Continuous record of reef growth over the past 14 k.y. on the mid-Pacific island of Tahiti

Abstract

Two boreholes were drilled through coralgal sequences in the barrier-reef edge of the mid-Pacific island of Tahiti, and their bases were radiometrically dated at 10.23 (±0.05) and 13.77 (±0.05) ka (thousand calendar years). The sequences are composed mainly of the reef-edge Acropora gr. danai-robusta and Hydrolithon onkodes assemblage, occasionally replaced by reef-slope tabular Acropora-Neogoniolithon or domal Porites-Lithophyllum assemblages. The response of reef growth to sea-level rise has varied according to the framework type, and vertical accretion rates have ranged from 9.3 to 20.6 mm ṁ yr −1 . From a general trend of long-term, continuous, sea-level rise tracked by growth, the reef-edge coralgal assemblages have experienced two distinct changes controlled by the antecedent paleotopography and internal reef processes. During the past 13.8 k.y. at Tahiti, there is no evidence of any reef-drowning event primarily caused by global glacio-eustatic perturbations as has been recorded in the Caribbean.