Far-Field Test of the ICE-4G Model of Global Isostatic Response to Deglaciation Using Empirical and Theoretical Holocene Sea-Level Reconstructions for the Fiji Islands, Southwestern Pacific

Abstract

Holocene paleosea-level data for Fiji, represented by 77 dates and emergence magnitudes, are presented, screened, and adjusted. Most data are from coral microatolls, potentially the most precise paleosea-level indicators in this region. Holocene sea-level changes are reconstructed for five areas within Fiji known to have had different late Quaternary tectonic histories. Resulting analysis suggests that postglacial sea level in Fiji reached its present level more than 6900 14C yr B.P. It also suggests either that a single maximum 5650–3200 14C yr B.P. (perhaps +2.19 m but more likely +1.35–1.50 m) occurred or that two maxima occurred 6100–4550 14C yr B.P. (+0.75–1.85 m) and 3590–2800 14C yr B.P. (+0.90–2.46 m). Broad agreement exists between these empirical sea-level reconstructions and those derived theoretically using the ICE-4G model (predicted maximum ∼4000 14C yr B.P.; ∼+2.1 m). This suggests that both methods of reconstructing Holocene sea-level changes are valid, as are the assumptions underpinning the ICE-4G model. The most important of these, that eustatic sea level had effectively stopped rising by late middle-Holocene time (5000–4000 yr B.P.), is confirmed by observations from Fiji.