Evidence for coral island formation during rising sea level in the central Pacific Ocean

• Published in: Geophysical research letters Vol. 41; no. 3; pp. 820 - 827
• Main Authors: Kench, Paul S., Owen, Susan D., Ford, Murray R.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 16-02-2014; John Wiley & Sons, Inc
• Subjects: Accumulation; Archipelagoes; atoll islands; Atolls; Buildings; Chronology; Coarsening; Corals; Deposition; Evolution; Geomorphology; Gravel; Holocene; Islands; Marshall Islands; Migration; Pacific Ocean; Platforms; Prehistoric era; Radiometric dating; reef island evolution; Reefs; Ridges; Sand; Sea level; sea level change; Sea level rise; Sediment; Sediments; Time measurement; Marshall Islands; Pacific Ocean
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2013GL059000

The timing and evolution of Jabat Island, Marshall Islands, was investigated using morphostratigraphic analysis and radiometric dating. Results show the first evidence of island building in the Pacific during latter stages of Holocene sea level rise. A three‐phase model of development of Jabat is presented. Initially, rapid accumulation of coarse sediments on Jabat occurred 4800–4000 years B.P. across a reef flat higher than present level, as sea level continued to rise. During the highstand, island margins and particularly the western margin accreted vertically to 2.5–3.0 m above contemporary ridge elevations. This accumulation phase was dominated by sand‐size sediments. Phase three involved deposition of gravel ridges on the northern reef, as sea level fell to present position. Jabat has remained geomorphically stable for the past 2000 years. Findings suggest reef platforms may accommodate the oldest reef islands in atoll systems, which may have profound implications for questions of prehistoric migration through Pacific archipelagos.
Key Points
Evidence of Pacific reef island formation in latter stages of sea level rise
Reef platforms accommodate the oldest coral reef islands in atoll archipelagos
Islands formed at higher sea level have been stable for the past 2000 years