seismic refraction
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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.
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The Bureau of Mineral Resources'No. 2 seismic party conducted a Survey over the Palm Valley Anticline 80 miles west of Alice Springs, from 2nd November to 22nd November 1961. The seismic reflection method showed (a) the anticlinal structure existed at depth and (b) at the northern end of the main north-south traverse in the Missionary Plains north-dipping reflections were recorded from about 2500-ft depth. A shallow refractor was recorded in which the velocity Was 17,800 ft/sec. This refractor, which could not be positively identified, prevented, any useful deeper refraction information being recorded.
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Details and results are given of a seismic refraction survey made at the request of the Hydro-Electric Commission of Tasmania, to investigate the proposed site for a power station with penstock lines and tail race. The power station is part of the Wayatinah "A" project. The object of the survey was to determine the thickness of the alluvial gravel formation on the river flat, the weathered section of the sandstone and the dolerite, and to indicate the presence of shear zones. Three traverses parallel to the proposed penstock line, and 100 feet apart, and three cross traverses were surveyed in January and February, 1954. After completion of the original survey two additional traverses were surveyed on the location chosen for the power station, penstock lines and tail race site.
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The Bureau of Mineral Resources made three seismic surveys in the Ngalia Basin, Northern Territory, during 1967 to 1969 as part of a comprehensive geological and geophysical investigation of the structure and stratigraphy of the basin. L097 is the third survey done in 1969. The project was aimed at delineating the configuration of the basin, within which outcrops are sparse, and providing information pertaining to its depositional and tectonic history. Investigation of the extent of Lower Palaeozoic sedimentation was considered to be important in assessment of the petroleum prospects of the basin. Raw data for this survey are available on request from clientservices@ga.gov.au - Quote eCat# 75660
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The Geoscience Australia Onshore Seismic GIS layer is layer showing the locations of Onshore Seismic Survyes carried out by Geoscience Australia and it's predecessors, Australian Geological Survey Organisation (AGSO) and the Bureau of Mineral Resources (BMR). The layer contains URL link to free downloadable data. The data includes processed data in SEGY format. The metadata includes acquisition reports, processing reports, processed images and so on. The data acquisition was carried out in Australia from 1949 to present by Geoscience Australia and various partners such as State and Geologcial Survey Organisations. The set of reflection and refraction data comprises over 12,000 km of coverage, and provides an insight into the variations in crustal architecture in the varied geological domains.
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Aeromagnetic and gravity surveys were made in the Tambo-Augathella area by Magellan Petroleum Corporation in 1959 and 1960 respectively. A probable fault shown in the magnetic interpretation is almost coincident with a zone of steep gravity gradients which was interpreted as indicative of a fault or of steeply dipping strata. However, the normal gravity interpretation would indicate a deeper cross-section to the south-east of this zone, whereas the magnetic interpretation suggests that the fault is downthrown to the northwest. The present survey was undertaken by the Bureau of Mineral Resources to find out which interpretation was the more probable. A reflection seismic traverse was shot at right angles to the closed gravity 'high' and across the zone of steep gravity gradients. Results show that the closed gravity 'high' is the expression of an anticline and that the zone of stoep gravity gradients is caused by steep dip to the south-east on the flank of the anticline. The gravity interpretation is therefore found to be more representative of actual conditions.
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Between August and December 1960 a seismic party from the Bureau of Mineral Resources carried out a reconnaissance seismic survey, using reflection and refraction techniques, across the Murray Basin. Traverses were placed at selected localities at Carrathool, Hay, Maude, Balranald, Wentworth, Merbein, Lake Victoria, and Loxton. In general, the results show that the Basin, at least along the line of traverse, consists of essentially undisturbed sediments above a high-velocity basement. The thickness of Basin sediments ranges from about 900 ft at Carrathool to 2200 ft at Lake Victoria and Merbein. Most of the sediments are of Tertiary age, with Mesozoic at Loxton and Wentworth and perhaps at other traverses in the western part of the Basin. The seismic velocity in the sediments has a typical value of about 6000 to 7000 ft/sec, while the velocity in the basement ranges from 15,750 ft/sec (at Hay) up to 20,000 ft/sec (at Lake Victoria). The geological nature of basement is not known, but it is considered that it definitely marks the floor of the Tertiary (or Tertiary - Mesozoic) basin. Refraction velocities alone are of doubtful value in identifying the floor, as it is known that crystalline basement, metamorphosed sediments, or unmetamorphosed sediments such as limestone, may have velocities within this range.
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A seismic reflection survey was made to the south-west, south and east of the Poole Range Structure, Kimberley Division, W.A. as an extension of a previous seismic survey. The results obtained confirm the surface information and show the existence of an anticlinal structure l the axis of which plunges to the east and whose axial plane probably dips to the south. A total thickness of sediments of the order of 20,000 feet is shown. Some slight evidence of deep faulting down to 10,000 feet was recorded, but is not conclusive. Insufficient evidence was obtained to select a site for a test bore, but further seismic work is not recommended at present.
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Details and results are given of a seismic refraction survey made at the request of the Hydro-Electric Commission of Tasmania, to investigate the site of the western portal of the proposed Mossy Marsh Tunnel. The tunnel is part of the No. 2 Tarraleah Canal project to transport water from Lake King William to Tarraleah Power Station. The primary object of the survey was to determine the thickness of till overlying the dolerite bedrock, and hence contours of the bedrock surface.
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Seismic reflection traverses were surveyed across the Perth Basin at Cookernup, W.A. These traverses were planned to find the thickness and dip of the Basin sediments adjacent to the Darling Scarp and to discover any faulting or folding within them; also to determine the applicability of the seismic method as a tool for both regional and detailed investigation in this area. Seismic refraction traverses were surveyed to help in the solution of problems encountered in the interpretation of the reflection cross-sections. The survey indicated a considerable thickness of sediments about 20,000 ft, at the eastern margin of the Basin near the Darling Scarp, and suggested tectonic structure that is not indicated in surface geology, The reflection traverses indicated that sediments (presumably Lower Palaeozoic or Precambrian) lying deep in the Perth Basin may continue underneath the Darling Scarp and abut the granitic gneisses etc. of the Western Australian Shield on an overthrust fault plane. The overthrust fault, if it exists, does not reach the surface, but is covered to a depth of possibly some few hundred feet by younger sediments and also by alluvium eroded from the Darling Scarp. Some reflection and refraction shooting was done in an attempt to test this and other hypotheses, but the results crc inconclusive. Gravity results strongly suggest a normal fault, and if normal faulting is the case, the reflections from beneath the outcropping basement are possibly derived from shear zones, Some probable 'reflected refractions' were also observed. There is scope for further seismic testing but it is considered that conclusive evidence could only be provided by drilling.