From 1 - 10 / 1916
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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.

  • A request was received in December, 1951, from the Director of Ordnance and Underwater Weapons of the Department of the Navy for assistance in selecting an area suitable for the electrical balance testing of the pistol-firing rod unit of the torpedo. It was desired that this site should be at the R.A.N. Torpedo Establishment at Neutral Bay, Sydney, New South Wales. The only condition laid down in the relevant specification is that "the rod may be supported in a suitable wooden structure or in such other manner provided that the complete rod unit is not less than ten feet from any ferro-magnetic materials". In order to arrive at a more specific definition of the requirements for the testing site, the problem was discussed with the Chief Superintendent and officers of the Torpedo Establishment. The appropriate test specifications were consulted and a series of measurements were carried out to determine the actual requirements. The magnetic investigations described in this report were carried out in August, 1952, and the overall results and conclusions were communicated verbally at that time to the officers concerned.

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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 Torrens ReducedToPole 1stverticalderivative grid geodetic is the first vertical derivative of the TMI RTP grid of the Torrens Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey. This grid has a cell size of 0.0004 degrees (approximately 41m) , and given in units of nT per metre (nT/m). The data used to produce the TMI grid was acquired in 2017 by the SA Government, and consisted of 83653 line-kilometres of data at 200m line spacing and 60m terrain clearance. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model using a data representative date and elevation representative of the survey. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the TMI RTP grid of the Torrens Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey to produce this grid. This grid was calculated using an algorithm from the INTREPID Geophysics software package. This grid shows the magnetic response of subsurface features with contrasting magnetic susceptibilities. The grid can also be used to locate structural features such as dykes.

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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 magnetic grid has a cell size of 0.0004 degrees (approximately 41m).The data are in nanoTesla (or nT). The data used to produce this grid was acquired in 2017 by the SA Government, and consisted of 83653 line-kilometres of data at 200m line spacing and 60m terrain clearance. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model using a data representative date and elevation representative of the survey.

  • Categories  

    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 Lake Eyre - TMI grid (AWAGS) has a cell size of 0.0004 degrees (approximately 41m). 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 92215 line-kilometres of data at 200m line spacing and 60m terrain clearance. To constrain long wavelengths in the grid, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey grid.

  • Categories  

    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 Barton ReducedToPole 1stverticalderivative grid geodetic is the first vertical derivative of the TMI RTP grid of the Barton Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey. This grid has a cell size of 0.00042 degrees (approximately 43m) , and given in units of nT per metre (nT/m). The data used to produce the TMI grid was acquired in 2017 by the SA Government, and consisted of 111668 line-kilometres of data at 200m line spacing and 60m terrain clearance. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model using a data representative date and elevation representative of the survey. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the TMI RTP grid of the Barton Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey to produce this grid. This grid was calculated using an algorithm from the INTREPID Geophysics software package. This grid shows the magnetic response of subsurface features with contrasting magnetic susceptibilities. The grid can also be used to locate structural features such as dykes.

  • Categories  

    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 Fowler ReducedToPole 1stverticalderivative grid geodetic is the first vertical derivative of the TMI RTP grid of the Fowler Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey. This grid has a cell size of 0.00042 degrees (approximately 43m) , and given in units of nT per metre (nT/m). The data used to produce the TMI grid was acquired in 2017 by the SA Government, and consisted of 94903 line-kilometres of data at 200m line spacing and 60m terrain clearance. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model using a data representative date and elevation representative of the survey. A first vertical derivative was calculated by applying a fast Fourier transform (FFT) process to the TMI RTP grid of the Fowler Airborne Magnetic Radiometric and DEM Survey, SA, 2017 survey to produce this grid. This grid was calculated using an algorithm from the INTREPID Geophysics software package. This grid shows the magnetic response of subsurface features with contrasting magnetic susceptibilities. The grid can also be used to locate structural features such as dykes.

  • Categories  

    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 Fowler TotalMagneticIntensity 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 2017 by the SA Government, and consisted of 94903 line-kilometres of data at 200m line spacing and 60m terrain clearance.

  • Forward modelling of potential field data, combined with new geological mapping and deep seismic reflection transects acquired by the Australian Geodynamics Cooperative Research Centre (AGCRC) and NSW Department of Mineral Resources, has led to iterative testing of models of crustal architecture of the eastern Lachlan Orogen in New South Wales. This integrated analysis has led to new conclusions about the subsurface that are unlikely to be deduced solely from any of the individual data sets used. The overall Palaeozoic history of the eastern Lachlan Orogen, implied by the integrated analysis of geophysical and geological data sets, involves: ? formation of an Ordovician oceanic island arc (of uncertain polarity); ? Early Silurian east-directed overthrusting and deformation of the arc, partly due to crustal thickening by thrust stacking; ? Early Silurian to Early Devonian rifting, resulting in the dismemberment of the deformed arc, and formation of a series of arc fragments separated by marine basins; ? folding of these basins during the Early to Mid Devonian, with some granite magmatism; ? Late Devonian terrestrial sedimentation; ? Carboniferous thin-skinned thrust stacking involving east- and west-directed transport, and slicing of the upper structural level of earlier antiformal stacks, together with granite roof zones; and ? Carboniferous granitic magmatism Key words: Seismic reflection; gravity; magnetics; forward modelling, tectonics.