This report is the first section of the summary report on the project "Mesoproterozoic Granites in South Australia" undertaken by Drs Kathy Stewart and John Foden at the Department of Geology and Geophysics, University of Adelaide. Subsequent sections cover Mesoproterozoic granites in the Mount Painter/Mount Babbage and Olary regions. This project was undertaken under the ARC-Industry Collaborative program, with invaluable assistance provided by the industry partners of the project, BHP, MIM, North Exploration and PIRSA. Mesoproterozoic granites present on the Gawler Craton have been assigned to two main groups: - The - 1.6 Ga Hiltaba Suite, whose constituent plutons are widespread across much of the central Gawler Craton; and - The -1.5 Ga Spilsby Suite, which is limited to exposures on few islands off the eastern coast of southern Eyre Peninsula, including Spilsby Island. At the inception of the project, a reasonable amount of data existed on the Mesoproterozoic granites of the Gawler Craton, however, several problems were evident with the existing geochemical information. These problems included: • an uneven distribution of data • some older analyses did not include many of the elements now known to be vital in looking at granite genesis • with a few exceptions, most of the data was simply attributed as coming from Hiltaba granite, without further suballocation on a smaller scale. The currently reported section of the project was designed to study Mesoproterozoic granitoids that occur on the Gawler Craton. One of the reasons these granites are of significant interest is their association with known mineralisation, eg. the large Cu-Au-U-REE deposit at Olympic Dam, and Pb-Zn mineralisation at Menninnie Dam. Despite this demonstrated association of granites of Mesoproterozoic age with mineralisation, prior to the start of this project surprisingly little detailed information was known about the granites themselves, with one exception being the study of the granitoids around Olympic Dam by Creaser (1989).