Holocene sea level changes and reef development in the southwestern Indian Ocean

Abstract

The sedimentological and chronological study of Holocene reef sequences recovered in drill cores through modern reefs of Mauritius, Re´union Island and Mayotte allows the reconstruction of sea level changes and reef growth patterns during the Holocene. The branching-coral facies systematically predominates over coral head facies throughout the Holocene reef sequences, and Acropora is the main frame builder among the branching forms. The reconstructed sea level curves, based both on identification of coral assemblages and on radiometric U/Th ages, are characterized by a rapid rise between 10 and 7.5 ky BP, followed by a clear inflection between 7.5 and 7 ky BP. The stabilization of sea level at its present level occurred between 2000 and 3000 years ago, probably without a higher sea level stand. Rates of vertical reef accretion range between 0.9 and 7 mm. y\.

Successive phases of Holocene reef flat development: Evidence from the mid- to outer Great Barrier Reef

“…These results are broadly consistent with both wider Indo-Pacific (Cabioch et al, 1995, Camoin et al, 1997, Montaggioni, 2005 and Caribbean reefs (Neumann and Macintyre, 1985, A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT Hudson, 1998, Gischler andHudson, 2004), showing both initial vertical accretion and then lateral progradation of the reef flat in response to sea-level stabilisation and reduced accommodation. Differences in the precise timing of when these reefs first approached sea level and the transition to progradational growth at these locations (ranging from 6 ka to 2 ka) are related, in part, to differences in the timing of relative sea-level changes that result from glacial isostatic adjustment or tectonic movement (Lambeck et al, 2010).…”

Holocene Relative Sea-Level Changes from Near-, Intermediate-, and Far-Field Locations

“…At sites on the mainland of southeast Africa, RSL reached~2.5 to 3.5 m above present by 6 ka [144]. Stable islands off the coast of southern Africa (Mauritius, Reunion and Mayotte) record no highstand (with RSL stabilizing at present level by 3 ka) because these small atoll islands subside with the ocean floor from hydro-isostatic loading [44,146,147]. A recent study of late Holocene RSL in the Seychelles [148], a location demonstrated to closely measure eustatic sea level [39], showed RSL rising <2 m in the last 2 ka.…”

An Updated Account of the Vascular Flora of the Iles Eparses (Southwest Indian Ocean)

“…The islands probably peaked at a height of 120-140 m above sea level at the Last Glacial Maximum (LGM, 25,000 years ago). Deglacial sea levels rose irregularly in stages to present, with a maximum oscillation at about 7000-6000 years BP, to about 1-3 m higher than present sea level (Camoin et al, 1984;Camoin et al, 1997). At that time Europa, Juan de Nova and Grande Glorieuse were not entirely submerged, but Tromelin undoubtedly and the Ile du Lys probably were.…”

“…This result is explained by the fact that they are young oceanic islands, geographically close to huge biodiversity reservoirs with comparable physical and abiotical conditions. Moreover, according to the available data (Camoin et al, 1984;Camoin et al, 1997;Virah-Sawmy et al, 2009;Woodroffe and Horton, 2005) the sea level has changed considerably since the likely formation of the Iles Eparses during the peak of the last interglacial, Marine Isotope Stage 5 (MIS5, 120,000 years ago). The islands probably peaked at a height of 120-140 m above sea level at the Last Glacial Maximum (LGM, 25,000 years ago).…”