Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid  


Authors / CoAuthors

Geophysical Acquisition & Processing Section

Abstract

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 0.00083 degrees (approximately 88m).The data are in nanoTesla per metre (or nT/m). 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. This survey grid is essentially levelled to AWAGS. 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-15 geomagnetic reference model using a data representative date and elevation representative of the survey. A further enhancement has been completed to enhance the geological interpretation of the data.

Product Type

dataset

eCat Id

144747

Contact for the resource

  Point of contact

Commonwealth of Australia (Geoscience Australia)  
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia

Keywords

theme.ANZRC Fields of Research.rdf
  • EARTH SCIENCES
( Data centre )
  • NCI
( Discipline )
  • Earth sciences
( Discipline )
  • geophysics
( Feature type )
  • grid
( Place )
  • Australia
( Place )
  • None
( Project )
  • survey 1324
( Theme )
  • GADDS2.0
( Theme )
  • TMI
( Theme )
  • RTP
( Theme )
  • AWAGS
( Theme )
  • magnetics
( Theme )
  • magnetism
( Theme )
  • palaeomagnetism
( Theme )
  • airborne digital data
( Theme )
  • national
( Theme )
  • geophysical survey
( Theme )
  • mag
( Theme )
  • total magnetic intensity
( Theme )
  • reduced to the pole
( Theme )
  • grid
( Theme )
  • raster
( Theme )
  • pseudo-gravity transformation
( Theme )
  • total horizontal derivative filter
( Theme )
  • pseudo susceptibility
( Theme )
  • tilt angle
( Theme )
  • total horizontal gradient
( Theme )
  • variable vertical gradient of TMI vertical component
( Theme )
  • VBzz
  • Published_External

Publication Date

2020-11-04T00:00:00

Creation Date

2020-11-04T00:00:00

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - license

Use - license

Status

completed

Purpose

Maintenance Information

notPlanned

Topic Category

geoscientificInformation

Series Information

Lineage

This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid is an airborne-derived Total Magnetic Intensity (TMI) Reduced to the Pole (RTP) enhanced grid for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019 (Poudjom Djomani et al., 2019). The survey was acquired under the project No. 1324. The 2019 magnetic grid was derived from a complete re-levelling of the national magnetic grid database. The survey grids were levelled to each other, and to the Australia Wide Airborne Geophysical Survey (AWAGS) (Milligan et al., 2009), which serves as a baseline to constrain long wavelengths in the final grid. The levelling and grid-merging procedure was described in detail in Minty et al. (2003). The grid has a cell size of 0.00083 degrees (approximately 88m). The data are in nanoTesla per metre (or nT/m). 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-15 geomagnetic reference model using a data representative date and elevation representative of the survey. A further enhancement has been completed to enhance the geological interpretation of the data. Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014). This Index is also available online at http://pid.geoscience.gov.au/dataset/79134. References: Milligan, P.R., Minty, B.R.S., Richardson, M. & Franklin, R., 2009. The Australia-wide Airborne Geophysical Survey accurate continental magnetic coverage. Preview, No. 138, p. 1-128; Minty, B.R.S., Milligan, P.R., Luyendyk, A.P.J. and Mackey, T., 2003. Merging airborne magnetic surveys into continental-scale compilations. Geophysics, 68 (3), 988-995; Percival, P.J., 2014. Index of airborne geophysical surveys (Fourteenth Edition); Poudjom Djomani, Y., Minty, B.R.S., Hutchens, M., Lane, R.J.L. 2019, Total Magnetic Intensity (TMI) Grid of Australia 2019 - seventh edition - 80 m cell size. Geoscience Australia, Canberra. http://dx.doi.org/10.26186/5e9cf3f2c0f1d, eCat record number 131505.

Parent Information

Geophysical Data Collection - Airborne Geophysics

UUID - ddeb0fc4-32e3-4913-80f2-f4249b17a925,

eCat ID - 111301

Extents

[-43.9301, -9.0265, 105.9996, 154.6635]

Reference System

GDA94 (EPSG:4283)

Spatial Resolution

Service Information

Associations

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid NCSS    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid OPeNDAP    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid WMS    

Association Type - operatedOnBy

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid WCS    

Downloads and Links

File available for download in various formats from the GADDS2 portal  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid file download  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid NCSS  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid OPeNDAP  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid WMS  

Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid WCS  

Source Information

This Magnetic Anomaly Map of Australia, Seventh Edition, 2020 - Enhanced Products Package - vBzz (PGravTHD) grid includes airborne-derived TMI RTP enhanced data for the Magnetic Anomaly Map of Australia, Seventh Edition, 2019.