Keyword

magnetic

1929 record(s)
 
Type of resources
Keywords
Publication year
Service types
Scale
Topics
From 1 - 10 / 1929
  • 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. These line dataset from the Australia-Wide Airborne Geophysical Survey 2 (AWAGS2), 2007 survey were acquired in 2007 by Geoscience Australia at 75000m line spacing and 80m terrain clearance.

  • 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.

  • Interpretation of gravity and magnetic data in the vicinity of the deep seismic lines 10GA-CP1, 10GA-CP2 and 10GA-CP3, which cross the Capricorn Orogen of Western Australia. Interpretation techniques untaken include multiscale edge detection (worms), 2.5D forward modelling and unconstrained 3D inversion.

  • Legacy product - no abstract available

  • 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. These line dataset from the Velkerri, NT, 1995 survey were acquired in 1995 by the NT Government, and consisted of 7625 line-kilometres of data at 500m 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.

  • 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 Cue Kirkalocka Ninghan Yalgoo Magnetic Grid Geodetic has a cell size of 0.00083 degrees (approximately 87m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 1995 by the WA Government, and consisted of 124601 line-kilometres of data at a line spacing between 200m and 400m, and 60m terrain clearance.

  • 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. These line dataset from the Childara-Gairdner, SA, 1961 survey were acquired in 1961 by the SA Government, and consisted of 23800 line-kilometres of data at 1600m line spacing and 150m 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.

  • The map addresses the distribution of Archaean rocks of the Yilgarn Craton but includes interpretation of overlying Proterozoic rocks (Yerida, and Earaheedy groups). Interpretation was undertaken at 1:250 000 scale for AGSO aeromagnetic data (400m and 1500m linespacing data) and for Fugro Airborne Surveys Pty.Ltd. coverage of the Menzies Sheet (200m linespacing data), and 1:500 000 scale for Fugro Airborne Surveys Pty.Ltd. coverage of the Kalgoorlie, Kurnalpi and Widgiemooltha Sheets (200m linespacing data). The Archaean rocks are subdivided into undivided gneiss-migmatite-granite (Agmg), banded gneiss (Agn), greenstone (Aa), and granite plutons (Ag). Where important relative differences in magnetisation are mapped, the geophysical map units include the suffixes _h (high), _m (medium), _l (low) and _r (remanent) for the level of magnetisation. Dykes, faults, and unassigned small intrusives are also mapped. The map is derrived from a subset of a more extensive interpretation covering the exposed extent of the Yilgarn Craton.

  • The Australian Geological Survey Organisation (AGSO) flew an airborne geophysical survey of 62 542 line km over Pasmore, Benagerie, Lake Charles, Kalabity and Mulyungarie 1:100 000 map Sheet areas on the Curnamona 1:250 000 map Sheet area in South Australia from April to June 1995. The area was flown as part of the Broken Hill Exploration Initiative, a National Geoscience Mapping Accord project implemented by AGSO, the New South Wales Department of Mineral Resources and the Department of Minerals and Energy South Australia. The survey was flown at an altitude of 60m above ground level along east-west flight lines spaced 100 metres apart on the Kalabity and Mulyungarie 1:100 000 Sheet areas (southern Curnamona) and 400 metres apart on the Pasmore, Benagerie and Lake Charles 1:100 000 Sheet areas (northern Curnamona). The total magnetic intensity, gamma-ray and digital elevation model data collected during the survey have been processed and are available for purchase, in both digital (point located data and gridded) and map form, from the Australian Geological Survey Organisation. Colour and greyscale pixel image maps are also available.

  • No abstract available