oa Gawler Craton Uncovered

The 2003 Gawler Seismic Survey acquired 250 km of 60-fold, deep seismic reflection data along two intersecting lines in order to investigate the crustal structure of the eastern Gawler Craton, South Australia. Seismic reflection data processing has produced images of the crust down to the Moho, through the overlying Neoproterozoic successions, the Mesoproterozoic and Palaeoproterozoic Gawler Craton basement, and the Palaeoproterozoic to Archaean middle crust. Of particular interest is the crustal structure imaged in basement in the vicinity of the Olympic Dam Cu-U-Au deposit.

The Gawler Craton seismic data show that the Olympic Dam deposit lies between two regions of different crustal structural character. The southern half of the north-south traverse is dominated by a series of northward dipping reflectors, some of which correlate spatially with interpreted faults. The northern half of the traverse contains little evidence of this style of faulting. The seismic data show the presence of a major unconformity that extends across this part of the Gawler Craton. A cover sequence with maximum thickness in excess of 5 km lies above this unconformity.