Geology and geochronology of the Emu Creek Block (northern New South Wales, Australia) and implications for oroclinal bending in the New England Orogen

The southern part of the New England Orogen exhibits a series of remarkable orogenic bends (oroclines), which include the prominent Z-shaped Texas and Coffs Harbour oroclines. The oroclines are defined by the curvature of Devonian–Carboniferous forearc basin and accretionary complex rock units. However, for much of the interpreted length of the Texas Orocline, the forearc basin is mostly concealed by younger strata, and crops out only in the Emu Creek Block in the eastern limb of the orocline. The geology of the Emu Creek Block has hitherto been relatively poorly constrained and is addressed here by presenting new data, including a revised geological map, stratigraphic sections and new detrital zircon U–Pb ages. Rocks of the Emu Creek Block include shallow-marine and deltaic sedimentary successions, corresponding to the Emu Creek and Paddys Flat formations, respectively. New detrital zircon U–Pb data indicate that these formations were deposited during the late Carboniferous and that strata were derived from a magmatic source of Devonian to Carboniferous age. The sedimentary provenance and detrital zircon age distribution suggest that the sequence was deposited in a forearc basin setting. We propose that the Emu Creek and Paddys Flat formations are arc-distal, along-strike correlatives of the northern Tamworth Belt, which is part of the forearc basin in the western limb of the Texas Orocline. These results confirm the suggestion that Devonian–Carboniferous forearc basin rocks surround the Texas Orocline and have been subjected to oroclinal bending