Uranium-series ages of Pleistocene marine deposits on the Islands of Curaçao and La Blanquilla, Caribbean Sea

Abstract

Sequences of 3, resp. 5 Pleistocene limestone terraces crop out on La Blanquilla and Curaçao. All represent Pleistocene reefs which have been uplifted. Diagenesis of the corals shows a sequence of increasing alteration with elevation (or age) of the terraces. Samples of corals in growth position were collected for dating of the Lower and Middle Terraces of Curaçao, and of the Limestone Terraces 1 and 2 of La Blanquilla. 230Th age determinations indicate that the Lower Terrace of Curaçao (10 m above sea level) and the Limestone Terrace 1 at La Blanquilla (7-10 m above sea level) formed contemporaneously at about 130,000 years ago, and are time-equivalent to Terrace III of Barbados and to the main limestone terrace of La Orchila island, all deposited during the last interglacial. No equivalents of Barbados I and II Terraces were found; they are probably below sea level, indicating that the Netherlands Leeward Islands and La Blanquilla were less uplifted than Barbados. The age of the higher terraces of Curaçao and La Blanquilla is uncertain because of diagenetic changes, but may be estimated as about 325,000 years for the Limestone Terrace 2 of La Blanquilla and about 570,000 years for the Middle Terrace of Curaçao.