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Boulia 1:250 000 interpreted geology

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.

Dataset citation

ANZLIC unique identifier: ANZCW0703002365

Title: Boulia 1:250 000 interpreted geology


Custodian: Geoscience Australia

Jurisdiction: Australia



This dataset is an interpretation of geology of the Boulia 1:250000 Sheet area based on airborne geophysics and gravity data, Proterozoic geology plus magnetic units in overlying cover rocks.

ANZLIC search words:

  • GEOSCIENCES Geophysics Maps

Spatial domain:

locality map

Geographic extent polygon: 139.5 -22, 141 -22, 141 -23, 139.5 -23, 139.5 -22,

Geographic bounding box:
North bounding latitude: -22 °
South bounding latitude: -23 °
East bounding longitude: 141 °
West bounding longitude: 139.5 °

Data currency

Beginning date: 1997-09-01

Ending date: 1999-06-01

Dataset status

Progress: Complete

Maintenance and update frequency: Not Known


Stored data format:
DIGITAL - ArcGIS-coverage ArcInfo coverage Universal Transverse Mercator (UTM) AGD66
Available format type:
DIGITAL - dat Data file MapInfo
DIGITAL - shp ArcView shape file ArcView
DIGITAL - ArcGIS-coverage ArcInfo coverage

Access constraints:

Licence and fee required

Free Data Download

Data quality


This map presents an interpretation of the geology of the Boulia 1:250 000 sheet area, based on airborne geophysical and gravity data.

The interpretation was produced with reference to the mapped outcrop geology from D.H.Blake, 1987 - "Geology of the Mount Isa Inlier and Environs" Bureau of Mineral Resources, Canberra ACT 1:500 000 Scale Map. This map should be inspected to gain an understanding of the geological framework used for the geophysical interpretation. The airborne geophysical data were acquired in 1997 during a survey that was part of the National Geoscience Mapping Accord. The survey was flown by AGSO along east-west lines, 400 metres apart at a nominal terrain clearance of 80 metres.

After the data were processed, the following images were generated:

Total magnetic intensity (TMI), reduced to the pole (RTP), colour

Analytic Signal of TMI

TMI (RTP), with easterly illumination, colour

First vertical derivative of TMI (RTP), greyscale

First vertical derivative of TMI (RTP), with easterly illumination, colour

Fractional vertical derivative (1.5) of TMI (RTP), greyscale

Automatic gain control of first vertical derivative of TMI (RTP), greyscale

TMI (RTP) upward continued 1000 metres, colour

Potassium (red), Thorium (green), Uranium (blue) RGB colour composite

Digital Elevation Model, with easterly illumination, colour

Bouguer gravity, colour

These images were combined with existing digital geology, topographical and borehole information in a GIS.

The interpretation of the data consisted of two phases:

Phase 1: Outlining magnetic sources.

Phase 2: Correlating known geology with geophysical responses and outlining and identification of geological units.

The images used for the interpretation and this geophysical interpretation map are available in digital format, suitable for use in most GIS applications.

Positional accuracy:

No analysis of the positional accuracy of features has been undertaken, however intuitively it is considered that about 95pc of the features are within 200 meters of their true position.

Attribute accuracy:

Polygons were given names based on geological formation names as used on the 1:500 000 geological map (Blake, D.H., 1987 "Geology of the Mount Isa Inlier and Environs" BMR, Canberra).

Moderate levels of confidence can be given to the link between this dataset and the above geological map. The confidence level of the geology map is unknown.

Logical Consistency:

The GIS package ArcInfo was used to a topological consistency check to detect flaws in the spatial data structure. This check ensured that all classified polygons are closed, nodes are formed at the intersection of lines and that here is only one label within each polygon. Where possible, geologically significant terms have been used. All data have been checked and collated to ensure consistency of naming conventions and attribute definition.


Complete geophysical data were acquired over the entire area, which were interpreted at a consistent scale. Anomalies which, based on their geophysical signature, did not have a defineable width were represented as linear features. There was no generalisation or field verification of the polygons in this dataset.

Contact information

Contact organisation: Commonwealth of Australia (Geoscience Australia) (GA)
Contact position: Manager Client Services
Mail address: Cnr Jerrabomberra Ave and Hindmarsh Dr
Mail address: GPO Box 378
Locality: Canberra
State: ACT
Country: Australia
Postcode: 2601
Telephone: 02 6249 9966
Facsimile: 02 6249 9960
Electronic mail address:

Metadata information

Metadata date: 2013-03-08

Additional metadata

Metadata reference XHTML:

Metadata reference XML:


Authors:Mackey, T.E. Gunn, P.J. Meixner, A.J. Blake, D.H.