Radiometric Grid of Australia (Radmap) v4 2019 filtered ppm thorium

Brief description

This record was harvested by RDA at 2025-03-05T09:51:51.968+11:00 from NCI's Data Catalogue where it was last modified at 2018-04-20T05:51:55.

Full description

The filtered thorium grid is a derivative of the 2019 radiometric or gamma-ray grid of Australia. The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data are collected on airborne geophysical surveys conducted by Commonwealth, State and Northern Territory Governments and the private sector. The 2019 filtered thorium grid was derived by seamlessly merging over 600 airborne gamma-ray spectrometric surveys. The final grid has a cell size of about 100m (0.001 degrees) and shows thorium element concentrations of the Australia region. -- This record represents data published by NCI. It uses catalogue metadata modified from Geoscience Australia. See our Record Lineage Information for more details.

Lineage

The filtered thorium grid is a derivative of the 2019 radiometric or gamma-ray grid of Australia. The radiometric grid of Australia is derived by merging over 600 airborne gamma-ray spectrometric surveys by the Commonwealth, State and Territory Governments and held in the national radioelement database of Australia. The cell sizes of the original survey grids range from 50 m through 800 m, but most have a cell size of about 100 m. The original survey grids were re-levelled and then re-sampled to generate the Radiometric Map of Australia Grids with a cell size of about 100m (0.001 degrees). The data quality varies depending on the survey. The data were 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 final grid is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This filtered thorium grid was calculated by applying a 7-point, degree-3 Savitzky-Golay low pass filter (Savitzky & Golay, 1964) to each of the original survey grids prior to grid merging. Reference: Savitzky, A. and Golay, M.J.E., 1964. Smoothing and differentiation of data by simplified least squares procedures. Analytical Chemistry, 36: 1627–1639.