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

• Main Authors: Bisnath, Avinash, Frimmel, H E, Armstrong, Richard, Board, W.S.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2015
• Subjects: Keywords: data set; dike; granite; granitoid; island arc; mafic rock; magmatic differentiation; magmatism; mesotrophic environment; metamorphism; orogeny; Proterozoic; recrystallization; SHRIMP dating; tectonophysics; uranium-lead dating; zircon; Antarctica; East A East Antarctica; Gjelsvikfjella; Gondwana; Maud Belt; Zircon geochronology; Antarctic; Dronning Maud Land; East Antarctica; Antarc*
• Online Access: http://hdl.handle.net/1885/27273

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 (1.2-1.0 Ga) and Neoproterozoic (0.6-0.5 Ga) 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 1140-1130 Ma volcanic arc. This was followed by 1104 ± 8 Ma 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 1070 Ma. 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 530 Ma. This was followed by late- to post-tectonic magmatism, reflected by 500 Ma granite bodies and 490 Ma aplite dykes as well as a 480 Ma gabbro body.