REVIEW OF RECENT RESULTS FROM CONTINENTAL DEEP SEISMIC PROFILING IN AUSTRALIA

The Australian Geological Survey Organisation regularly collects 450-500 km of onshore deep seismic reflection data and up to 4500 km offshore each year in Australia. These recordings are made in a wide range of tectonic provinces, including, in the last few years, late Palaeozoic-Mesozoic intracontinental and Palaeozoic-Mesozoic-Cenozoic continental margin extensional basins, moderately deformed Palaeozoic transtensional basins and compressional fold belts, and Archaean greenstone terranes. Several of these provinces are major petroleum exploration provinces, whereas others contain significant mineral deposits. The primary purpose of the deep seismic profiling program is to resolve the tectonic history of the Australian continent, and thereby to encourage exploration for hydrocarbons and mineral resources in Australia. On the northwest Australian continental margin, major basin systems including the Bonaparte Basin, formed as a result of complex interactions since the Carboniferous, involving episodes of extension followed by strike-slip movements and inversion, which reactivated both the primary extensional and ancient basement structures. Off southeastern Australia, basins such as the Gippsland Basin formed as part of a linked transtensional system related to movement on a common mid-crustal detachment complex. On continental Australia, the Bowen Basin, in the northeast, was deformed by thrust faults that root in a major E-dipping detachment that flattens in the middle crust. The Cobar Basin, in the southeast, is a case where the seismic data support a detachment model in which the upper plate displacement vector can be calculated by plate reconstructions linking the geometry of the detachment surface with that of the basin. The greenstone terranes within the Eastern Goldfields region of Western Australia show crustal-scale fault systems that are planar and steep dipping, more in keeping with those interpreted in data from other Precambrian provinces rather than those of the Palaeozoic provinces.