Holocene development of the Belize Barrier Reef

Previously, knowledge of the Holocene development of the Belize Barrier Reef (BBR)-the largest reef system in the Atlantic Ocean-was limited to one location (Carrie Bow Cay). We present new data from 11 rotary drill cores taken at 9 locations and 36 radiometric ages that indicate that the BBR was established from >8.26 to 6.68 ky BP on Pleistocene reef limestones, presumably deposited during oxygen isotope stage 5. The nonsynchronous start of Holocene reef growth was a consequence of variation in elevation of antecedent topography, largely controlled by underlying NNE-trending structures. From north to south, Pleistocene elevation decreases along these structural trends, probably reflecting differential subsidence and variations in karst topography. Reef anatomy is characterized by three facies. In order of decreasing abundance, these facies are represented by corals (mainly Acropora palmata and members of the Montastraea annularis group), by unconsolidated sand and rubble, and by well-cemented coral grainstones-rudstones. Holocene reef accumulation rates average 3.25 m/ky. The degree of reef consolidation is negatively correlated with Holocene thicknesses, indicating that slowly growing reefs are better cemented than fast growing ones. We present a Holocene sea-level curve for Belize based on 36 dates from this study and 33 dates from our previous studies in the area. (C) 2003 Elsevier B.V. All rights reserved.