ABSTRACT: Deep-water frontier basins of northwestern New Zealand - burial history and hydrocarbon maturation

Stagpoole, Vaughan, R. Herzer, R. Funnell, and C. Uruski , Institute of Geological and Nuclear Sciences, Lower Hutt 6009, New Zealand

Recent acquisition of seismic reflection data from the deep-water ( > 1500 m) parts of northwestern New Zealand provides critical information on the depositional history of the region. The Reinga and New Caledonia basins, along with the deep-water parts of the adjacent Taranaki and Northland basins, offer opportunities for significant discoveries. These basins cover a combined area of more than 80,000 km² and contain up to 8 km of Cretaceous and Cenozoic strata.

Correlation of seismic reflection data with horizons in the Taranaki and Northland basins suggest early rift sediments are likely to be Cretaceous terrestrial coal measures and marine units. These are overlain by Tertiary transgressive sandstones, mudstones and a condensed mid-Tertiary carbonate sequence. Neogene sediments comprise silts and muds that grade to hemipelagic drifts in distal parts of the Reinga and new Caledonia basins.

Burial history and hydrocarbon generation models, using typical source rock parameters for Cretaceous terrestrial and marine sediments in the Taranaki Basin, predict that petroleum generation has taken place over large areas, and that expulsion has occurred in the deeper sub-basins. Potential reservoirs and structural plays with significant closure have also been identified. With modern deep-water drilling technology, the frontier basins of northwestern New Zealand must now be considered as viable petroleum exploration provinces.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia