Oroclinal Bending in the southern New England Orogen (eastern Australia): a geological field excursion from Brisbane to Sydney

Abstract

A series of tight bends are recognised in the southern New England Orogen in the area between Brisbane and Newcastle. This field excursion will provide an opportunity to become familiar with this spectacularly contorted orogen, to evaluate alternative geometrical interpretations, and to discuss possible tectonic models. The geometry of the New England oroclines is controversial, with alternative models suggesting a structure of 2, 3 or 4 oroclines. The tectonic setting responsible for these curvatures is largely unknown. During the four-day field excursion, we will explore the different tectonic elements that outline the oroclinal structure, including rocks that originated in a Devonian-Carboniferous convergent margin (subduction complex, forearc basin and volcanic arc) and a folded belt of early Palaeozoic serpentinites and high-pressure rocks. An emphasis will be given to exposures of early Permian rocks, predominantly S-type granitoids and rift-related sedimentary rocks, which most likely originated in a backarc setting during the early stages of oroclinal bending.