Holocene Antarctic melting and lithospheric uplift history of the southern Okinawa trough inferred from mid- to late-Holocene sea level in Iriomote Island, Ryukyu, Japan

Relative sea level deduced from fossil oysters and mangroves are reported for Iriomote Island, Ryukyus, southwestern Japan. Radiocarbon-dated fossil oysters, as well as previously analyzed mangrove muds, are compared to geophysical and glacio-hydro-isostatic adjustment (GIA) models that describe Earth deformation due to changing surface loading. The Holocene-high-stand (HHS) inferred from oyster fossils (Saccostrea echinata and Saccostrea malaboensis) is 2.7 m at ca. 3500 years ago, after which sea level gradually fell to present level. The HHS magnitude attributed to GIA for the last ca. 4000 is between 1 and 1.5 m above present day sea level, and the residual indicates the long-term lithospheric uplift rate of the island. The timing of peak HHS also indicates that late Holocene melting mainly from Antarctica ceased by approximately 4000 years ago.