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Metadata : Northern Territory Statewide Geophysics - Radiometrics |
Index:
Metadata Details:
Name:AS/NZS ISO 19115 Geographic Information - Metadata, ANZLIC Metadata Profile
Version:1.0
Date Metadata Extracted:2025-06-17
Date Metadata Last Updated:2019-11-19
Current URL (HTML format) : http://www.ntlis.nt.gov.au/metadata/export_data?type=html&metadata_id=FAD59DC9DAF0AEF4E040CD9B2144730C
Current URL (XML format) : http://www.ntlis.nt.gov.au/metadata/export_data?type=xml&metadata_id=FAD59DC9DAF0AEF4E040CD9B2144730C
Citation
ANZLIC Identifier:FAD59DC9DAF0AEF4E040CD9B2144730C
Title: Northern Territory Statewide Geophysics - Radiometrics
Citation Date:1980-12-31
Date Type:creation
Custodian:Department of Industry, Tourism and Trade
Description
On a background of pre-1980 GA-collected magnetic and radiometric data, further airborne surveys by NTGS and exploration companies have been gridded, merged and imaged on the NT-wide scale. Grids and images are supplied on disk freely to the public, the images are served over the Internet through the Image Web Server and STRIKE, the NTGS' Internet GIS.
- geoscientificInformation
Bounding Coordinates:
- North Bounding Coordinate:-11
- South Bounding Coordinate:-26
- East Bounding Coordinate:138
- West Bounding Coordinate:129
Dataset Status
Dataset ID:
Language:English
Character Set: Latin 1
Progress:completed
Maintenance and Update Frequency:annually
Data Currency Start Date:1980-01-01
Data Currency End Date:
Access Constraint:Copyright Northern Territory of Australia (Northern Territory Geological Survey) 2018
With the exception of the Northern Territory of Australia logo, other government and corporate logos and where otherwise noted, all material in this publication is provided under a Creative Commons Attribution 4.0 International licence (creativecommons.org/licenses/by/4.0/legalcode).
You are free to re-use the work under the licence, on the condition that you attribute the Northern Territory of Australia (Northern Territory Geological Survey) and comply with the other licence terms.
Disclaimer: While all care has been taken to ensure that information contained in this publication is true and correct at the time of publication, changes in circumstances after the time of publication may impact on the accuracy of its information. The Northern Territory of Australia gives no warranty or assurance, and makes no representation as to the accuracy of any information or advice contained in this publication, or that it is suitable for your intended use. You should not rely upon information in this publication for the purpose of making any serious business or investment decisions without obtaining independent and/or professional advice in relation to your particular situation. The Northern Territory of Australia disclaims any liability or responsibility or duty of care towards any person for loss or damage caused by any use of, or reliance on the information contained in this publication.
Data Quality
Lineage:Airborne surveys were flown in the 1960s 70s and 80s using NaI spectrometers to distinguish the gamma rays from potassium, and uranium and thorium daughters. Calibration of the aircraft system did not come routine until the 1990s, after which time measurements in counts per second was superseded by the data levels to parts per million of equivalent uranium and thorium, and percent potassium. See the Image Web Server for the metadata for the separate surveys.
Data is processed within NTGS to produce NT-wide geophysical grids and images. During stitching of the grids, calibrations from modern surveys are propagated across the older data. Grids and images are periodically updated and re-processed with the inclusion of new surveys.
Initial products are the TC, K, Th, U grids and their pseudocolor images . Images are prepared for mapping rather than exploring extremes, so the highest counts are restrained using an arctan transform. Users seeking extreme radiometrics values should refer to the line data of the relevant survey. A conventional ternary image with potassium, thorium and uranium assigned to the red, green and blue colours respectively, is provided on the Image Web Server.
Valuable as a soil map and for mapping the regolith is a specialty of the NTGS, the combined radiometrics image. The combined radiometrics (KThUTC) image uses high-passed grids of potassium, thorium and uranium as the red, green, blue hues, with a high-passed version of the total count controlling the intensity.
Positional Accuracy:Reconnaissance data collected by BMR in the 60s and 70s appears to have been located on air photos, thus accurate to better than a kilometre, whereas the higher resolution (500 m) surveys of the 70s and 80s were located by radio beacons on the ground so are accurate to 100 m approx. Since 1996 GPS located the aircraft to accuracies of a few metres, well within the footprint of the gamma ray spectrometer of approx 150 m. See the separate surveys for details.
Processing can also produce location errors, such as a half-pixel error of 50 m shifted southeast by image processing software. Gridding commonly is preceded by a light smoothing along the flight line, allowing single extreme values to appear smoothed into adjacent pixels.
Attribute Accuracy:The main source of uncertainty in the radiometric grids values is due to the propagation of calibrations into previously uncalibrated data. In the case of uranium the result is probably no better than a factor of two in the older data. Thorium, potassium and total count values are progressively more reliable, and in modern, calibrated surveys all are probably accurate to within about 10%.
Logical Consistency:Not Applicable
Completeness:Dynamic datasets. Updated annually. New images may be added.
Contacts
Name Organisation Position Role Phone Fax Manager Geoscience Business Systems Department of Industry, Tourism and Trade Manager Geoscience Business Systems custodian (08) 8999 5448 (08) 8999 6824 geoscience.spatial@nt.gov.au
Data Dictionary
No data dictionary defined for this dataset
Supplementary Information
Search Words: Geophysics, radiometrics, gamma ray, total count, potassium, thorium, uranium, regolith image, soil image.
This record maintained using the NTLIS Metadata Tool