Geoscience Australia in collaboration with the Geological Survey of NSW acquired the Yathong Trough Deep Crustal Seismic Survey in 2013. The survey involved the acquisition of seismic reflection and gravity data along two traverses, 13GA-YT1 (98km) and 13GA-YT2 (132km) near Hillston, NSW. The purpose of the survey was to acquire new data to better understand the regional geology and major structured of the Yathong Trough within the Darling Basin, NSW. Funding was from the Geological Survey NSW through the New Frontiers Initative. Raw data for this survey are available on request from clientservices@ga.gov.au

Despite long history of studies the Wallaby Plateau offshore Western Australia remains a controversial feature. Analysis of interval seismic velocities from Geoscience Australia's 2008/09 seismic survey 310 in conjunction with seismic reflection interpretation provides new insights into the geology of the Plateau. Seismically distinctive divergent dipping reflector (DDR) packages have been identified. The seismic character of the DDR packages is similar to seaward dipping reflector (SDR) packages of inferred volcanic composition. Initial analysis of seismic velocity profiles indicated affinities between the DDR packages and known sedimentary strata in the Houtman Sub-basin. Effect of water loading on seismic velocities is commonly ignored in offshore studies. However, direct comparative analysis of interval velocity patterns between areas of significantly different water depth requires various water pressure related changes in velocity to be accounted for. There are controversies in methodology and application of water depth adjustment to seismic velocities, and presentation of velocity models as function of pressure rather than two-way time, or depth emerges as a possible solution. Water depth adjustment of seismic velocities analysed in our study reduces distinction between SDRs, DDRs and sedimentary strata such that discrimination between volcanic and sedimentary strata in DDR or SDR packages is equivocal. A major uncertainty of this interpretation is due to a lack of the reference velocity model of SDRs and DDRs investigated globally.

TBA

A method for calibrating seismic stacking velocities against velocities from well measurements has been developed to quantitatively assess the validity of stacking velocities in the vicinity of boreholes and to improve quality of stacking velocities for use in regional depth conversion of interpreted seismic horizons. Accurate depth conversion of seismic interpretation is vital for use as constraints in gravity modelling and in other basin modelling tasks. Examples of this methodology are given for the northern Perth Basin, Australia. The suggested workflow for calibrating seismic stacking velocities against well velocities in a simplified form is as follows: 1. Check each velocity dataset for errors 2. Modify the datum of each dataset to the sea floor 3. Convert all datasets to two-way time and depth domain 4. Resample all velocity datasets to the same two-way time intervals 5. Cross plot stacking velocity depths near a well site with corresponding well depths for equal two-way times 6. Fit a linear polynomial to this cross-plot (higher order polynomials were tried also), and determine calibration coefficient from the gradient of the polynomial. 7. Grid calibration coefficients 8. Multiply depths derived from stacking velocities by calibration coefficient grid An assessment of depth conversion errors relative to wells shows that this methodology improves depth conversion results to within ±50 m down to the maximum well depth analysed (3.5 km below sea floor); this depth uncertainty translates into a modelled gravity anomaly error of about ±20 gu, which is acceptable for regional scale gravity modelling.

The preliminary investigation was made when the Bureaut s seismic party was held up by flooded rivers, while on its way t o Christmas Creek in May, 1954. Results show that the seismic aethod is applicable to the Broome area, and that a sedimentary section of the order of 12,500 feet exists. They further show that a syncline and anticline not known from the surface geology may possibly exist at depth.

On 12th July 1960, a velocity survey of the A.A.O. Pickanjinnie No. 1 bore was made by the Bureau of Mineral Resources. The bore had been drilled to a depth of 5218 ft and was surveyed to the bottom. The average velocities for the Mesozoic rocks and the Timbury Hills Formation are similar to those measured in the Timbury Hill No. 2 bore. However, it seems impossible to correlate individual units within the Mesozoic sequence according to their velocity.

Following a month of preliminary experimental seismic work in the latter part.of 1964 the Bureau of Mineral Resources carried out a reconnaissance seismic survey of the southern part of the Georgina Basin, mainly in the Northern Territory, from April to October 1965. In most areas reflections proved very difficult to obtain. A number of different techniques were tried, including various shot andgeophone pattern arrangements, noise testing,collinear offset shooting, airshooting and multiple coverage, but no technique was found which was generally successful in providing useful reflections. The seismic results tended to confirm gravity indications that there is a shelf area between BMR 12 Bore and Tobermory and provided no indications that there are deep Palaeozoic troughs similar to the Toko -Syncline in the survey area.

The Bureau of Mineral Resources seismic party carried out a seismic survey in the Bonaparte Gulf area of north-western Australia between 16th June and 13th October, 1956. The initial objects of the survey were to obtain regional information on the thickness of the sedimentary rocks and on the tectonics of the Bonaparte Gulf Basin, and to establish the applicability of the seismic method in the area. During the course of the survey the party was directed to transfer its attentions to obtaining some detailed information on the Spirit Hill Anticline. This latter work was carried out in response to an application by Westralian Oil Pty. Ltd., which was anxious to select sites for a test boring programme. The seismic results indicate a maximum thickness of sediments of about 20,000 feet in the Carlton Basin and 14,000 feet in the Burt Range Basin. The rocks in both these basins have been folded to a considerable extent and the reflections suggest unconformities within both basins. The seismic reflection method proved successful in indicating geological structure at depth in most of the areas tested.

Geoscience Australia acquired the Papunya Seismic Reflection Survey in 2010. The survey involved the acquisition of high resolution seismic reflection data along a single 11.5km traverse (10GA-PA1). The purpose of the survey was to obtain information on key palaeovalley characteristics for potential groundwater studies. This dataset contains seismic data and images only, a full report on the results of the palaeovalley study can be found in GA Record 2012/09. Raw data for this survey are available on request from clientservices@ga.gov.au

Ice thickness measurements carried out by field parties based on Mawson during 1957-59 consisted of: (:) regional traverses in the form of closed loops extending several hundred kilometres inland from Mawson; (ii) semi-detailed traverses in the vicinity of a line of ice flow stakes about 25 Km from Mawson. The regional traverses showed that, beyond about 175 Km inland, the area surveyed is influenced strongly by the Lambert Glacier - Amery Ice Shelf system situated some 200 Km to the East. Preliminary contour plans of the ice and rock surfaces show fairly close correspondence. A sub-glacial extension of a range of mountains outcropping through the ice 80 Km to the East of the traverses was found. Work along the semi-detailed traverses close to Mawson detected sub-glacial extensions of the outcropping mountain ranges in the area. These extensions may explain the general direction of the coastline near Maws on.