Testing the potential of Serpulidae tubes as an indicator of past relative sea-level collected from shored wave dissipating blocks along the Pacific and Japan sea coast of northeastern Japan

Abstract

Relative sea-levels (RSL) in the past can be used to understand crustal movements, as paleo-shoreline elevations can be modified by seismic activities [1]. To assess short-term crustal movements, reliable RSL proxies are key in age determination to derive precise tectonic activities. The Tohoku region in northern Japan has complex oceanographic setting since two currents, cold Oyashio and warm Kuroshio being merged in the region. Here, we assessed the potential of Hydroides ezoensis (HE), as a new proxy of RSL. The 14C concentrations of HE collected in the Tohoku region were measured and compared with previous studies that reported radiocarbon values of the surface ocean. Results showed HE possesses summer surface 14C. This suggests that HE is suitable to be used as a reliable RSL proxy that can reliably provide age information without having influences from radiocarbon depleted Oyashio. Thus, HE could be used as a reliable proxy to understand paleo-RSL.