The Southern Carnarvon deep seismic reflection survey, 11GA-SC1, builds on the existing network of deep-crustal seismic surveys, and was aimed at improving the understanding of the crustal structure of Western Australia.
The survey was conducted in May–June 2011, as a joint project between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), and was funded from GA’s Onshore Energy Security Program and GSWA’s Exploration Incentive Scheme (EIS).
The main objectives of the survey were to:
- image the Southern Carnarvon Basin, particularly the Byro Sub-basin
- investigate the transition into the Yilgarn Craton
- better understand the relationships between the Pinjarra Orogen beneath the Southern Carnarvon Basin, the Gascoyne Province and the Narryer Terrane
- study the architecture of the Narryer Terrane of the Yilgarn Craton, and link to the Capricorn and Youanmi deep crustal seismic surveys
The western end of the Southern Carnarvon seismic line crosses the Woodleigh Impact Structure, and demonstrated that the structure is only about 50 km in diameter, rather than >100 km as previously thought. Farther east, the Byro Sub-basin consists of two half-grabens, about 5.5 and 7 km deep respectively. Two distinct sedimentary packages, Ordovician – Lower Devonian and Upper Carboniferous – Permian, are separated by a Late Devonian – mid-Carboniferous angular unconformity probably a far-field effect of the Alice Springs Orogeny of central Australia.
The Mesoproterozoic–Neoproterozoic Badgeradda Group can be seen beneath the eastern half-graben. At depth, major sutures dip to the west and extend to the Moho. The Narryer Terrane extends west to the Darling Fault (the western boundary of the Byro Sub-basin), beneath the Errabiddy Shear Zone.
The data have now been interpreted and the results released at a public workshop held at the department’s Perth headquarters at Mineral House in February 2013. Details are as follows:
- The extended abstract volume and accompanying material, including the PowerPoint presentations, are available for download via the links below.
- The migrated uninterpreted and interpreted seismic sections are available for download (in multiple formats) directly from Geoscience Australia.
The Youanmi seismic data is now available from Geoscience Australia. The data is available as PDF images of the migrated seismic line cross-sections, together with ArcMap GIS shapefiles of the seismic shot points and the common depth points (CDP) shown on the cross-section images.
Interpretations of the Southern Carnarvon deep crustal seismic line were released at a public workshop held at Mineral House in February 2013. This workshop also presented results for the Youanmi deep crustal seismic lines. The workshop consisted of 12 presentations and was accompanied by the release of a series of extended abstracts and geological plates. The five presentations relating to the Southern Carnarvon Basin can be viewed below.
Southern Carnarvon workshop (27 February 2013) – presentations
|Interpretation of magnetic and gravity data across the Southern Carnarvon Basin, and the Narryer and Youanmi terranes in Western Australia: multiscale edge detection (worms), forward modelling, and cross-gradient joint inversion
|Lithospheric structure in the vicinity of the SC1 and YU reflection profiles
|Geological interpretation of deep seismic reflection line 11GA-SC1: Narryer Terrane to Southern Carnarvon Basin
|Geodynamic implications of the Youanmi and Southern Carnarvon deep seismic surveys
|Acquisition and processing of the Youanmi and Southern Carnarvon seismic surveys
|Ross Costelloe and Leonie Jones