1. Australian Government
Geoscience Australia
The 5th Edition of the Magnetic Anomaly Map of Australia, constrained by an independent dataset
Peter R. Milligan,
Brian Minty, Murray Richardson, Peter Percival, Ross Franklin
Continental Geophysics Project
Onshore Energy and Minerals Division
Geoscience Australia
Acknowledge co-authors as members of the Continental Geophysics Project.

2. Australian Government Onshore Energy Security Program (2006-2011)
Acknowledgements
Australian Government Onshore Energy Security Program ( )
Continental Geophysics Project of Geoscience Australia
Geomagnetism Project of Geoscience Australia for magnetic observatory data
Geodynamics Framework Project of Geoscience Australia
States and Territory Geological Surveys for airborne survey data
UTS Geophysics ― acquisition of AWAGS data under contract
Intrepid Geophysics – processing software
Funding approved in 2006 – a plan was already in place for an Australia-wide survey.

3. Introduction – evolution of Magnetic Anomaly Map of Australia
Contents
Introduction – evolution of Magnetic Anomaly Map of Australia
National Airborne Geophysical Database
Australia-wide airborne magnetic calibration survey (AWAGS)
Comparison of AWAGS data with airborne grid data
Future developments
Examples of use within Geoscience Australia projects
Summary
Outline of talk

4. 1. Introduction 1st Edition, 1993 2nd Edition, 1996 3rd Edition, 1999
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania
3rd Edition, 1999
4th Edition, 2004

5. 1. Introduction
5th Edition of Magnetic Anomaly Map of Australia was released in March 2010
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

6. 5th Edition Magnetic Anomaly Map of Australia
1. Introduction
5th Edition Magnetic Anomaly Map of Australia
Specifications
Grid cell spacing 3 seconds of arc (~80 m)
8.3 GBytes in 4 byte real ERMapper format
41,876 rows and 50,592 columns
Only airborne-derived TMI data for onshore & near-offshore continental areas
Underpinned by a database of matched TMI grids
Updated method of matching the individual survey grids
795 individual grids matched & merged into the composite
Resolution of each grid optimal for the specifications of source line data
27,000,000 line-kilometres of survey line data
8,000,000 line-km more than the 4th Edition in 2004
Independent AWAGS data used to constrain intermediate wavelengths
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

7. 4,200 km
1. Introduction
High resolution
20 km

8. 2. National Airborne Geophysical Database
60 years of Australian airborne magnetic acquisition by Commonwealth Government and States, Territory
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

9. 2. National Airborne Geophysical Database
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

10. GADDS – Geophysical Archive Data Delivery System
2. National Airborne Geophysical Database
GADDS – Geophysical Archive Data Delivery System
47,000 requests for data
2.3 TB of zipped data delivered
130,000 separate datasets
7,200 unique clients (14% increase from 09)
Total download volume per month (MB)
1st Edition Radiometric Map released
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

11. Survey line spacings 2. National Airborne Geophysical Database
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

12. 2. National Airborne Geophysical Database
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania

13. Height (metres) above ground surface
2. National Airborne Geophysical Database
60 m
80 m
100 m
150 m
≥300m
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania
Height (metres) above ground surface

14. ~ 800 surveys are merged using statistics of boundary overlaps
2. National Airborne Geophysical Database
The latest index map of airborne survey line-spacings across Australia. Most modern data is acquired at a ground elevation of 100 m or less.
Red is line spacing <= 500 m
Purple is 2008/2009 acquisition by states and GA
Pink is 800 m line spacing
Light blue >= 3200 m
Intermediate blue 3000 to 3200 m
Dark blue usually 1500 to 1600 m
Point out the excellent continental coverage, and the on-going acquisition program by the States, particularly recent off-shore coverage near Victoria and Tasmania
400 km
~ 800 surveys are merged using statistics of boundary overlaps

15. 3. Australia-wide Airborne Geophysical Survey (AWAGS)
Data acquired as part of the Australian Government’s Onshore Energy Security Program in 2007
Line spacing 75 km
The AWAGS Project
The Australia-wide Airborne Geophysical Survey (AWAGS) project acquired both total-field magnetic and gamma-ray spectrometric data across Australia in 2007, with N-S lines spaced 75 km apart, E-W ties spaced 400 km apart (along the 1:1m map sheet boundaries), and 80 m nominal terrain clearance.
The survey was carefully designed so that the minimum length of 400 km for all lines enables the intermediate crustal wavelengths across Australia to be measured. However, accurate spatial crustal magnetic data depend upon accurate removal of time variations of the Earth’s magnetic field, which occur with a continuous spectrum from very short (fractions of a second) (pulsations) to very long (daily variation) periods, and also vary in space, due to both source-field effects and induction effects..
These time variations were recorded at pairs of ground sites, concurrently with the airborne acquisition, and supplemented by geomagnetic observatory and other data.
Point out the coloured 1:1m acquisition areas, the observatories and base-stations. 2 N-S lines per 1: map sheet, which is a basic acquisition unit of the regular airborne surveys.
400 km
Long lines (> 400 km) flown N-S in 1m map sheet blocks, with two lines per 1: map sheet
“Diurnal” control from temporary ground magnetometer sites and geomagnetic observatories

16. AWAGS field acquisition
CRESCO series aircraft at Canberra Airport, range 2550 km, with Geometrics Cesium Vapour G822A magnetometer in stinger. Operated by UTS Geophysics.
Two aspects of field data acquisition. Airborne and ground. Point out the duplication of instruments to ensure against loss of data, and that it was critical that they recorded for 24 hours per day, so that the midnight quiet values could be measured, when the time-varying current effects are minimal.
Ground magnetometers at Grafton airport. Geometrix 856AX proton, Scintrex Envimag proton and Bartington 3-component fluxgate.

17. 5. Derivative Products Variable RTP Half VD Tilt derivative
Analytic Signal

18. 6. Examples
Onshore Energy Security Program ( ) Geodynamic Framework Project areas

19. Inversion results coarse 3D map inversion
6. Examples
Northwest Queensland (Chopping et al.)
Inversion results coarse 3D map inversion

20. Inversion results coarse 3D map inversion: slice at 2 km depth
6. Examples
Inversion results coarse 3D map inversion: slice at 2 km depth

21. Inversion results coarse 3D map inversion: slice at 30 km depth
6. Examples
Inversion results coarse 3D map inversion: slice at 30 km depth

22. 6. Examples

23. 6. Examples
Uninterpreted (middle) and interpreted (upper) versions of North Queensland deep seismic reflection line 07GA-IG1, and the magnetotelluric model for the line (lower panel).

24. National Maps and Data Standards Project
6. Examples
Mapping under cover of the Davenport Province ( Ma), Northern Territory, using half vertical derivative reduced to the pole (Stewart, 2011)
National Maps and Data Standards Project
Trebles the known size
150 km

25. 6. Examples
Depth to magnetic basement of the Gawler-Curnamona region, South Australia (Meixner, 2010)

26. Shallow Crustal Elements based on National Magnetics Grid
6. Examples
Major
Crustal
Divisions
Shallow Crustal Elements based on National Magnetics Grid
Map of Australian Crustal Elements (Shaw, 1995)

27. 7. Summary
The 5th Edition of the Magnetic Anomaly Map of Australia released in 2010
A method has been developed for the removal of time variations from AWAGS calibration survey data
AWAGS data provides a reference data set to constrain intermediate wavelengths of the magnetic field across Australia
A suite of derivative products is being developed for release
Data available from gadds download site: