Australian Governments over the past decade have acquired thousands of kilometres of high-quality deep-seismic reflection data. The deep-seismic reflection method is unique among imaging techniques in giving textural information as well as a cross sectional view of the overall crust, including the character of the middle crust, lower crust, Moho, and any upper mantle features. Seismic reflection data can be readily integrated with other geophysical and geological data to provide an unsurpassed understanding of a region's geological history as well as the mineral and energy resource potential. Continental Australia is made up of four main elements (blocks), separated by orogens. Most boundaries between the elements are deeply rooted in the lithosphere, and formed during amalgamation of Australia. Major boundaries within the elements attest to their individual amalgamation, mostly prior to the final construction of the continent. Many of Australia's mineral and energy resources are linked to these deep boundaries, with modern seismic reflection providing excellent images of the boundaries. All of the seismic surveys have provided new geological insights. These insights have significantly advanced the understanding of Australian tectonics. Examples include: preservation of extensional architecture in an otherwise highly shortened terrane (Arunta, Yilgarn, Mt Isa and Tanami), unknown deep structures associated with giant mineral deposits (Olympic Dam, Yilgarn, Gawler-Curnamona), as well as the discovery of unknown basins, sutures and possible subduction zones (Arunta, North Queensland, Gawler-Curnamona). These new insights provide not only an improved tectonic understanding, but also new concepts and target areas for mineral and energy resources.

The Onshore Energy Security Program was funded by the Australian Government from 2006 to 2011 to reduce risk in energy exploration. The program was delivered by Geoscience Australia, in collaboration with state and territory geological surveys, the National Research Facility for Earth Sounding (ANSIR) and AuScope. During this program approximately 6,500 line kilometres of deep crustal seismic reflection data were acquired and processed. The seismic images provide an understanding of the crustal architecture of sedimentary basins and their tectonic relationship to older basement terrains. Deep crust and upper mantle structures were also imaged and the Moho boundary could often be interpreted. The 2D seismic reflection data were acquired using three vibroseis trucks, with three 12 s variable frequency sweeps at each vibration point, usually with frequencies from 6 to 96 Hz. Correlated 20 s data were recorded, imaging to approximately 60 km depth. 300 geophone groups at 40 m intervals and 80 m source intervals provided 75 fold data. Data processing included imaging shallow sedimentary basins and also complex, deep, steeply dipping crystalline rock structures with high stacking velocities and out of plane energy. The seismic data, complemented by other geophysical and geological data, helped constrain and develop geological models. These models improved the understanding of crustal architecture in known hydrocarbon and metalliferous provinces as well as in frontier geological terrains.

<p>Geoscience Australia conducted the Bowen Basin Seismic Survey during July to October 1989. The major aim of the seismic survey was to record deep seismic reflection data across the northern part of the Bowen Basin, to test geological (extensional) models for the formation of the Bowen Basin. The deep seismic reflection survey by the BMR recorded 254 km of eight-fold Common-Depth-Point (CDP) seismic data, along three seismic lines.<p><b>Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 74954</b>

<p>Geoscience Australia conducted equipment tests at Millmerran, Queensland, using the newly acquired Sercel SN368 data acquisition seismic system. The equipment operated satisfactorily and proved to be versatile.<p><b>Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 74967</b>

Seismic reflection survey has been conducted to help identify the possible oil-bearing structures, which were revealed by two residual gravity anomalies in a geophysical survey made by the Bureau of Mineral Resources. Good reflections were obtained in some parts of the area, but the quality was not consistent. The seismic results appear to confirm a small closure near one of the gravity anomalies. No definite closure is shown near the other anomaly.

The Bureau of Mineral Resources made an experimental seismic survey in the Otway Basin, Victoria and SA, and in the Sydney Basin, NSW, from April to November 1965 and from mid February to mid March 1966. The survey used explosives as an energy source to obtain seismic reflection data for comparison with the results from an experimental 'Vibroseis' survey carried out for the Bureau by Seismograph Service Ltd during 1964.

A reconnaissance seismic reflection and refraction survey in the East Otway Basin, Victoria, was carried out by the Bereau of Mineral Resources from mid-February to mid-June 1967. The objective of the survey was to determine whether the gravity low areas of the Torquay Embayment and Port Phillip Sub-Basin in the eastern part of the Otway Basin contain thick Cretaceous sediments like those which has shown potential hydrocarbon source and reservoir characteristics in the western part of the Otway Basin. Nine reflection and five refraction traverses were recorded in the gravity low areas of the Barwon Trough and Port Phillip Sub-basin. Single-coverage reflection results of variable quality were obtained. Evidence for the presence of Tertiary section is provided by shallow reflections of good to fair quality, but the evidence for Cretaceous sediments is tenuous because of the poor quality of the deeper reflections, some of which may be multiples. The presence of several faults, onlappings and pinch-outs is also indicated. The refraction results are considered unreliable because of the difficulty of interpreting the discontinuous profiles and because of the mapped and suspected faults and pinch-outs in the sections.

A reconnaissance seismic survey was made in the area of Quilpie and Et.omanga in south-western Queensland. Traverses crossed the Harkaway, Pinkilla, and Tallyabra Domes. Reflection horizons were correlated with horizons within the Mesozoic sediments, and one persistent reflection was correlated with a horizon near the top of the Palaeozoic sediments. A thickness of sediments of up to 15,000 ft, including up to 11,000 ft of Palaeozoic rocks, was indicated on the flanks of the Harkaway and Pinkilla Domes. Results were compared with existing gravity data. Suggestions of faulting are based on seismic and gravity evidence taken together and also on gravity evidence alone in locations not covered by the seismic work.

On 30th March 1960, a seismic velocity survey was made in the A.A.O. Timbury Hills No. 2 bore, jointly by the Bureau of Mineral Resources and Associated Australian Oilfields N.L. The bore had been drilled to a depth of 4400 ft and was surveyed to a depth of 4304 ft below the rotary table. There remains a doubt whether the breaks recorded on the well geephone were, in fact, cable breaks, particularly between 2300 and 3305 ft below the rotary table. The interpretation has boon made with the belief that true breaks wore recorded. Average and interval velocities were computed and are acceptable geologically. Sandstones, particularly cemented ones, have Renerally higher velocities than shale. The average velocity of the Mesozoic sequence is about 9800 ft/sec. A velocity of 17,980 ft/sec was measured at the bottom of the bore and corresponds to the Timbury Hills Formation of unknown age. The Moolayember Shale has a low velocity calculated as 8360 ft/sec.

A seismic velocity survey of the APM Development Pty Limited No. 1 bore at Rosedale, Victoria, was made by the Geophysical Branch of the Bureau on the 3rd May 1960 using a TIC three-component well geophone. Measurements were taken with the geophone suspended in the well at selected intervals down to 5500 ft. It was apparent that signals reached the geophone by transmission along the cable by which it was suspended, and these interfered with the signals reaching the geophone along a path directly through the ground. This made interpretation difficult; however, by careful inspection of both the vertical and horizontal components of the signals received by the geophone at each depth, an interpretation has been made that yields a series of velocity/depth determinations. The average vertical velocity increases from 5000 ft/sec at the surface to 8930 ft/sec at a depth of 5500 ft. The average velocity in the Tertiary (0-2159 ft below datum) was computed to be 6420 ft/sec; the -werage velocity in the Mesozoic rocks penetrated (2159-5314 ft below datum) was 12,180 ft/sec. Two reflection spreads laid out and recorded in the vicinity of the bore showed the presence of reflectors at depths estimated to be in excess of 7700ft.