In 2008, as part of the Australian Government's Onshore Energy Security Program, Geoscience Australia, acquired deep seismic reflection, wide-angle refraction, magnetotelluric (MT) and gravity data along a 250 km east-west transect that crosses several tectonic domain boundaries in the Gawler Craton and also the western boundary of the South Australian Heat Flow Anomaly (SAHFA). Geophysical datasets provide information on the crustal architecture and evolution of this part of the Archean-Proterozoic Gawler Craton. The wide-angle refraction and MT surveys were designed to supplement deep seismic reflection data, with velocity information for the upper crust, and electrical conductivity distribution from surface to the upper mantle. The seismic image of the crust from reflection data shows variable reflectivity along the line. The upper 2 s of data imaged nonreflective crust; the middle to lower part of the crust is more reflective, with strong, east-dipping reflections in the central part of the section.The 2D velocity model derived from wide-angle data shows velocity variations in the upper crust and can be constrained down to a depth of 12 km. The model consists of three layers overlying basement. The mid-crustal basement interpreted from the reflection data, at 6 km in depth in the western part of the transect and shallowing to 1 km depth in the east, is consistent with the velocity model derived from wide-angle and gravity data. MT modelling shows a relatively resistive deep crust across most of the transect, with more conductive crust at the western end, and near the centre. The enhanced conductivity in the central part of the profile is associated with a zone of high reflectivity in the seismic image. Joined interpretation of seismic data supplemented by MT, gravity and geological data improve geological understanding of this region.

This report contains the results of a seismic survey on the Nerrima Dome, a major structure within the Fitzroy Basin and near its south-western boundary. The dome is situated near the Fitzroy River about 100 miles south-east of Derby in the West Kimberley district of Western Australia. The Nerrima Dome has been mapped at the surface in Permian sediments and is a complex structure. It was desired to determine if the dome existed at depth and, if not, the structure at depth, with a view to locating a site for a deep drilling test. The target beds for such a test are Devonian and/or Ordovician sediments over which the Permian sediments are believed to lie unconformably. Reflection methods were tried and proved unsuccessful and the survey was carried out using refraction methods. Although the structure underlying the dome has not been clearly shown, the refraction method has indicated that it is complex and does not conform with the domal structure at the surface. There appears to be a major unconformity at comparatively shallow depth (2000 ft). The deep structure (7000 ft) although apparently less complex than that immediately below the unconformity, also bears no obvious relation to structure at surface. The results so far obtained are reasonably conclusive in showing that no simple dome-like structure of large magnitude exists under the Nerrima Dome.

The seismic survey extending over the Poole Range and Price's Creek areas and the Pinnacle Fault, near the north-eastern boundary of the Fitzroy Basin. The survey was corducted during the winter of 1953. The Poole Range Dome has been mapped in outcropping rocks of Permian age, but its western closure is notcertain. It is at the south-eastern end of a line of anticlinal folding which includes the St. George Range Dome and Nerrima Dome. The target beds for an oil test bore would be the Devonian and/or Ordovician rocks, which crop out on tbe north-eastern side of the Pinracle Fault, ard over which the Permian rocks of the Poole Range are believed to lie unconformably. The seismic results indicate a thick section of sediments on the south-western side of the Pinnacle Fault and show a fair defree of conformity between shallow and deep reflections on the northern flank of the dome. Further investigation was made in 1954 around the flanks of the dome, to determine whether or not the domal structure persists at depth, but the interpretation of the results of the 1954 survey is not yet complete. The Ordovician roeks on tbe northeastern side of the Pinnacle fault are shown to have a probable unexposed thickness of about 900 feet.

The report describes work carried out during an ice thickness survey by seismic and gravimetric methods made in the summer of 1957-58 in MacRobertson Land, Antarctica. Methods used during the survey are described and the equipment used is listed in detail. Results have not yet been analysed fully but preliminary profiles are given. The accuracy limits applying to these profiles are given and future extensions of the calcu18tions are discussed.

At the request of West Australian Petroleum Pty. Ltd. and the Department of Mines, Western Australia, the Bureau carried out a seismic velocity survey in Rough Range No.1 Well, with the object of obtaining velocity distribution data for use in the interpretation of results of seismic refraction surveys in the area. Twenty-two shots were fired from a shot point about 1,000 feet from the well. Geophone depths in the welI ranged from 2,000 feet to 14,000 feet, usually at intervals of 500 feet, but the intervals were varied at points where there was a significant change in the stratigraphy. Recordings from 16 of the shots were used in the calculations. Results indicated that, as would be expected, the hard crystalline limestone which comprises the top 700 feet of section has a much higher velocity than the clastic limestones which underlie it. An abrupt velocity change from 7,100 ft/sec. to 12,600 ft/sec. at 3,250 feet corresponds approximately with the change from Windalia Radiolarite to Muderong shale, and also with a density change from 2.1 to 2.4. A second major velocity change from 12,600 ft/sec. to 16,500 ft/sec. at 6,800 feet also corresponds approximately with a density change from 2.5 to 2.7. An abnormal increase in velocity recorded at about 9,000 feet must be considered as very doubtful and velocities at this depth have been averaged.

