Geomorphologic control on the evolution of Middle-Late Miocene submarine channels in the Southern Taranaki Basin, New Zealand

Abstract

The Clifdenian-Tongaporutuan interval in the Southern Taranaki Basin experienced significant activity by turbidity flows during the Middle to Late Miocene, resulting in the formation and burial of several submarine channels. The chronological evolution of these channels is difficult to prove due to their architectures, repeated cut-and-fill, stacking patterns, erosive and erosional natures, and spatial-temporal interactions. In this study, high-quality 3D seismic reflection data from three industrial seismic reflection surveys, combined 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, which included seismic facies, slicing, and seismic attribute techniques, revealed that the channels can be classified into two main groups: isolated and amalgamated stacks. These groups may further include high sinuosity-meandering, low sinuosity-meandering, and straight channels. Additionally, gamma-ray logs indicated cylindrical, bell, and serrated trends of sandstone within a thick shale interval, indicating the presence of submarine channels in the study area. Furthermore, the complex spatial interactions of the channels, including architectural variation, and their temporal evolution reflect the activities of different turbidity flow regimes and the interaction with seafloor topography. These interactions, along with a balance between waxing and waning energy phases, influenced the evolution, architecture, and scale of the channels. Importantly, the eustatic sea-level fall in the late Waiauan at approximately 13 Ma, increased clastic sediment supply (climate) and tectonic activities related to rifting and contraction in the Middle Miocene played a significant role in shaping the channels. The workflow, integrated analysis, findings, and the unique case study area presented in this study contribute to research on submarine channels and provide insights into seismic geomorphology, seismic attributes, paleoenvironment reconstruction, the Taranaki Basin, climate, sea-level, and tectonics.