Australian National Gravity Tilt Grid for Geological Edge Detection

A 2019 compilation grid derived from approximately 1.8 million gravity observations, including nearly 1.4 million ground stations from the Australian National Gravity Database and supplemented by offshore data. The grid, with a cell size of 0.00417 degrees (~435m), shows the tilt of de-trended global isostatic residual anomalies over Australia and its margins. It was produced by Geoscience Australia from data acquired by government, industry, and research entities from the 1940s onward.

Use Cases

• Detect edges of geological units by analyzing the tilt filter ratio derived from the DGIR grid.
• Model subsurface density variations by interpreting the de-trended global isostatic residual (DGIR) anomalies.
• Integrate ground gravity station data (spaced 1-11 km) with marine data for continental-scale geophysical analysis.
• Apply the tilt grid to constrain 3D geological models in regions with 2.5 to 7 km station spacing.

Strengths

• Derived from a large base of approximately 1.8 million gravity observations.
• Incorporates ground data with station spacing as dense as less than 1 km in parts of the continent.
• Quality-checked by GA geophysicists and processed via standard methods to isolate the rock response.

Limitations

• Ground data temporal coverage is very broad (1940s to present), potentially introducing methodological inconsistencies over time.
• The grid is a 2019 compilation, so more recent ground observations after September 2019 are not included.
• Spatial resolution is fixed at a ~435m cell size, which may smooth over finer-scale features.

Provenance

Source

Geoscience Australia, sourced from the Australian National Gravity Database and global marine grids.

Collection Method

Processed from ground and marine gravity data using isostatic corrections and a Fast Fourier Transform (FFT) to calculate a tilt filter.

Time Range

Underlying ground observations collected from the 1940s to 2019.

Freshness

Dataset metadata last updated in April 2026, but the underlying gravity observation compilation is from September 2019.

Geography

Australia and its continental margins.