Cretaceous stratigraphy of Raukumara Peninsula

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Mazengarb, C. 1993 Cretaceous stratigraphy of Raukumara Peninsula. Lower Hutt: Institute of Geological & Nuclear Sciences Institute of Geological & Nuclear Sciences science report 93/20 51 p.


Abstract: This report summarises the stratigraphy of the mid- to late-Cretaceous strata of Raukumara Peninsula. The systematic descriptions of existing and new stratigraphic units are outlined, including comments on age, stratigraphic relationships, provenance, and depositional environments. Five fault-bounded stratigraphic-structural domains are recognised for pre-Tinui Group rocks, each with unique geological history. The Western Subbelt contains three domains (DI-D3) comprising Matawai Group rocks. The basal relationship with older basement rocks varies within each domain. The Eastern Subbelt contains Ruatoria Group rocks (D4) and Matakaoa Volcanic Group (D5). In simplistic terms, shallow water transgressive deposits occur in the western part (basal sandstones, conglomerates, and an olistostrome) overlain by shelf mudstones. Shelf mudstones predominate further east, while submarine fan sequences dominated by turbidite deposits dominate further east again. Submarine volcanics comprise the eastern-most area. (auth)