magnetic
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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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The presence of remanent magnetization must be correctly addressed in the inversion and interpretation of magnetic field data. Better knowledge and understanding of the influence of remanent magnetization will allow improved design of boreholes to test magnetic targets, thus reducing the risk of expensive misses, and also provide new geological insights regarding the distribution of geological events (including mineralization events) which have left a magnetic signature. To assist in this objective, we have designed a database for specification of magnetic field anomalies due substantially to remanent magnetization, and have initially populated this web-delivered database with just over 200 examples from across Australia. A map-based interface allows the user to determine which if any anomalies in an area are interpreted as due in substantial part to remanent magnetization, to recover the associated estimate of resultant magnetization direction, and in some cases to download models of the distribution of magnetization. We are presently researching the application of automated methods to recover magnetization estimates, which will provide a much greater number of estimates, albeit of lower reliability. We envisage a possible 'wiki'-like development of the database, so that once more fully established, it could grow by web upload of contributions from industry, government and academic geophysicists.
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The Australian Geological Survey Organisation flew an airborne geophysical survey of 49 000 line km over the entire Forbes 1:250 000 Map Sheet area during March, Apriland May, 1993. This survey, which formed part of the National Geoscience Mapping Accord, was flownalong east-west flight lines 200 m and 400 m apart at an altitude of 100m above ground level. The total magnetic intensity and gamma-ray spectrometric data which were collected during the survey, have been processed and are available for purchase, in both digital (position located data and grids) and map form, from the Australian Geological Survey Organisation
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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 GSQ Mt Isa West magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 89m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2006 by the QLD Government, and consisted of 63015 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 GSQ Mt Isa Southeast magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 88m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2006 by the QLD Government, and consisted of 100960 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 GSQ Mt Isa Southwest magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 88m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2006 by the QLD Government, and consisted of 139836 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. These line dataset from the Mount Isa South West, Qld, 2006 survey were acquired in 2006 by the QLD Government, and consisted of 139836 line-kilometres of data at 400m 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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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 Ashburton magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 89m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2006 by the WA Government, and consisted of 106235 line-kilometres of data at 400m 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. These line dataset from the Ashburton, WA, 2006 survey were acquired in 2006 by the WA Government, and consisted of 106235 line-kilometres of data at 400m line spacing 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 Musgrave Extensions magnetic grid geodetic has a cell size of 0.00083 degrees (approximately 88m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2006 by the WA Government, and consisted of 83777 line-kilometres of data at 400m line spacing and 60m terrain clearance.