During the period March to June 1990, 9 stratigraphic rotary mud/diamond cored holes with a total penetration of 3056 m, including 433.25 m of NQ or HQ cored diamond tails, were drilled by SADME in three cases and by its contractor Rockdril for the rest, to characterise the unknown geology of magnetic domains evident in the basement to the Murray Basin. Excepting Briaken Park 1, where drilling ceased while within a deep trough filled by Permian sediments, the other eight holes were successfully terminated within the targeted Early Palaeozoic basement metasedimentary or igneous rocks. Basement lithologies intersected were : - limestone-shale-basalt (Peebinga 1), which may represent either Normanville Group Fork Tree Limestone - Truro Volcanics, or a correlative of the Mount Stavely Volcanic Complex; - ?metadoleritic amphibolite (Wynarka 1 and 2, Caringa 1) and metadolerite intruding rhyolitic albitite (Peake 1), both being correlated with amphibolites intruding Kanmantoo Group sediments in the eastern Mount Lofty Ranges; - meta-arkose (Kringin 1), correlated with Kanmantoo Group sediments; - post-Delamerian Orogeny granite to granodiorite (Wirha South 1, Tori Hills 1). Although their base and precious metal values were low, all of the mafic and associated sedimentary sequences contained abundant sulphide mineralisation (up to 5%) as pyrite. None of the MBT drillholes encountered Cretaceous or Devonian rocks. Only Peebinga 1 and Briaken Park 1 intersected rocks of the Permian glacigene Urana Formation. In conjunction with conclusions drawn from assessments of previous drilling records and the recent geophysical interpretation, three areally extensive provinces of mafic and/or bimodal volcanic and intrusive rocks, having inferred considerable potential for stratiform volcanogenic and epithermal feeder-style base metal mineralisation, were delineated by the subject drillholes. Potential for gold and platinum-group mineralisation to occur in the Early Palaeozoic basement is also considered as high.