From 1 - 10 / 1929
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    Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Murrindal, Vic, 1996 VIMP Survey (GSV3060) survey were acquired in 1995 by the VIC Government, and consisted of 15589 line-kilometres of data at 200m line spacing and 80m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.

  • Legacy product - no abstract available

  • Legacy product - no abstract available

  • The Australian Geological Survey Organisation flew an airborne geophysical survey of 68 300 line km over the Frome and southern Callabonna 1:250 000 map Sheet areas from August to November 1995. The survey was flown along east-west flight lines spaced 400 metres at an altitude of 80m above ground level. The total magnetic intensity, gamma-ray spectrometric and digital elevation model data which were collected during the survey have been processed and are available for purchase, in both digital (point located data and gridded) and map form, from the Australian Geological Survey Organisation.

  • Legacy product - no abstract available

  • The Tilt-Depth method is investigated as a means to rapidly derive estimates of depth to basement from magnetic data. This method involves calculating the tilt angle from reduced-to-pole magnetic data. Magnetic sources are assumed to have simple contact geometry. The depth to these sources can be estimated from the distance between contours of the mapped tilt angle. Previous studies have demonstrated that this method yields useful results for continent and basin-scale analysis. Here we test the potential of this method to be used for detailed analysis of high-resolution continent-wide data. The Australian continent comprises a collage of ancient cratonic blocks and orogenic belts. These ancient basement rocks are at or near the surface over large areas of the continent, while in other areas the basement is buried beneath up to 10 km of sediments in Neoproterozoic and younger basins. Mapping the thickness of these sediments across the continent is important for a number of reasons - important amongst these is the need to define the depth to basement in areas of relatively thin cover adjacent to exposed cratonic rocks. Exposed expressions of the basement rocks are often richly mineralised. Efficient targeting of deposits located under cover at up to 1 km depth requires mapping of depth to basement around the margins of exposed basement areas across the whole of Australia. Geophysical data provide a means to achieve this, in particular the continent-wide compilation of high resolution aeromagnetic surveys.