Plate tectonic model for the Carboniferous evolution of the New England Fold Belt

Abstract

The New England Fold Belt forms the easternmost, youngest part of the Tasman Fold Belt System. For much of Late Palaeozoic time, it was a convergent plate margin at the edge of the Australian continent. At present, the New England Fold Belt is separated into the Yarrol Province in the north and the New England Province in the south by Mesozoic sediments of the Moreton‐Clarence Basin near the Queensland‐New South Wales border. In both provinces, parallel belts can be equated with volcanic arc, forearc basin and subduction complex assemblages, and clearly were originally continuous over the entire length of the fold belt. Formulation of a viable tectonic model for the Carboniferous history of the New England Fold Belt has been hampered by the following complicating factors: (1) all pre‐Permian tectonic elements of the Yarrol Province are displaced at least 200 km eastwards relative to their equivalents in the New England Province; (2) forearc basin and subduction complex assemblages are repeated across the northern part of the New England Province; (3) the Carboniferous subduction complex in the New England Province is folded into a large double orocline or megafold with a dextral sense of vergence and arcuate hinge zones near Texas in southern Queensland and Coffs Harbour in northeastern New South Wales; (4) continental margin arc volcanism was continuous in the New England Province throughout Carboniferous time, but appears to have ceased in the Yarrol Province in the mid‐Carboniferous. A plate tectonic model is presented which explains all four features by large‐scale dextral transform faulting of the eastern part of the New England Fold Belt in Middle and Late Carboniferous time. The model is based on the Late Cainozoic evolution of western North America and the formation of the San Andreas Fault.