Are thick volcanic piles concealed in North Australian proterozoic basins?

Abstract

Long wavelength magnetic anomalies of moderate amplitude common across large parts of northern Australia are usually assigned to deep sources beneath relatively undisturbed mid Proterozoic or Phanerozoic cover rocks. These can be shown, in the McArthur Basin at least, to be largely due to thick volcanic sequences that either do not outcrop or only outcrop in thinned, onlapped variants near the basin margins. This alternative interpretation of the basin indicates that it might have a scale and formation content comparable with that of the adjacent western Mt Isa sequence and theories about basin formation, mineralising processes and fluid circulation could be reviewed.