Frome Rocks No. 1 Well, which is situated on the northern edge of the Jurgurra Terrace, drilled to 734 feet through Recent sand and the normal sequence of Jurassic sediments of the South Canning Basin and then entered the top of the Frome Rocks Salt Dome. The Frome Rocks Salt Dome consists of l,522 feet of dolomite breccia cap rock and 1,747 feet plus of salt. The base of the salt was not reached. The age of the sediments composing the salt dome is not known, but slender evidence suggests that the age is Devonian to Lower Carboniferous. The intrusion of the salt dome probably took place in post-Permian and pre-Jurassic times. No signs of hydrocaroons were seen in the well and no formation tests were conducted. The Frome Rocks No. 2 Well drilled through 206 feet of Recent and Jurassic sandstones, and a standard Permiansequence (3,351 feet thick) to 3,557 feet. A thick sequence of uppermost Devonian (Middle to Upper Famennian) sedimentswas encountered between 3,557 feet and the total depth of 7,504 feet. This thick Devonian succession (3,947 plus feet) has been divided into two formations, one of siltstone and shale with some limestone and sandstone, from 3,557 feet to 6,264 feet, and the other of siltstone, from 6,264 feet to 7,504 plus feet. The primary objective, the Ordovician, was not reached. Persistent, though slight, hydrocarbon shows occurred in several zones throughout the upper two-thirds of the Devonian in the form of fluorescence associated With limestones, and a spotty oil staining in the uppermost sandstone bed. No hydrocarbons were detected by gas detection equipment. None of the hydrocarbon shows was of sufficient significance to warrant testing. In the Frome Rocks area, there is an association of a salt dome, a thick impermeable sequence, source rockpotential, and some reservoir potential. Should the same association occur in other areas along the Jurgurra Terrace, particularly if the reservoir potential improves, the petroleum prospects of the area must be upgraded.

This report refers to a seismic reflection survey conducted near the town of Muttaburra in Queensland, between 16th October and 12th December, 1959, by Geoseismic (Australia) Ltd, for the Artesian Basin Oil Company Pty Ltd. The purpose of the survey was to determine the nature of any structures present and the thickness of the sedimentary rocks. A number of isolated reconnaissance lines were laid and the shot-points were placed at one or two mile intervals. The records were computed by jump correlation. One structural feature found as a result of the reconnaissance traverses was investigated by more detailed work. A northerly plunging anticline, with easterly dip contrary to the regional westerly dip was delineated on two reflecting horizons. The relief due to the easterly dip is approximately 250 feet on the deeper horizon and 200 feet on the shallower horizon. To investigate the area fully, it would be necessary to carry out a further seismic reflection survey using the continuous profiling method of recording and computing.

35% coverage east F55/B1-41 Contour interval: 10

Wolframite is the commonest source of tungsten, but scheelite is present in some mines. Minerals of bismuth, copper, molybdenum, lead, tin, and iron have been identified in association with the tungsten minerals. Minor amounts of gold are also present. The Hatches Creek Wolfram Field is situated near the north-eastern end of the Davenport Range in the Northern Territory. The Stuart Highway, a bitumenized road linking the port of Darwin with Tennant Creek and Alice Springs, crosses the Range at the north-western end. Wolfram deposits are present at Wauchope, The Devil's Marbles, Moscluito Creek, Kurunelli, Epenarra, Elkedra, and Hatches Creek; only the Wauchope and Hatches Creek deposits have proved to be economically important. The Wauchope deposits have been investigated by Sullivan (1952). The Hatches Creek Wolfram Field is defined for the purpose of this report as a roughly triangular area bounded by Hatches Creek, Mia Mia Creek, and the Hit or Miss Gully (Pl. 2). The area extends roughly seven miles in a northerly direction and is about three miles across at the base. Only two small tungsten bearing reefs and some reefs reputed to carry gold lie outside this area.

A seismic velocity survey was carried out in Associated Freney Oilfields Nerrima No. 1 Bore by the Bureau of Mineral Resources on the 10th August 1955. The well is situated on the Nerrima Dome in the Fitzroy Basin, W.A. Some trouble was experienced with cable breaks for the shallow part of the hole, but in general it was possible to recognise the true formation break. Average measured velocities ranged from 8000 ft/sec near the top to 12,200 ft/sec for the total depth of the bore.

