Electromagnetic induction studies in the Eyre Peninsula, South Australia
Magnetic field fluctuations have been recorded by an array of portable three-component magnetometers at 60 sites across the Eyre Peninsula in South Australia between December 1993 and March 1995. An additional 54 magnetometer data records, collected prior to 1989 and described by Milligan (1989) and...
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1998
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fthighwire:oai:open-archive.highwire.org:gji:132/3/687 2023-05-15T13:50:44+02:00 Electromagnetic induction studies in the Eyre Peninsula, South Australia Kusi, Robert White, Antony Heinson, Graham Milligan, Peter 1998-03-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/132/3/687 https://doi.org/10.1046/j.1365-246X.1998.00478.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/132/3/687 http://dx.doi.org/10.1046/j.1365-246X.1998.00478.x Copyright (C) 1998, Oxford University Press Articles TEXT 1998 fthighwire https://doi.org/10.1046/j.1365-246X.1998.00478.x 2015-02-28T21:37:09Z Magnetic field fluctuations have been recorded by an array of portable three-component magnetometers at 60 sites across the Eyre Peninsula in South Australia between December 1993 and March 1995. An additional 54 magnetometer data records, collected prior to 1989 and described by Milligan (1989) and Milligan, White & Chamalaun (1989), were included in the analysis. A major conductive feature in the crust, first noted by White & Milligan (1984) as the Eyre Peninsula Anomaly (EPA), is re-examined to assess its continuity to the north of the original arrays and to investigate its relationship with major tectonic features. Magnetic-field time-series were converted to induction arrows in the frequency domain. These induction arrows were initially inverted using the minimum-structure 2-D Occam approach to estimate the electrical conductance of the crust. Following this, thin-sheet forward modelling was used to examine the relationship between the conductance and the dominant tectonic features. The principal results of the modelling are that a narrow conductive feature extends inland from the coast about 160 km before terminating, and the conductance is in the range 3000 to 10 000 S, which decreases inland. A strong correlation exists between the electrical conductance of the Eyre Peninsula and Bouguer gravity anomalies, and in particular the EPA is coincident with a significant Bouguer gravity gradient. There is also good agreement between the locations of the foci of earthquakes of magnitude greater than 4.0 and the EPA. We believe that the anomaly is associated with a geological fracture in the Precambrian upper crust as a result of crustal extension prior to the rifting of Australia from Antarctica in the Jurassic (160 Ma). Text Antarc* Antarctica HighWire Press (Stanford University) Geophysical Journal International 132 3 687 700 |
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Articles Kusi, Robert White, Antony Heinson, Graham Milligan, Peter Electromagnetic induction studies in the Eyre Peninsula, South Australia |
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Articles |
description |
Magnetic field fluctuations have been recorded by an array of portable three-component magnetometers at 60 sites across the Eyre Peninsula in South Australia between December 1993 and March 1995. An additional 54 magnetometer data records, collected prior to 1989 and described by Milligan (1989) and Milligan, White & Chamalaun (1989), were included in the analysis. A major conductive feature in the crust, first noted by White & Milligan (1984) as the Eyre Peninsula Anomaly (EPA), is re-examined to assess its continuity to the north of the original arrays and to investigate its relationship with major tectonic features. Magnetic-field time-series were converted to induction arrows in the frequency domain. These induction arrows were initially inverted using the minimum-structure 2-D Occam approach to estimate the electrical conductance of the crust. Following this, thin-sheet forward modelling was used to examine the relationship between the conductance and the dominant tectonic features. The principal results of the modelling are that a narrow conductive feature extends inland from the coast about 160 km before terminating, and the conductance is in the range 3000 to 10 000 S, which decreases inland. A strong correlation exists between the electrical conductance of the Eyre Peninsula and Bouguer gravity anomalies, and in particular the EPA is coincident with a significant Bouguer gravity gradient. There is also good agreement between the locations of the foci of earthquakes of magnitude greater than 4.0 and the EPA. We believe that the anomaly is associated with a geological fracture in the Precambrian upper crust as a result of crustal extension prior to the rifting of Australia from Antarctica in the Jurassic (160 Ma). |
format |
Text |
author |
Kusi, Robert White, Antony Heinson, Graham Milligan, Peter |
author_facet |
Kusi, Robert White, Antony Heinson, Graham Milligan, Peter |
author_sort |
Kusi, Robert |
title |
Electromagnetic induction studies in the Eyre Peninsula, South Australia |
title_short |
Electromagnetic induction studies in the Eyre Peninsula, South Australia |
title_full |
Electromagnetic induction studies in the Eyre Peninsula, South Australia |
title_fullStr |
Electromagnetic induction studies in the Eyre Peninsula, South Australia |
title_full_unstemmed |
Electromagnetic induction studies in the Eyre Peninsula, South Australia |
title_sort |
electromagnetic induction studies in the eyre peninsula, south australia |
publisher |
Oxford University Press |
publishDate |
1998 |
url |
http://gji.oxfordjournals.org/cgi/content/short/132/3/687 https://doi.org/10.1046/j.1365-246X.1998.00478.x |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/132/3/687 http://dx.doi.org/10.1046/j.1365-246X.1998.00478.x |
op_rights |
Copyright (C) 1998, Oxford University Press |
op_doi |
https://doi.org/10.1046/j.1365-246X.1998.00478.x |
container_title |
Geophysical Journal International |
container_volume |
132 |
container_issue |
3 |
container_start_page |
687 |
op_container_end_page |
700 |
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1766253962815602688 |