Biostratigraphic revision of Maui-2 offshore well south Taranaki Basin

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Scott, G.H. 1985 Biostratigraphic revision of Maui-2 offshore well south Taranaki Basin. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report PAL 99. 47 p.

Abstract: A revision of the biostratigraphy of Maui-2 offshore well is presented, based on material originally prepared by Shell BP Todd Oil Services Ltd.Pliocene assemblages occur between 375 m and c. 715 m. The base of the Mangapipian Stage is placed at c. 470 m; Waipipian extends between c.475-c.535 m followed by Opoitian (?and upper Kapitean). Shallow shelf environments occurred in the Mangapipian, deepened to outer shelf in the Waipipian and upper Opoitian, and then shallowed again.Miocene strata extend between c.715-c.990 m. Lower Kapitean is recognized between c.715-c.990 m; upper Tongaporutuan between c.90-c.1145 m and lower Tongaporutuan between c.1145-1645 m. The site deepened progressively in this period, with outer shelf-upper bathyal taxa present in the lower Tongaporutuan. Waiauan strat occur between c.1645-1800 m, Lillburnian between c.1800-c.2320 m, Clifdenian between 2.2320-c.2485 m and upper Altonian between c.2485-c.2590. The Waiauan-upper Altonian represents a long period of predominantly clastic sedimentation at bathyal depths at a site with good oceanic circulation.Lower Altonian and Otaian strata were not identified and a diastem, or condensed sequence, seems to occur in the upper argillaceous member and the middle chalky member of the Takaka-Te Kuiti Formation. It separates middle Altonian strat from Waitakian. Waitakian extends between c.2590-c.2695 m and represents a major period of oceanic carbonate sedimentation at bathyal depths. A thin mudstone break (<4 m) at c.2672 m indicates sheltered shelf sedimentation; this unit has faunal resemblance with uppermost Kapuni Group beds and may be out of sequence. The boundary (c.2695 m) between Waitakian and Duntroonian occurs near the base of the lower, glauconitic member of the Takaka-Te Kuiti Formation. The lower beds of this unit were deposited at middle shelf depths.Upper Whaingaroan strat were not identified and there may be a diastem (or condensed sequence) about the base of the Takaka-Te Kuiti Formation. A Kaiatan assemblage, indicating a middle shelf environment, occurs 17 m below the top of the Kapuni Group at 2728 m.