Detailed 3-D Models of New Zealand Barrier Stratigraphy Provide Insight into Coastal Evolution in Various Spatial and Temporal Settings

The application of ground-penetrating radar (GPR) to five prograding barriers around northern New Zealand has produced detailed three-dimensional morphostratigraphic models. These barriers exist within a variety of geologic settings ranging from the high-energy, sediment rich west coast to the lower-energy, sediment starved east coast. Additionally, a composite Pleistocene-Holocene barrier exists along the east coast providing the unique opportunity to study barrier evolution not only through space but time. Nearshore, beach and dune facies delineated within each barrier lithosome form regressive facies successions with differences in shoreface geometry between sites. These differences detected within the stratigraphy are reflected in the contrasting depositional settings of the west coast dissipative morphodynamic state versus the east coast intermediate morphodynamic state. The replication of this stratigraphic form along shore and over successive sea-level stands indicates that the present day barrier evolution and depositional setting is similar over various spatial and temporal settings.