The ca. 1740–1710Ma Leichhardt Event: Inversion of a continental rift and revision of the tectonic evolution of the North Australian Craton

• Published in: Precambrian research Vol. 292; pp. 75 - 92
• Main Authors: Blaikie, T.N., Betts, P.G., Armit, R.J., Ailleres, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2017
• Subjects: Aeromagnetic; Basin inversion; Gravity; Leichhardt Event; Mount Isa Inlier; North Australian Craton; Mount Isa Inlier; Basin inversion; Leichhardt Event; North Australian Craton; Aeromagnetic; Gravity
• ISSN: 0301-9268; 1872-7433
• DOI: 10.1016/j.precamres.2017.02.003

•Uses geophysical interpretation of the Leichhardt River Fault Trough, Mount Isa Inlier.•We identify a major Proterozoic basin inversion event in the NE parts of the North Australian Craton, termed the Leichhardt Event.•The paper also discusses implications for paleogeography of Proterozoic Australia. Interpretation and modelling of high resolution regional geophysical data of the central Leichhardt River Fault Trough in the Mount Isa Inlier are used to determine the timing of a major basin inversion event following the development of the ca.1780–1740Ma Leichhardt Superbasin. Inversion of the Leichhardt Superbasin formed the regional north-south trending Leichhardt Anticline during east-west shortening. The limbs of the anticline are overprinted by several east-west trending wedge-shaped, non-magnetic sub-basins filled with ca.1710Ma Calvert and Isa superbasin successions. These relationships suggest inversion of the Leichhardt Superbasin occurred between ca.1740 and 1710Ma. The event is also known to have affected the northern and eastern North Australian Craton. The scale of the inversion suggests it was a significant event that we have defined as the Leichhardt Event. This event requires a major tectonic driver to the east of the North Australian Craton, possibly the accretion of a micro-continental ribbon to the east of the Mount Isa Inlier. The results of this study have implication for paleogeographic reconstruction of the Australian continent during the formation of Nuna because eastern North Australian Craton faced an ocean at ca.1740–1720Ma. The results also challenge the significance and intensity of crustal shortening associated with the ca.1600–1500Ma Isan Orogeny throughout the western Mount Isa Inlier.