Abstract Reconnaissance 2D seismic reflection data intended to investigate the petroleum potential of New Zealand’s marine territories have contributed many insights into the geological evolution of the large continental block that surrounds New Zealand. These include: definition of a back-thrust system to the Mesozoic Gondwana subduction margin along the Northland–Reinga Basin and the transition to back-arc rifting; the development of a Mesozoic back-arc rift system through the present New Caledonia and probably the Bounty troughs; the Early Cretaceous cause, at least locally, of the cessation of subduction along the New Zealand sector of the Gondwana margin; evidence for anticlockwise rotation of eastern New Zealand relative to the west in Late Eocene time; an explanation for the development of the Alpine Fault and the South Island compressional strike-slip margin between the Pacific and Australian plates through South Island.

Abstract The New Zealand Exclusive Economic Zone (EEZ) contains at least six large deep water basins: the deep water Taranaki basin, the Raukumara basin, the Pegasus basin, the Head of the Bounty trough, the Great South basin and the Solander trough. Structural styles vary from rift basins through strike-slip dominated basins to major accretionary prisms. Source rocks encountered include coal measures, black marine shales, and lacustrine facies. Sedimentary thicknesses, heat flow studies, and basin modeling supported by production and numerous seeps in the shelf and onshore, suggest that these basins may be prolific hydrocarbon producers in the future. Recent developments suggest that the most promising of these basins is the deep water Taranaki basin, outboard of New Zealand’s only producing basin to date. The petroleum histories of most of these basins began with the Late Cretaceous break-up of Gondwana and the formation of rift basins. In onshore New Zealand and on the continental shelf, many of the source rocks for the productive Taranaki basin were deposited at this time. The earliest sediments to be deposited were commonly fluvial, lacustrine, deltaic and nearshore facies followed by an increasing marine influence as the region foundered through the Paleogene. The Neogene saw the formation of the present plate boundary and the emergence of New Zealand in response to plate collision. Many of the more spectacular structures in the New Zealand sedimentary basins were formed during the Neogene. Meanwhile, the deep water basins away from the plate margin continued a quieter development. Some inversion occurred, but not to the extent of the nearshore and onshore regions. This relatively gentle structural evolution increased the likelihood of discovering large hydrocarbon fields in unbreached structural traps.