The Geological Survey of South Australia, in partnership with Geoscience Australia, is undertaking a regional pre-competitive geoscience research drilling program in the far west of South Australia called the Coompana Drilling Project. The Coompana Province, located between the western Gawler Craton to the east, the Musgrave Province to the north and the Madura Province to the west, is one of the least understood and explored geological provinces remaining on the Australian continent. Bedrock in the region is completely covered by Neoproterozoic to Cenozoic sediments, and there are no known basement exposures. Up to 18 new drillholes were planned as part of this project to intersect as many of the different geophysical domains as possible, as delineated from the recently acquired Coompana airborne magnetic/radiometric survey and the Coompana regional gravity survey. The primary objective of the Coompana Drilling Project is to obtain high quality drill core samples from the untested basement units beneath the Nullarbor Plain. The outcome of the Coompana Drilling Project will be to provide our stakeholders with new pre-competitive data and a geological framework that more clearly defines the geology and prospectivity in this region. This report provides the first release of the preliminary data collected on-site during the drilling of drillhole CDP004. This compilation includes well completion information, location and site access data, results of pre-drilling cover geophysics and depth estimates as well as the field geological logs and acquired down-hole geophysical data. The basement rock seen in the drill core of CDP004 has common igneous textures, and the layering is often defined by variations in grain size and proportions of the minerals. There are considerable compositional and textural ranges, i.e. from dioritic to granite. The rock contains common schollen, which are back-veined by leucosomes. Overall, the rock looks like migmatite, but appears to be dominated by igneous textures and consequently magmatic-state processes, and may be more diatexitic than metatexitic. In places, the rock looks like a dirty granite, suggesting that the network of the migmatite is breaking down, and the magma is flowing and starting to homogenise to form the granite and monzogranite. In particular, the granite preserves a range of textures that support the interpretation that it is transitional to the diatexite. Furthermore, there are no, or few, augen-like or solid-state recrystallisation textures, as were seen in CDP001, which would indicate a metamorphosed granite dominated by plastic deformation.