Geochronology of the Gawler Craton, South Australia

Since 1969, a major geochronological investigation has been carried out by the South Australian Department of Mines and Energy on rocks of the Gawler Craton. Isotopic dates define three broad groupings corresponding to the Sleafordian Orogeny 2500–2300 Ma, the Kimba Orogeny 1820–1580 Ma, and the Wartakan Event 1580–1400 Ma. The oldest rocks in the craton belong to the Mulgathing Complex (in the north) and the Sleaford Complex (in the south). They consist of strongly folded and metamorphosed paragneisses (probably sediments and volcanics) intruded by several granites during the Sleafordian Orogeny. The Sleafordian Orogeny was followed by a 500 Ma period of magmatic and tectonic quiescence prior to the Kimban Orogeny. During that time sediments of the Hutchison Group were deposited. The Kimban Orogeny is characterized by complex deformation, high‐grade metamorphism and multiple synorogenic granite intrusion. It concluded at ca. 1580 Ma, but was followed by postorogenic acidic magmatism, sedimentation and minor deformation (the Wartakan Event). The spectrum of isotopic dates ends at ca. 1400 Ma, the approximate time of cratonization of the Gawler Craton.