The north-eastern margin of the Gawler Craton is prospective for Mesoproterozoic iron oxide - associated copper-gold (IOCG) style mineralisation, but the considerable depth to crystalline basement, combined with the presence of an artesian Mesozoic aquifer, considerably increases expense and risk for mineral exploration. Between William Creek and Oodnadatta are a number of Proterozoic inliers surrounded by Cainozoic and Mesozoic sediments. Neoproterozoic rocks of the Adelaide Geosyncline predominate within these inliers, but older Proterozoic crystalline basement is also present, although exposures are limited. Airborne magnetic data indicate that concealed basement units are much more extensive eastwards towards Lake Eyre. Geological units within the Peake and Denison Inliers have been previously correlated stratigraphically with formations on eastern Eyre Peninsula, while similarities also exist with the geological, tectonic and metallogenic evolution of the Mount Isa Inlier in Queensland. The Mount Isa Inlier and McArthur Basin in northern Australia form one of the most significant mineralised Proterozoic provinces in the world, and contain numerous major Pb+Zn+Ag+Cu and Cu+Au deposits (e.g. Mount Isa, McArthur River, Century, Cannington, Osborne and Ernest-Henry). Close relationships exist between mineralisation, major faults and fractures, Fe metasomatism and felsic plutonism at ~1520-1490 Ma. In view of the attractive regional potential for finding economic IOCG mineral deposits, the subject PACE Initiative Year 5 Project DPY5-33 targeted an exceptionally large (~20 mGal amplitude), previously undrilled arcuate positive Bouguer gravity anomaly which extends for ~15 km, is ~2.5 km wide, and which lies close to, though not coincident with, some modest magnetic anomalies. This geophysical feature has long been recognised to exist under >200 m depth of Mesozoic cover on the north-eastern margin of the Gawler Craton, and falls on EL 3446 located west of Lake Eyre and 35 km north-east of William Creek, where Minotaur Exploration Ltd is now exploring under an Option Agreement made with licensee Rio Tinto Exploration Pty Ltd. During May-June 2009, as DPY5-33 programme operator, Minotaur successfully completed a single vertical HQ/NQ cored diamond drillhole DC09D01 to 618.8 m total depth (including 400.75 m of rotary mud precollaring through the Great Artesian Basin aquifer sequence), after reaching the crystalline basement at 395 m depth and then penetrating 224 m into basement rocks that comprise a sequence of compositionally interlayered amphibolite-facies metasedimentary paragneisses. The three predominant interlayered lithologies are a hornblende-rich mafic gneiss, a pink siliceous gneiss and a quartz+feldspar+biotite gneiss, which are thought to represent, respectively, former calcareous, siliceous and psammopelitic units. They dip at 45-60 degrees and are interpreted to be stratigraphically equivalent to isolated exposures mapped near Spring Hill (north of Douglas Creek), which have an isotopic age of ~1750 Ma (Rogers and Freeman, 1996). Numerous pegmatite dykes were intersected low down in the drilled basement section, but dykes of other compositions are absent. No volcanic rocks were encountered. IOCG-style alteration of the basement is very common, being characteristically amphibole and epidote alteration, but red rock and potassium feldspar alteration are also present locally. Thin veins are common, and contain mostly amphibole, with lesser haematite, magnetite, garnet, epidote, feldspar and calcite. The age for this IOCG-style alteration is not known. The alteration mineral assemblage is indicative of the passage of moderate-temperature fluids that were slightly hotter and were acting at greater crustal depths than those typically giving rise to the alteration products seen at Prominent Hill and Olympic Dam. No economic sulphide minerals were observed in the drill core, and only traces of pyrite are present. The drill programme has successfully achieved its objective, having confirmed that IOCG-style alteration contributes to the local positive residual gravity anomaly that was targeted at the western end of the Douglas Creek regional Bouguer gravity feature. Although planned density measurements of core samples have yet to be determined, the abundance of epidote as an alteration phase (SG = 3.35-3.45) and amphibole as both primary and alteration phases (SG = 3.2) suggests that the basement lithologies will have elevated densities.