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Single zircon ages for two Archean banded migmatitic gneisses from central Zimbabwe

Abstract:

We report new single zircon ages for two Archean banded gneisses from the Shangani Batholith in central Zimbabwe. The ages of ∼2.77 and ∼2.84 Ga do not support previous views that the area west of the current exposure of the Tokwe Segment was part of an early- to mid-Archean (>2.95 Ga) domain (Sebakwe Proto-craton). The data correspond to ∼2.9 to 2.8 Ga dates for TTG granitoids of the Chingezi Suite. Members of this suite occur as intrusions within the south-central part of the Zimbabwe Craton and are associated with contemporaneous felsic volcanic rocks. On the basis of their age distribution, isotopic characteristics and outcrop pattern with respect to the Tokwe Segment, the formation of these igneous rocks is consistent with the development of a volcanic arc along the western margin of the Sebakwe proto-craton between ∼2.9 to 2.8 Ga. © 2004 Geological Society of South Africa.