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

  • F55/B1-13 Vertical scale: 100

  • The position of the area described here as the 'Headwaters of the Burke River in the tropical zone of Australia is evident from the locality map, Figure 1. Topographically it is part of the Selwyn Range, which is a divide composed mainly of metamorphosed Precambrian rocks. These are described by Carter (1959), Carter & Brooks (1960), and Carter, Brooks, & Walker (1961). Structurally it is part of the Burke River Outlier, within which the Selwyn Range is built of Cambrian sediments, which are referred to as 'the Selwyn Range sequence'. This sequence is preserved here owing to post. Cambrian faulting that involves the whole Outlier; the Outlier itself is the northern segment of the Burke River Structural Belt, which extends south for another hundred miles. The headwaters of the Burke River are in the Selwyn Range, north-western Queensland. Exploration began in 1860; Cambrian fossils were discovered in 1931. Mapping by the Commonwealth Bureau of Mineral Resources (1952-1958) amplified the knowledge of the geology and palaeontology of the area. Four formations (Roaring Siltstone, Devoncourt Limestone, Selwyn Range Limestone, and O'Hara Shale) and one unit of beds (Mount Birnie Beds) constitute the Cambrian of the Selwyn Range sequence. The Mount Birnie Beds (sandstone, arkose, regolithic clay) occurs as erosional residuals on the basement. Unconformably above follows the Roaring Siltstone with shale and sandstone interbeds; above it rests the Devoncourt Limestone, flaggy and bituminous; the next higher is the Selwyn Range Limestone, a caIcilutite with chert and marly interbeds, overlain by the O'Hara Shale with interbeds of chert and sandstone. A Mesozoic conglomerate (erosional residuals) and alluvial deposits conclude the sequence.The position of the area described here as the 'Headwaters of the Burke River in the tropical zone of Australia is evident from the locality map, Figure 1. Topographically it is part of the Selwyn Range, which is a divide composed mainly of metamorphosed Precambrian rocks. These are described by Carter (1959), Carter & Brooks (1960), and Carter, Brooks, & Walker (1961). Structurally it is part of the Burke River Outlier, within which the Selwyn Range is built of Cambrian sediments, which are referred to as 'the Selwyn Range sequence'. This sequence is preserved here owing to post. Cambrian faulting that involves the whole Outlier; the Outlier itself is the northern segment of the Burke River Structural Belt, which extends south for another hundred miles. The headwaters of the Burke River are in the Selwyn Range, north-western Queensland. Exploration began in 1860; Cambrian fossils were discovered in 1931. Mapping by the Commonwealth Bureau of Mineral Resources (1952-1958) amplified the knowledge of the geology and palaeontology of the area. Four formations (Roaring Siltstone, Devoncourt Limestone, Selwyn Range Limestone, and O'Hara Shale) and one unit of beds (Mount Birnie Beds) constitute the Cambrian of the Selwyn Range sequence. The Mount Birnie Beds (sandstone, arkose, regolithic clay) occurs as erosional residuals on the basement. Unconformably above follows the Roaring Siltstone with shale and sandstone interbeds; above it rests the Devoncourt Limestone, flaggy and bituminous; the next higher is the Selwyn Range Limestone, a caIcilutite with chert and marly interbeds, overlain by the O'Hara Shale with interbeds of chert and sandstone. A Mesozoic conglomerate (erosional residuals) and alluvial deposits conclude the sequence.

  • Ice thickness measurements were made in 1961 by seismic methods on a line southward from S-2, a glaciological station 50 miles east-south-east of Wilkes Base, Antarctica. The traverse constituted the first year's work of a three-year programme. The results showed that the rock underlying the ice dips below sea level at a point between 20 and 40 miles south of S-2. It remains below sea level at all the locations occupied to the south, as far as 280 miles south of S-2, where the rock surface is again above sea level. The main feature is a valley disclosed in the rock formation between 40 and 80 miles south of S-2. Midway between these two points the rock lies at approximately 7500 ft below sea level. The positions of the Totten Glacier and the John Quincy Adams Glacier suggest that the valley may have been responsible for their formation.

  • 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.

  • 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.

  • The Bureau of Mineral Resources Seismic Party No. 2 conducted a survey from 15th May to 25th August 1961 in the Amadeus Basin. Reflection and refraction traverses were shot at intervals, along or near the Alice Springs/Port Augusta railway line, from Polhill in the north to Finke in the south. In broad terms the object of the survey was to obtain across the Amadeus Basin a north-south seismic cross-section that would aid in investigating the stratigraphic cross-section and structural relations especially on the southern margin of the Basin. Access and drilling problems caused the progress of the survey to be slow. The statistics of the operation are included in three appendices. During the course of the seismic survey, the Bureau also made gravity surveys covering the area; gravity-meter readings were made along all seismic traverses.