Tectono-thermal evolution of the Maud Belt: New SHRIMP U–Pb zircon data from Gjelsvikfjella, Dronning Maud Land, East Antarctica

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The Maud Belt in Dronning Maud Land (western East Antarctic Craton) preserves a high-grade polyphase tectono-thermal history with two orogenic episodes of Mesoproterozoic (1.2–1.0Ga) and Neoproterozoic (0.6–0.5Ga) age. New SHRIMP U–Pb zircon data from southern Gjelsvikfjella in the northeastern part of the belt make it possible to differentiate between a series of magmatic and metamorphic events. The oldest event recorded is the formation of an extensive 1140–1130Ma volcanic arc. This was followed by 1104±8Ma granitoids that might represent, together with so far undated mafic dykes, part of a decompression melting-related bimodal suite that reflects the sub-continental Umkondo igneous event. The first high-grade metamorphism is constrained at 1070Ma. The metamorphic age data are similar to those obtained from other parts of the Maud Belt, but also from the Namaqua-Natal Belt in South Africa, but the preceding arc formation was diachronous in the two belts. This indicates that the two belts did not form a continuous volcanic arc unit as suggested in previous models, but became connected only at the end of the Mesoproterozoic.Intense reworking during the Neoproterozoic, probably as a result of continent–continent collision between components of Gondwana, is indicated by ductile refliation, further high-grade metamorphic recrystallisation and metamorphic zircon overgrowths at approximately 530Ma. This was followed by late- to post-tectonic magmatism, reflected by 500Ma granite bodies and 490Ma aplite dykes as well as a 480Ma gabbro body.