Dating basaltic volcanism in the Neoarchaean Sukumaland Greenstone Belt of the Tanzania Craton using the Sm-Nd method: implications for the geological evolution of the Tanzania Craton
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Date
2003
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Publisher
Elsevier
Abstract
Metabasalts from the Sukumaland Greenstone Belt of north western Tanzania yield a whole rock Sm–Nd isochron age of
2823 ± 44 Ma (initial ε(Nd) = 2.7, MSWD = 1.24). This age, which is interpreted as dating the eruption of the oldest mafic
volcanics in the belt, is at the 95% confidence level indistinguishable from 2780 ± 3 and 2808 ± 3Ma single zircon U–Pb
ages previously reported from stratigraphically higher rhyolitic pyroclastic rocks from the southern margin of the belt. The age
equivalency suggests that the entire∼5–7 km thick greenstone sequence that has been traditionally classified into a predominantly
mafic lower part overlain by an upper part in which felsic volcanics and BIF predominate, was emplaced within a relatively short
time interval not exceeding ∼44 Ma. The Sm–Nd age of the metabasalts is significantly older than a published zircon U–Pb
age of 2680 ± 3Ma obtained from a migmatitic gneiss on the southernmost fringe of the Sukumaland Greenstone Belt. This
corroborates previous evidence that high-grade metamorphism in the Tanzania Craton postdates emplacement of the greenstones
and is most likely associated with the regional emplacement of the large granitic bodies that intrude and flank the greenstones.
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Keywords
Tanzania Craton, Greenstone Belt, Metabasalts, Granitoids, Sm–Nd dating
Citation
Manya, S., Maboko, M.A.H., 2003. Dating basaltic volcanism in the Neoarchaean Sukumaland Greenstone Belt of the Tanzania Craton using the Sm-Nd method: implications for the geological evolution of the Tanzania Craton. Precambrian Research 121, 35 - 45.