PRELIMINARY RESEARCH PLAN FOR INTEGRATING RELATIONSHIPS OF COASTAL FEATURES, KAURI TREES, AND CLIMATE VARIATION

Coastal features on the coast of New Zealand preserve records of climate variation as the sea level has varied over time. Long-lived and well preserved kauri trees (Agathis australis) from the North Island of New Zealand possess a potential to preserve high-resolution temporal responses to climate variation including El Niño-Southern Oscillation and provides an ideal location to study variations to the coastal and wetland system driven by climate change and anthropogenic impacts. Together, the wetlands, beaches and kauri trees form a unique dataset that presents a suite of climate proxies. Previous studies have used kauri trees to reconstruct ENSO conditions over > 4,000-year period. A detailed chronology of kauri trees and climate conditions could provide an understanding of the development of the coastal system over decadal to millennial to ice age scales to determine a longer impact on the dynamics of beach systems. The objectives of this study are: 1) to determine and understand how past variation in climate have impacted the beach and wetland systems, 2) to develop a method to extract the archived former beach deposits, and 3) to correlate local beach and wetland climate proxies with known regional and global records. The team will employ a MALA Geosciences GTX HDR ground penetrating radar system with 160, 480 MHz antenna arrays to survey beach and wetland systems that range in age from modern to MIS 7. The GPR data will be correlated spatially to known excavations and boreholes. Newly acquired hand- and vibration-driven sediment cores will augment the ground truthing and provide samples to correlate GPR horizons and develop chronological control using 14C or OSL on key horizons. Initial locations for study may include east-facing beaches and associated wetlands of the far northern area of Doubtless and Rangauna bays and the more centrally located Marsden Point and Ruakaka. Locations will be refined during a January 2015 reconnaissance survey. The results will provide insight into how sea level preserves palaeo-climate information and correlation with local and global records will elucidate the sensitivity of coastal systems to climate-based alterations in processes. This research will help decipher natural and anthropogenic coastal changes and impacts to New Zealand, pre and post colonization.