magnetics
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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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An earlier report (Record 1950/041) has described the geophysical survey carried out early in 1950 on the Renison Bell tin field. The present report deals with the work of a second field season which commenced in November 1950 and continued until June 1951. The methods used were again the magnetic and self-potential. The 1950 survey was extended to the south and east by continuing along the Renison Bell Hill base-line a further 1000 feet south and reading stations on both sides of this base-line along traverses extending from the main quartz-porphyry dyke to the headwaters of the Montana Creek. In addition, some of the traverses were extended over the saddle between Dreadnought and Stebbins Hills as far as the Boulder tramway. The report gives an account of the survey work and its results, and provides recommendations for future testing. The geological features of the area covered by the present geophysical survey are briefly described.
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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 GSSA Coompana Infill TMI Grid Geodetic has a cell size of 0.00042 degrees (approximately 43m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2015 by the SA Government, and consisted of 286817 line-kilometres of data at a line spacing between 200m and 400m, and 80m 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. This GSSA Coompana TMI Grid Geodetic has a cell size of 0.00083 degrees (approximately 86m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2015 by the SA Government, and consisted of 286817 line-kilometres of data at a line spacing between 200m and 400m, and 80m terrain clearance.
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This report deals with the application of geophysical methods (other than radiometric) to the Coronation Hill Radioactive Deposit. Results of radiometric gridding of the surface and costeans, field sludge assays, and radiometric drill hole logging are not treated as these are included in entirety in R.B. Allen's report "The Coronation Hill Uranium Prospect," Bureau of Mineral Resources Record 1954/17. Structural indications from magnetic evidence are discussed. These comprise several faults, or zones of weakness, one of which may coincide with the axis of the surface radio-activity. Several interesting magnetic features for which no cause can be proposed are also noted. The highly uncertain nature of the deductions made is emphasised. The method of approach to geophysical applications at Coronation Hill is detailed, and recommendations are made for possible future work.
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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 NTGS Delamere TMI Grid Geodetic has a cell size of 0.00083 degrees (approximately 91m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2015 by the NT Government, and consisted of 96790 line-kilometres of data at 400m line spacing and 80m 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. This NTGS SpiritHills TMI Grid Geodetic has a cell size of 0.00083 degrees (approximately 91m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2015 by the NT Government, and consisted of 96790 line-kilometres of data at 400m line spacing and 80m 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. This GSSA p1280tmig has a cell size of 0.00042 degrees (approximately 44m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2017 by the SA Government, and consisted of 109753 line-kilometres of data at 200m line spacing and 60m 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. This GSSA Warrina Magnetic Grid Geodetic has a cell size of 0.00042 degrees (approximately 44m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2017 by the SA Government, and consisted of 135932 line-kilometres of data at 200m line spacing and 60m terrain clearance.
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The establishment of seismological and magnetic observatories at Heard Island is described. Brief descriptions and photographs of the huts and instruments are given. Earthquake phases recorded between April 1951 and February 1952 are listed, as are absolute magnetic observations made between July 1951 and January 1952. Although Heard Island has two active volcanic craters, the region is not very active seismically. Only two near earthquakes were recorded, both probably 2°.9 distant along the Kerguelen ridge. The absolute magnetic observations showed that the high rate of secular change in declination and horizontal intensity is continuing.