mag
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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.
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Legacy product - no abstract available
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Legacy product - no abstract available
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This report describes the results of geomagnetic measurements made at repeat stations in the northern Prince Charles Mountains (PCMs) in January 1992 and at Heard Island in February 1992. The PCM survey covered 7of the 9 stations occupied by Crosthwaite in Jan/Feb 1990. The Heard Island work was a reoccupation of a previous magnetic station and observatory site. Multiple sets of DIF or HDF observations were made at each station and sunshots, pier differences and local F surveys were carried out at most stations for confirmation of the 1990 measurements. Variometer records for the 3-5 day occupation of each station were obtained using two portable fluxgate magnetometers developed by F Chamalaun, Flinders University. One was left installedat the first repeat station, the other was carried and reburied at each repeat station. The area covered by the survey was approximately 160 km by 130 km. Station descriptions based mainly on those provided by Crosthwaite are included to facilitate reoccupation. References to earlier geophysical and surveying occupations are given in Crosthwaite (1992).
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Legacy product - no abstract available
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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. This GSWA Holleton North magnetic grid geodetic has a cell size of 0.001 degrees (approximately 103m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 1997 by the WA Government, and consisted of 4255 line-kilometres of data at 400m line spacing and 40m terrain clearance.
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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 Southern Yilgarn (Boorabbin, Lk Johnstn, Sthn Cross, W Kal.), WA, 2004 survey were acquired in 2004 by the WA Government, and consisted of 83101 line-kilometres of data at a line spacing between 200m and 200m, and 60m 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.
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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. This GSWA Hyden Southern Cross magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 85m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2004 by the WA Government, and consisted of 62585 line-kilometres of data at 400m line spacing and 60m terrain clearance.
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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.
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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. This GSWA Anketell magnetic grid geodetic has a cell size of 0.00028 degrees (approximately 30m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2002 by the WA Government, and consisted of 23340 line-kilometres of data at 150m line spacing and 25m terrain clearance.