Gawler Craton Mineral Promotion Project Plan, 2000-2004

The Gawler Craton has been defined as that region of South Australia where Archaean to Mesoproterozoic crystalline basement has undergone no substantial deformation (except minor brittle faulting) since 1450 Ma (Figure 1; Thomson, 1975; Parker, 1993; Daly et al, 1998). The eastern and southeastern boundaries conventionally are defined by the Torrens Hinge Zone (THZ), although Gawler Craton basement that was deformed during the Delamerian Orogeny is known to the east of the THZ (eg Barossa Complex, Peake and Denison Inliers). The southern boundary corresponds to the inboard edge of the continental shelf. The Gawler Craton and the East Antarctic Craton are rifted segments of the Mawson Continent (Fanning et al, 1995). Western, northwestern and northern boundaries of the Gawler Craton are defined by the faulted margins of thick Neoproterozoic and younger basins. As a consequence of the extensive surficial and sedimentary basin cover, the level of understanding of the craton's geology and prospectivity are limited in comparison with most other Australian Archaean and Proterozoic cratons. Application of high-resolution regional aeromagnetic surveying during the mid-1990s (South Australian Exploration Initiative - SAEI), for the first time allowed an integrated interpretation and synthesis of the geology of the craton (Fairclough and Daly, 1995a; Fairclough and Daly, 1995b; Schwarz, 1996). A revised interpretation of the tectonic evolution of the Gawler Craton incorporating SHRIMP U-Pb geochronology, was presented by Daly et al (1998). Three principal orogenies have been proposed: The Sleafordian Orogeny (peak metamorphism at ~2420-2440 Ma), the Kimban Orogeny (KD1-KD2-KD3: 1845-1700 Ma), and the Kararan Orogeny (~1650 Ma and 1565-1540 Ma). It has been suggested that the Kararan Orogeny in the western and northern Gawler Craton represents the continental collision of the 'eastern proto-Yilgarn' and the Mawson Continent (Daly et al, 1998). The geodynamic significance of the Sleafordian and Kimban Orogenies is unclear. Subdivision of the Gawler Craton into tectonic domains has evolved as further information has become available (Figure 1; eg Parker, 1993; Flint and Parker, 1982; Drexel et al, 1993; Teasdale, 1997). In general the definition and nature of the domain boundaries are not well understood - addressing this problem is a key objective of the Gawler Craton Project. The resultant framework will be important for assessing prospectivity because the ore-forming systems are products of crustal-scale processes that may vary between tectonic domains. The contents of this GA Record were written in 2000, and were presented on the Gawler Project website prior to the publication of this GA Record.