Bureau of Mineral Resources conducted a seismic refraction survey during February 6th and March 5th, 1951. This survey aimed to resolve the shallow structure on the Comet anticlinal structure, 60 miles north of Rolleston for the oil exploration purpose.

At the request of the Australian Atomic Energy Commission, the Bureau of Mineral Resources, Geology & Geophysics conducted a seismic refraction survey on the site chosen for construction of a nuclear power station. The purpose of the survey was to determine the foundation conditions at the site and the properties of the rocks in relation to excavation methods and support of the proposed structures. The bedrock of the area consists of Permian sandstone (Jervis Bay Sandstone) overlain in places by unconsolidated Quaternary beach and dune sands. During the seismic work it was found that the sandstone beds have a relatively wide range of seismic velocities; often a higher-velocity bed overlies a lower-velocity bed, and this makes seismic refraction work difficult and less accurate. This is confirmed by laboratory measurements of seismic velocities on drill cores. Thin beds of higher- and lower-velocity sandstones occur, some too thin to be resolved by the seismic method. The seismic profiles presented must be considered bearing in mind these difficulties, Haterial sufficiently consolidated for foundations is shallow, and the seismic velocities indicate that some blasting will be necessary to excavate to the desired depth of 10 feet above mean high water level.

The term 'modelling while interpreting' refers to the use of 3D models during the interpretation of reflection seismic data in order to inform that process. Rather than using 3D models at a final stage of the project just to display results, new software tools are emerging to enable development of 3D models in parallel with the seismic interpretation work. These tools provide additional means to help interpreters make informed decisions such as where to pick basement and to check the 3D integrity of their geological models. Applications of this new workflow are illustrated through a recently completed petroleum prospectivity assessment of the Capel and Faust frontier deep-water basins located 800 km to the east of Brisbane. Geoscience Australia acquired 2D geophysical data across these basins in 2007 and subsequently mapped the complex distribution of sub-basins by integrating 2D time-domain seismic interpretation with 3D gravity modelling. Forward and inverse 3D gravity models were used to inform the seismic interpretation and test the seismic basement pick. The identification of basement was problematic due to a lack of wells and the likelihood that acoustic basement represented older sedimentary material intruded by igneous rocks. Sonobuoy refraction data were modelled to achieve conversion of travel times to depth and estimate densities. Modelling gravity while interpreting reflection seismic data improved confidence in the mapping of the extent and thickness of sediments in these basins, and has potential to be used more widely in mapping projects to reduce exploration risk.

At the request of the State Rivers and Water Supply Commission of Victoria, seismic tests using the refraction method were conducted over six well locations near Cobram in the Murray Valley Irrigation District of Central Northern Victoria. The purpose of the tests was to determine whether the depth of the water table in that area could be measured by seismic refraction methods. The problem of rising water tables is one which occurs commonly in irrigation districts. In some areas the problem is purely a local one in which only perched water tables, any within ten feet of the surface, are involved, but it is also possible that the level of the general water table over a large are may be raised by deep percolation. The State Rivers are Water Supply Commission have maintained a check on the water table depth in the Murray River Valley Irrigation District for some time by measurement in existing wells. These wells are not necessarily in the best positions, and some are falling in. The seismic method was considered as an alternative to expensive test boring for ground water measurement.

Seismic refraction velocities were measured in the Archaean or crystalline basement rocks at Mount Davies (SA) and Giles (WA) where the rocks are near the surface. Refraction velocities were measured in the Proterozoic outcrops of the Rawlinson Range and Lake Hopkins. Refraction velocities were measured in the Palaeozoic and Mesozoic rocks at Lake Christopher, and in the Mesozoic rocks at Iragana Turnoff. Those velocities were used as a basis for a suggested correlation between refractors recorded at traverses between Signpost and Mount Beadell. Reflection tecniques, as tried 9 yielded fair reflections at Mount Beadell, and doubtful reflection alignments at trig. point NMF 19. It is likely that the sedimentary basin shows an increasing thickness of sediments from Signpost to Mount Beadell, At Mount Beadoll there is at least 6000 ft of apparently post-Proterozoic sediments. The thickness and degree of metamorphism of Proterozoic ratio below this have not been determined. Present evidence suggests an area of uplift under Lake Breaden.