Holocene relative sea-level change of Fujian coast, southeastern China: Geological records and comparison with glacio-hydro isostatic adjustment modelling

Reconstruction of high-quality Holocene relative sea levels (RSL) based on geological records can provide important past analogue and long-term reference for coastal societies to make better prediction and preparation for future sea-level rise. In the last decades, several Holocene RSL curves have already been published from Fujian coast, southeastern China. However, obvious differences and even contradictory results existed in these early-stage researches. At the same time, the mechanism and factors which control the long-term RSL change in this area are also unclear. In this study, new and published RSL data have been compiled from Fujian coast. Attrib-ute information including location, age, elevation and indicative meaning of each data point has been re-examined and corrected. After that, a standardized Holocene relative sea level database which includes a total number of 183 data were established. On this basis, a new regional Holocene RSL curve was proposed by using the errors in vari-able-integrated gaussian process (EIV-IGP) statistical model. Finally, theoretical RSL change was predicted through solving the sea level equation (SLE). Combining the RSL geological records and GIA simulation results, conclusions are drawn as follow: (1) New Holocene RSL history of Fujian coast was reconstructed. 11.28–7.08 cal ka before present, RSL rose from (–23.55±6.94) m to (–1.51±1.80) m continuously; 7.08–4.08 cal ka before present, RSL rose slowly from (–1.51±1.80) m to (1.09 ±1.38) m; around 3.48 cal ka before present, RSL was about (1.35±1.23) m higher than modern sea level. Since then, the RSL has declined close to the modern position gradu-ally. (2) In the Early Holocene (11.28–7.00 cal ka before present), the RSL change was mainly controlled by the meltwater from continental ice-sheet; and since 7.00 cal ka before present, hydro-isostatic process dominated the regional RSL change. (3) Holocene sea level highstand existed during 6.75 –0.16 cal ka before present on Fujian coast. The highstand of sea level could be attributed to continental levering and ocean syphoning processes caused by GIA rather than tectonic movement. (4) Holocene RSL change showed spatial variability on the Fujian coast. Non-GIA factors including the compaction of unconsolidated strata, differential tectonic movements and tidal range changes, supposed to be related to this phenomenon.