Stenian - Tonian and Ediacaran metamorphic imprints in the southern Paleoproterozoic Ubendian Belt, Tanzania: Constraints from in situ monazite ages

Abstract

In situ monazite geochronological data yield the timing of migmatitic metamorphism in southern Ubendian Belt. The mineral assemblage of garnet-biotite- sillimanite- K–feldspar- plagioclase-quartz- ilmenite, in migmatitic metapelitic gneisses was achieved during the Ediacaran metamorphic episode between 565 ± 4 Ma and 559 ± 8 Ma as manifested by dating of monazite grains that include garnet. The Ediacaran metamorphic event in the southern Ubendian Belt overprinted the Paleoproterozoic metamorphic event established at 1808 ± 9 Ma and the Mesoproterozoic metamorphic event at 944 ± 4 Ma (Tonian Period).The Stenian - Tonian and Ediacaran metamorphic imprints in the southern Ubendian Belt fall within the time window of metamorphism and deformation of the neighboring Irumide, southern Irumide, and Unango/Marrupa Complexes. The ca. 560 Ma old granulite facies imprinting in the southern Ubendian Belt is coeval with shear zone patterns in the neighboring Nyika Terrane in NE Malawi the event that was followed by eclogite facies metamorphism during the last stage of Gondwana amalgamation.