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 Southwest Margin of Australia includes the Paleozoic to Mesozoic Perth basin. Depth-to-basement and basement structure and composition across this region remain poorly understood due to a limited extent of exposed basement outcrop, few wells intersect basement and the lack of resolvable basement horizon in many of the seismic lines. This study uses the integrated modelling and interpretation of all available geophysical and geological datasets to produce new interpretive maps of basement architecture, composition and structural fabric to better characterise the nature of basement across the region. The basement domain, structure and composition maps have been constructed through the integrated interpretation of all available geological and geophysical datasets, including outcrop, wells, geochronology, seismic, gravity, magnetic and bathymetry datasets. These products are predictive tools for better understanding structural reactivation patterns and associated changes in basin geometry through time, as well as variations in basement derived heat flow. A depth-to-basement model was developed using the Spector and Grant method, implemented using custom software. Depths are measured from straight line segments in the azimuthally averaged power density spectrum of sub-sectioned magnetic grids. This allows additional geological and geophysical data (e.g. wells, surface outcrop, gravity and seismic interpretations) to be integrated into the workflow, resulting in a more geologically plausible model. The model provides a new view of Perth basin geometry, not obtainable from seismic data alone, which highlights the location and geometry of key depocentres and provides additional constraints on the possible thickness of pre- and early syn-rift sediments.
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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 Lake Muir TMI Grid Geodetic has a cell size of 0.00063 degrees (approximately 63m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2012 by the WA Government, and consisted of 126090 line-kilometres of data at a line spacing between 200m and 300m, and 50m 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 GSWA Charnley TMI Grid Geodetic has a cell size of 0.00042 degrees (approximately 45m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2011 by the WA Government, and consisted of 145084 line-kilometres of data at a line spacing between 200m and 800m, and 50m 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 GSWA Widgiemooltha North TMI Grid Geodetic has a cell size of 0.00021 degrees (approximately 21m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2013 by the WA Government, and consisted of 92768 line-kilometres of data at 100m line spacing and 50m 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 GSWA Kalgoorlie East TMI Grid Geodetic has a cell size of 0.00021 degrees (approximately 22m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2013 by the WA Government, and consisted of 121572 line-kilometres of data at 100m line spacing and 50m 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 GSWA Widgiemooltha South TMI Grid Geodetic has a cell size of 0.00021 degrees (approximately 21m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 2012 by the WA Government, and consisted of 131391 line-kilometres of data at 100m line spacing and 50m terrain clearance.
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20 nT
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20 nT
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20 nT