Geomorphologic Controls on the Evolution of Submarine Channels in the Clifdenian-Tongaporutuan Interval of the Southern Taranaki Basin, offshore New Zealand

Abstract

The Clifdenian-Tongaporutuan interval in the Southern Taranaki Basin experienced significant turbidity activities during the Middle to Late Miocene leading to formation and burial of several submarine channels. The chronologic evolution of these channels is difficult to prove because of their architectures, repeated cut- and- fill, stacking patterns, erosive nature, and spatial-temporal interactions. In this study, mega merged high-quality 3D seismic reflection data (from three seismic surveys) coupled with five exploration industrial standard wellbore data were used to analyze the geomorphologic controls on the evolution of fourteen channels within the Clifdenian-Tongaporutuan interval (Middle to Late Miocene) of the southern Taranaki Basin. Our seismic geomorphological analysis (including seismic facies, slicing and seismic attributes techniques) shows that the channels belong to two main groups including isolated and amalgamated stacks, which can further include high sinuosity-meandering, low sinuosity-meandering, and straight channels. In addition, gamma-ray logs indicated cylindrical, bell and serrated stacking pattern of sandstone within thick shale interval that indicated the presence of submarine channels in the study area. Furthermore, the complicated spatial interactions of the channels (including architectural variation) and their temporal evolution reflects the activities of diverse turbidity flow regimes and a balance between waxing and waning energy phases. Importantly, the evolution, architecture and scale of the channel was influenced by eustatic sea-level fall in the late Waiauan at ca. 13 Ma, dominantly increased in clastic sediment supply (climate), palaeomorphology, and regional far-field stresses related to rifting and contraction in the Middle Miocene.