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Jackson, WA interpreted geologyNote: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2. Dataset citationANZLIC unique identifier: ANZCW0703002687 Title: Jackson, WA interpreted geology CustodianCustodian: Geoscience Australia Jurisdiction: Australia DescriptionAbstract: This dataset is an interpretation of geology of the Jackson 1:250000 Sheet area based on airborne geophysics and gravity data, Proterozoic geology plus magnetic units in overlying cover rocks. ANZLIC search words:
Spatial domain:
Geographic extent name: JACKSON - WA-2436 - 1:50 000 Map Series - Western Australia Geographic extent polygon: 118.5 -30, 120 -30, 120 -31, 118.5 -31, 118.5 -30, Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register
Data currencyBeginning date: 1998-07-01 Ending date: 2000-01-01 Dataset statusProgress: Complete Maintenance and update frequency: Not Known Access
Access constraints: Licence and fee required Order ProductData qualityLineage: This map presents an interpretation of the geology of the Jackson 1:250 000 sheet area, based on airborne geophysical and gravity data. The interpretation was produced with reference to the mapped outcrop geology from the 1983 "Geological Map of Jackson, W.A.", 1:250 000 scale map, Geological Survey of Western Australia. 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 along east-west lines, 400 metres apart at a nominal terrain clearance of 60 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 in a GIS. Positional accuracy: No analysis of the positional accuracy of features has been undertaken, however intuitively it is considered that about 95% 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 1983 "Geological Map of Jackson, W.A.", 1:250 000 scale map, Geological Survey of Western Australia. 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 perform 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 there 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. Completeness: 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 definable width were represented as linear features.There was no generalisation or field verification of the polygons in this dataset. Contact information
Metadata informationMetadata date: 2013-03-08 Additional metadataMetadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703002687.html Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703002687.xml The interpretation of the data consisted of two phases: Phase 1: Outlining magnetic sources. Using all of the magnetic images listed above, the sources of each magnetic anomaly were outlined. Regions of similar magnetic character and/or texture were also outlined. Linear trends in the magnetics were identified. These steps were completed from a purely geophysical perspective, without consideration of the geology, as an attempt to create an objective starting point for Phase 2. Phase 2: Correlating known geology with geophysical responses and outlining and identification of geological units. The geological units in the existing geological maps were correlated with anomalies found in the geophysical datasets, and their boundaries were modified or extended to match the geophysical responses. In some situations, especially where Phanerozoic and regolith units obscure the basement geology, distinctive geophysical anomalies were identified which do not closely relate to known geological units. In these situations boundaries of the geophysical responses were traced and identified either in terms of their possible geological source or, if this was not possible, in terms of the types of geophysical responses characterising the area. Faults, identified by the termination of the various units and termination of linear anomalies within units, were identified. Where possible, the linear features identified in Phase 1 were given geological identifications. Authors:Mackey, T. |
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