Taranaki Basin

[5] The basin is divided into two main components, the Western Platform and Eastern Mobile Belt, formerly known as the Taranaki Graben.

The Eastern Mobile Belt extends from this fault zone to the north-south trending Taranaki fault zone, which is adjacent to the a large upthrust basement block that divides the Taranaki Basin from the later-formed, eastward Wanganui Basin.

[11] Formation of the Taranaki Basin initiated in the Late Cretaceous, due to the separation of Australia and Zealandia during the breakup of Gondwanaland.

[1][4][12] Syn-rift sediments were deposited within rift controlled grabens across the basin, and are separated from the basement rock by a regional unconformity.

[5] After the end of extension in the Late Cretaceous, the Taranaki Basin became a passive margin setting, with drift resulting in marine transgression.

[2] During drift, a decline in sediment deposition occurred, with a thinning of layers from the Cretaceous to the Eocene.

[1] The Pakawau group contains the oldest sediment within the Taranaki Basin, deposited between the Late Cretaceous and Paleocene.

The Kaimiro Formation (55-45 Ma) contains mostly poor to moderately sorted alluvial and coastal plain sandstones with some inter-bedded micaceous and carbonaceous mudstones and siltstones.

[13] The Mahoenui Group consists of calcareous mudstones, with thinly interbedded sandstones, siltstones, and limestones.

[7] A wide variety of petroleum play types, mostly structural, can be seen throughout the basin due to its complex history.

The main trap styles found within the basin are fault-dependent closures, inversion anticlines, and overthrusts.

[5] The majority of oil produced from the Taranaki basement are sourced from coals and marine shales from the Late Cretaceous and Paleogene.