Sequence stratigraphy and sedimentary evolution from Late Cretaceous to Quaternary in the Romney 3D seismic area, deep-water Taranaki Basin (New Zealand)

The study of sequence stratigraphy often focuses on shallow marine and shelf-edge regions, while research on deep-sea stratigraphic sequences remains relatively weak. This study, based on high-resolution 3D seismic data and drilling information, utilized sequence stratigraphy and seismic sedimentology as guidelines, and employed seismic interpretation methods to performed a division of deep-sea stratigraphic sequences within the Romney 3D seismic survey area in the deep-water Taranaki Basin, New Zealand. Furthermore, it analyzed the characteristics of typical depositional systems and their associated controlling factors. The findings are as follows: (1) Based on seismic reflection termination relationships and seismic facies characteristics, four second-order sequence boundaries and nine third-order sequence boundaries were identified, resulting in the delineation of three second-order sequences and twelve third-order sequences in the basin. (2) Five seismic facies were recognized, corresponding to five typical sedimentary bodies: mass transport deposits (MTDs), deep-water channel, levee deposits, deltaic deposits, and pelagic deposits. However, due to the relatively thin sedimentary thickness of carbonate sediments, the seismic facies characteristics of carbonate sediments cannot be discerned in seismic data, but can be identified based on well data. Deltaic sediments mainly developed during the rift stage of the basin, while carbonate sediments formed during the transition from a passive to an active margin. Deep-water channel and levee deposits and MTDs emerged during the active margin stage, while pelagic deposits are ubiquitous in marine environments. (3) The uplift of New Zealand's interior and climate-driven erosion caused the resurgence of clastic sediments, which began to be transported to the deep sea, the seafloor topography would directly affect the movement path of sediment gravity flow, and sediment supply can affect the development and evolution of sedimentary systems. (4) Event deposits boundaries, such as erosional scour surfaces formed by channels and unconformities created by MTDs, can serve as boundaries for the division of deep-water stratigraphic sequences. This study proposes a method for delineating deep-water stratigraphic sequences using event deposits, particularly suitable under conditions where the influence of relative sea-level changes on deep-water deposits is relatively weak. This research not only enhances the understanding of deep-water depositional sequences but also provides a reference for studies on the evolution of deep-water deposition and its controlling factors in research areas with similar geological backgrounds worldwide.