Following a gravity survey of the Perth Basin in 1951-52 (Thyer and Everingham, 1956), in which it was indicated that a sedimentary thickness of about 35,000 ft was probably present in the Perth Basin, several seismic traverses were surveyed across the Basin. This Record deals with one such reflection traverse which was surveyed between Quindalup and Donnybrook. The purposes of the survey were to find the thickness and dip of the sediments and to discover any faulting or folding within them. Results of the survey were inconclusive regarding the depth to basement but indications are that it is at least 8000 ft in the deepest part of the B,sin along this traverse. The sediments appear to be folded and faulted. There is evidence for the existence of a major fault east of the Dunsborough Fault, and the existence of the Whicher Fault was tentatively confirmed.

Middalya in the Carnarvon Basin, Western Australia, during October 1955 by the Bureau of Mineral resources. The object of the survey was to assist in interpreting gravity results in the region. Prior to this survey the interpretation of the geology suggested that the deepest part of the Palaeozoic basin was in the Wandagee Hill area, but gravity results indicated that a basement ridge may exist in this same area. The seismic results indicate a sedimentary thickness of at least 17,000 ft between Wandagee Hill and Middalya and possibly 24,000 ft thickness to the east of Middalya. Although no useful information was obtained in the immediate vicinity of Wandagee Hill, extrapolation of results from farther east, suggests that the basement may be as shallow as 6000 ft just west of Wandagee Hill. This would confirm the interpretation of the gravity results at this location. The seismic cross-section shows that there may be a large elevation of the basement over a region about 20 miles west of Middalya between Shot-points 90 and 113. Although there is no direct evidence of this in the gravity results, it may be related to faulting, particularly a fault four miles east of Middalya that is indicated both by surface geology and by gravity results.

A seismic reflection traverse was surveyed across the Perth Basin, Uestern Australia, between the townships of Rockingham and Mundijong. It was planned in order to give information regarding the depth of the Basin and its structure adjacent to the Darling Scarp. Seismic refraction traverses were surveyed to give the longitudinal velocities in the near surface granitic gneisses on the Precambrian Shield, and in the Cardup Series (Proterozoic) abutting the Darling Scarp. At least 14,000 ft of sediments are indicated in the deepest part of the Basin but there is no clear seismic evidence of what a maximum thickness might be. Seismic reflection results indicate that the sediments on the west of the Darling Scarp abut the older rocks on a plane that dips at about 60 degrees to the west and that cuts the surface some distance in front of the present position of the scarp. This suggests that the Darling Scarp at Eundijong is the surface expression of a normal fault. However, the presence of reflection alignments east of this postulated fault plane, and thus apparently arising within the granitic gneisses, is contrary to the fault hypothesis. The true nature of the tectonic features is thus unresolved. Seismic results indicate that faulting occurred within the Basin and such faulting may have completed closure of possible oil traps. Further seismic investigation of the faults and associated structures is recommended.

In July and August 1957 an experimental seismic survey was done in the Oodnadatta area of the Great Artesian Basin. The purposes of the survey were to find whether reflections could be recorded from beneath duricrust, a siliceous surface deposit, and whether structures mapped by surface geological methods persist with depth. Reflections were recorded from beneath the duricrust using shallow pattern holes and six geophones per trace; the sub-surface structure was mapped with reasonable accuracy. In areas where the duricrust is eroded, reflections of fair quality were obtained using a single shot-hole and six geophones per trace. A seismic reflection traverse across the Oodnadatta anticline indicated that the structure was present in a horizon which corresponds to the top of the artesian aquifer at a depth of about 1000 ft below datum (400 ft above MSL). The seismic results indicated that the anticline was of smaller relief than had been e stimated from surface mapping. There was a change from fair-quality persistent reflections at shallow depths to poor-quality less numerous reflections with sporadic dips at greater depths; this probably represents the base of the Cretaceous. The greatest depth from which Cretaceous sediments were recorded was about 2350 ft below datum. Reflection depths computed by seismic methods correspond closely with lithological boundaries, and in particular the base of the Cretaceous sediments, encountered in the Santos No. 1 bore. The results of a refraction traverse on the crest of the Oudnadatta anticline show the presence of a 'basement' refractor with a velocity of 13,900 ft/sec at a depth of about 1245 ft below datum. There is slight evidence of a refractor with a substantially higher velocity at about twice this depth. The 'basement' velocity of 13,900 ft/sec is consistent with the assumption that there is a pre-Cretaceous layer between the Cretaceous sediments and the Precambrian basement complex.

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.