Abstract:
I treat regions and ages with hydrocarbon potential, and ask firstly have we recognised all types of basins we should be looking for, and secondly have we found them? (i) Mid-to-late Cretaceous subduction beneath Gondwana; the accretion complex and slope basins are widely preserved, an arc remnant exists (Mt. Somers), but where are forearc and backarc basins? (ii) Tasman spreading; precursor rifting was very widespread, but we have yet to document the full extent, or to recognise patterns or analogues. Time overlaps between (i) and (ii) need to be considered. (iii) Tectonic quiescence and transgression, late Cretaceous to late Oligocene; we know about transgressive coal measures as source rocks, but how much do we know about quartz- and greensand-rich fan traps in the passive margin sequences, outer shelf sand bodies, external sea-level controls, transform-related basins and southwestern South Island, the relation of South Fiji Basin to the apparently oblique subduction at the Tonga Trench (ODP Site 841), and what was happening at the Kermadec/Colville arc? (iv) Source basin for the Tangihua/Matakaoa ophiolites; where was (is) it? Several scenarios are possible. (v) Miocene-Pliocene convergence; the system is rather completely preserved, but several things remain to be explained, such as the whereabouts of forearc basin(s), the non-recognition of back-arc basins, and the mismatch of a 25 Ma forearc in eastern North Island with a 1 to 2 Ma arc. (vi) Major Pliocene re-organisation is implied, with dextral displacement and clockwise rotation of eastern North Island along the Vening Meinesz-North Island Shear Belt, inception of the Alpine Fault sensu stricto, growth of mountains, subsidence of the South Wanganui Basin, and new forearc basins, for example.