Sea-Level Changes and δ18O Record for the Past 34,000 yr from Mayotte Reef, Indian Ocean

Abstract

New sea-level and δ¹⁸O curves for the past 34,000 yr, based on uranium–thorium chronology, are proposed for the southwestern part of the Indian Ocean. The archives include cores drilled from onshore coral reefs and submersed samples from foreslope corals of Mayotte in the Comoro Islands. The Mayotte sea-level curve shows a lowstand of 145 ± 5 m below the present level during the last glacial maximum dated at 18,400 yr. This lowstand is supported by the maximum¹⁸O enrichment in the coral colonies. The residual signal (Δδ¹⁸O), controlled by sea-surface temperature changes, indicates that surface waters 18,400 yr ago were approximately 5°C cooler than present. The deglacial sea-level rise is clearly recorded, with a mean rate of about 1.7 cm yr⁻¹between 18,400 and 10,000 yr ago. The deglaciation phase is characterized by a strong¹⁸O depletion marked by two pulses related to meltwater discharges into the North Atlantic Ocean but also characterized by responses specific to the tropical Indian Ocean.