DMCA
Middle to late Holocene coastal evolution along the south coast of Upolu Island, Samoa
BibTeX
@MISC{A_middleto,
author = {Ian D. Goodwin A and Eric E. Grossman B},
title = {Middle to late Holocene coastal evolution along the south coast of Upolu Island, Samoa},
year = {}
}
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Abstract
Stratigraphic surveys and sedimentological analyses of coastal sediments and reef cores along the south coast of Upolu Island, Samoa, reveal that during the middle Holocene this coast was characterised by barrier spits, open lagoons, and estuaries. These estuarine systems matured during the late Holocene, with progressive sedimentation and inlet closure, leading to the dominance of mangrove swamps in the past 1000 years. Contemporaneous with the transition of open estuaries to mangrove swamps was the aggradation and progradation of coastal plains. The coastal progradation since 700^1000 years BP is best explained by increased sediment availability and reduced incident wave energy at the shore resulting from the shallowing and subsequent cessation of reef crest accretion following the mid-Holocene sea-level highstand ca. V4500 yr BP. A small relative sea-level (RSL) lowering since 700^1000 years may have contributed to the positive sediment budget. This study highlights the need for island-wide coastal surveys to assess the relative roles of RSL, sediment budgets, and hydrodynamics on coastal evolution and stability. Differences in coastal evolution around Upolu Island may also be influenced by differential tectonic movements associated with late Holocene volcanism, coseismicity, and/or submarine landslides.
Keyphrases
upolu island south coast holocene coastal evolution coastal evolution progressive sedimentation reduced incident wave energy island-wide coastal survey middle holocene open lagoon subsequent cessation mangrove swamp small relative sea-level open estuary positive sediment budget reef core coastal plain increased sediment availability barrier spit estuarine system late holocene sediment budget mid-holocene sea-level highstand relative role sedimentological analysis coastal progradation coastal sediment yr bp inlet closure differential tectonic movement stratigraphic survey late holocene volcanism year bp
