C05_P04

Comprehensive update of marine reservoir values for New Zealand coastal waters to inform coastal hazard research

Turnbull J^1,2, Clark K¹, Ferrick T¹, Marshall B³, Howarth J⁴

¹GNS Science, Lower Hut, New Zealand, ²CIRES, University of Colorado, Boulder, USA, ³Te Papa Tongarewa Museum of New Zealand, Wellington, New Zealand, ⁴Victoria University of Wellington, Wellington, New Zealand

Accurate dating of coastal hazard events such as earthquakes and tsunamis typically hinges upon marine radiocarbon ages, and a well-constrained marine reservoir correction is vital to evaluating the size and frequency of large to great subduction earthquakes and tsunamis.     Yet in New Zealand, we have relied on only 31 ∆R values from four locations to estimate ∆R for the entire coastline.  Here we add 170 new measurements to the marine reservoir correction dataset for the mainland New Zealand and evaluated the influence of location, feeding method, living depth, environmental preference and species on the variance in ΔR values. We find there are no significant differences between ΔR values from suspension-feeding organisms compared to browsing/scavenger/carnivore-feeding organisms, and we find little variability between species that prefer estuarine environments to open coastal environments. This means that when dating shells from geological records, we do not need to take particular care to avoid certain species that may have anomalies of carbon precipitation in their shells.  Importantly, location is the dominant control on ∆R variability and we recommend the subdivision of New Zealand into five large regions, each with a different ΔR value.