Estimating tectonic uplift of the Cape Fear Arch (south-eastern United States) using reconstructions of Holocene relative sea level

We use relative sea-level (RSL) reconstructions and a spatiotemporal statistical model to estimate the rate of uplift of the Cape Fear Arch, a Mesozoic structural high, during the last ~4000 years. We reconstructed RSL using 12 radiocarbon-dated samples of basal salt-marsh sediment preserved at Elizabeth Creek Marsh on the Cape Fear River. The new data show that RSL rose by ~3m during the past ~4.6 ka at an average rate of 0.67±0.12mm a^-1. RSL reconstructions from other sites in southern North Carolina (which have rates of 0.91±0.10 to 0.84±0.24mm a^-1) probably show (P>0.9) higher rates of regional RSL rise for the same period, while sites from northern South Carolina (which have rates of 0.72±0.17 to 0.80±0.21mm a^-1) probably (P>0.67) show the same. We attribute the differences between Elizabeth Creek Marsh and neighboring regions to uplift of the Cape Fear Arch, which we estimate to be 0.24±0.15mm a^-1. Uplift of the arch may be responsible for lower rates of 20^th century RSL rise recorded by the Wilmington tide gauge relative to rates measured elsewhere along the US mid-Atlantic coast.