Abstract:
This thesis is an account of the stratigraphy, biostratigraphy, palaeontology and structure of the Upper Miocene to Pleistocene sediments of an area east of Gladstone in the Wairarape District.
The geology of the area was described by McBeath (1950) and McGill (1956), and the Pleistocene cyclothem sequences by Vella (1963b).
The Cretaceous indurated mudstones and greywacke are noted and are divided into two groups. The Upper Tertiary siltstones and mudstones are subdivided into the Hurupi Formation of Waiauan or possibly greater age, followed by the Wairarapa Formation mainly mudstone and of Tongaporutuan to Waitotaran age. The Quaternary rocks consist of two cyclothem sequences of Hautawan and Lower Nukumaruan age overlain by shallow water deposits of and possibly Okehuan or younger sediments. The Hawera and Recent Series are represented by high terrace and low terrace deposits and alluvium.
Folds and faults of the eastern and western areas are briefly described, and the structural developments are outlined.
The biostratigraphic zones and depth biofacies of Foraminifera were studied in five stratigraphic sections in the Wainuioru River Valley.
Five Foraminiferal zones are recognised and are correlated with the Waiauan, Lower, Middle and Upper Tongaporutuan, and Opoitian stages and substages. Attention is drawn to the poor definition of the Kapitean and Waipipian stages. No major lithologic break is obvious suggesting that previous record of non-deposition of the Kapitean and Opoitian sediments is invalid.
In the final section depth biofacies of Foraminifera are determined. Increasing depths of deposition is recognized from Middle Miocene to Upper Miocene and Upper Pliocene, Depths then gradually decreased to the end of Pliocene followed by oscillation of depths forming the Lower Pleistocene cyclothem sequences.
