Holocene sea level record of Tongatapu, Kingdom of Tonga, from pollen analysis of mangrove sediments

摘要: Many Holocene sea level studies are imprecise owing to use of fossil indicators that have a broad relationship with mean level, and lack quantitative determination this from the present day environment. This study assesses record available pollen analysis mangrove sediments, Tongatapu, Kingdom Tonga, in S.W. Pacific. Surface samples were taken across transect largest swamp, on fringes Fanga 'Uta Lagoon at Folaha, show assemblages representative species zonations occur different elevations. Eleven cores pulled transect, seven other areas Tongatapu stratigraphy related changes during Holocene. Pollen was carried out two peat units, using elevations modern analogue surface give high resolution reconstruction for these periods. Early rise is shown, calcitic mud terrestrial pedogenic origins being encroached by mangroves. lower shows large forest existed Folaha site broadly 7000 5500 radiocarbon years before (BP), rose period rate 12 crn1100 years. early has no known equivalent islands Pacific, attributable sheltered conditions Folaha. A mid-Holocene highstand shown presence lagoon sediments site, estimated between 4500 2500 BP, fell towards levels. more recent fall less than 50 cm allowed mangroves again occupy area. upper peats sudden shift indicates tectonic event, alien review charts identify an earthquake 1853 as cause.