "2002",
month = "1",
day = "31",
doi = "10.1016/S0301-9268(01)00213-3",
language = "English",
volume = "113",
pages = "227--242",
journal = "Precambrian Research",
issn = "0301-9268",
publisher = "Elsevier",
number = "3-4",

}

TY - JOUR

T1 - Isotopic dating of Neoproterozoic crustal growth in the Usambara Mountains of northeastern Tanzania

T2 - Evidence for coeval crust formation in the Mozambique Belt and the Arabian-Nubian Shield

AU - Maboko, M. A H

AU - Nakamura, Eizou

PY - 2002/1/31

Y1 - 2002/1/31

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

KW - Granulites

KW - Mozambique Belt

KW - Sm-Nd geochronology

KW - Tanzania

UR - http://www.scopus.com/inward/record.url?scp=0037204147&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037204147&partnerID=8YFLogxK

U2 - 10.1016/S0301-9268(01)00213-3

DO - 10.1016/S0301-9268(01)00213-3

M3 - Article

VL - 113

SP - 227

EP - 242

JO - Precambrian Research

JF - Precambrian Research

SN - 0301-9268

IS - 3-4

ER -