Kench, Paul, Owen, Susan, Beetham, Edward, Mann, Thomas, McLean, Roger and Ashton, Andrew (2020) Holocene sea level dynamics drives formation of a large atoll island in the central Indian Ocean. Global and Planetary Change, 195 . p. 103354. DOI

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The impact of global environmental change on coral reef islands is uncertain with few
studies having resolved the critical controls on island formation and change. Based on
detailed, topographic surveys, sediment analysis and radiometric dating, we present a
multi-phase model of the formation of a large inhabited reef island in the central Indian
Ocean in response to Holocene sea level dynamics and transformations in reef
development and reef ecology. The initial phase of island building occurred later than
elsewhere reported in the Maldives, 2,500-2,100 years ago during the mid-Holocene
sea level highstand. The island was able to support habitation shortly thereafter.
Subsequent island expansion occurred as a consequence of relative sea-level fall and
emergence of the reef platform that forced a transition in reef flat ecology and dominant
sediment producers that contributed to island accumulation to the southwest. Smallscale
sea level oscillations (± 0.8 m) over the past two millennia has driven periods of
island accumulation, that intermittently reactivate geomorphic processes around the
island shoreline. Significantly, the multiple phases of island development have
occurred while the island has been continuously inhabited, demonstrating the adaptive
capacity of the island community to multiple phases of change. Results highlight the
complexity of reef island development and indicate that future physical trajectories will
vary depending on not only relative sea level change, but how such changes modify
water depth and wave regimes across reef surfaces, and changes in dominant
sediment producers able to contribute island building. This interrelationship differs
between sites within and between reef regions and may account for currently
expanding islands on reef surfaces.

Document Type: Article
Programme Area: PA2
Research affiliation: Biogeochemistry and Geology > Geoecology & Carbonate Sedimentology
Affiliations > Not ZMT
Refereed: Yes
Open Access Journal?: No
DOI etc.:
ISSN: 09218181
Date Deposited: 12 Sep 2020 11:17
Last Modified: 24 Nov 2021 12:51

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