Grosjean, E., Jarrett, A.J.M., Boreham, C.J., Wang, L., Johnson, L., Hope, J.M., Ranasinghe, P., Brocks, J.J., Bailey, A.H.E., Butcher, G.A., and Carson, C.J.
• Hydrocarbon and mineral potential of the Carrara depocentre in the South Nicholson region, Australia, were investigated. • Cambrian rocks from the NDI Carrara 1 well have good oil source potential. • Black shales at the top of the Proterozoic section have potential for generating gas. • A thick interval in the Proterozoic section is identified as a shale gas resource system. • Disseminated occurrences of metal sulfides provide hints of mineralisation in the drill hole. A comprehensive geochemical program was carried out on rock samples collected in the NDI Carrara 1 drill hole, the first stratigraphic test of the newly discovered Carrara Sub-basin located in the South Nicholson region of northern Australia. The drill hole recovered continuous core from 284 m to total depth at 1750 m and intersected approximately 1120 m of Proterozoic sedimentary rocks, unconformably overlain by 630 m of Cambrian Georgina Basin carbonate-rich rocks. Total organic carbon (TOC) contents from Rock-Eval pyrolysis highlight the potential for several thick black shales to be a source of petroleum for conventional and unconventional plays. Cambrian rocks contain an organic-rich section with TOC contents of up to 4.7 wt.% and excellent oil-generating potential. The Proterozoic section is overmature for oil generation but mature for gas generation, with potential for generating gas in carbonaceous mudstones showing TOC contents up to 5.5 wt.% between 680 and 725 m depth. A sustained release of methane (up to 2%) recorded during drilling from 1150 to 1500 m suggests potential for an unconventional gas system in the Proterozoic rocks from 950 to 1415 m depth, which exhibit favourable organic richness and thermal maturity. The Proterozoic rocks, which are comparable in age to the sediment-hosted deposits of the Century Mine, contain local occurrences of lead, zinc and copper sulfide minerals providing hints of mineralisation. The combined geochemical results offer the promise of a potential new resource province in northern Australia. [ABSTRACT FROM AUTHOR]