Spence, Joshua S., Sanislav, Ioan V., and Dirks, Paul H.G.M. (2021) 1750–1710 Ma deformation along the eastern margin of the North Australia Craton. Precambrian Research, 353. 106019.

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Abstract

In this contribution, we present field-based evidence that in the Mary Kathleen Domain from the Eastern Fold Belt of the Mount Isa Inlier the 1790–1750 Ma metasediments of the Leichhardt Superbasin were sheared and folded between 1750 and 1710 Ma. The Mary Kathleen Domain consists of a series of anastomosing high and low strain domains intruded syn- to late-tectonically by a series of 1740–1710 Ma felsic and mafic plutons and dykes. The timing relationships in the high strain domains are unclear due to mylonitisation and transposition but in the lower strain domains are well-preserved. The earliest deformation, D1, consists of a series of low angle truncation surfaces and shear zones that are folded around large scale N-S trending upright folds during D2. The D2 folds were refolded during D3 along NW to EW trending fold axes. An undeformed granitic pluton from the Mt Godkin area dated at ~1710 Ma that crosscuts the D2-D3 folds and the youngest detrital zircon population of ~1750 Ma constrains the timing of D1-D3 deformation between 1750 and 1710 Ma. Later, N-S (D4) and N-E (D5) trending brittle-ductile shears are interpreted to indicate a late Isan Orogeny overprint. The occurrence of contemporaneous folding in the Western Fold Belt suggests that between 1750 and 1710 Ma the eastern margin of the North Australia Craton was experiencing a significant deformation event that can be correlated with similarly aged deformation events from other parts of the North Australia Craton, from South Australia Craton and from East Antarctica. Following the assembly of most of the Nuna Supercontinent by 1.8 Ga, we postulate that the 1750–1710 Ma deformation and plutonism observed in Mount Isa Inlier is part of a series of worldwide orogenic events that contributed to the final configuration of the Nuna Supercontinent.

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