Coompana Gravity Survey: download now
The PACE Copper initiative Coompana Gravity Survey provides an exciting new insight into the buried basement geology of the Coompana Province.
As 300–500 m of sedimentary cover blankets the Precambrian geology of the Coompana Province, this detailed gravity survey (Fig. 1) is key in understanding the hidden structure and compositional variations of the region.
Figure 1 Bouguer gravity image from the Coompana Gravity Survey.
Whilst major density highs and lows appear to be due to differing compositions within the basement, vertical gradient images reveal possible paleochannels or drainage features thought to be associated with the cover–basement unconformity.
A low-density response from the enigmatic Coompana Anomaly (previously defined by magnetics, e.g. Wise, Pawley and Dutch 2015), compared with high-amplitude density responses associated with similarly magnetised satellite bodies, adds to the intrigue of this frontier region.
Part of PACE Copper’s Far West Discovery Program, the survey was acquired by Atlas Geophysics between 23 January and 4 March 2017. A total of 15,498 gravity readings (13,792 individual stations) were acquired on regular grid patterns at 0.5, 1 and 2 km spacing. The survey extends from the Western Australian border well into the Gawler Craton.
Two R44 helicopters and three Scintrex CG5 gravity meters were used, as well as the Leica Geosystems GPS1200 system for post-processed kinematic centimetre level positional accuracy.
The gravity data is available to download via SARIG. Click on the ‘Spatial Search’ option, select ‘Geophysical data’ from the dropdown menu and ‘Draw Area’ before drawing a box around the Coompana area. Then click on ‘Advanced search’ and follow the prompts to download the gravity ASCII data (or grid). The survey, designated as 2017A1 in the SA Geodata database, will be incorporated into an updated statewide Bouguer gravity image to be released in the final quarter of 2017.
–Philip Heath and Tom Wise