Quaternary sea-level changes and aeolianites in the Fernando de Noronha archipelago, northeastern Brazil

摘要

Finite and directional sea-level indicators were found in the Fernando de Noronha Archipelago, Brazil, showing that in the Mid- to Late Holocene the sea level was similar to present, and had been stable for at least the preceding 500 years. This sea-level behaviour is different from that observed in the nearest continental coast (of northeastern Brazil), suggesting a slight sinking of the archipelago relative to the mainland. The Caracas Formation that corresponds to the conspicuous aeolianites found on the archipelago was subdivided into two chronological units (Ⅰ and Ⅱ). Unit Ⅰ is Pleistocene, formed before 50,000 BP, and could correspond to an interglacial stage. Unit Ⅱ was formed during the Holocene, and was built up over the period from 10,700 to 5700 BP, meaning that the sand dunes were transgressive and formed during the postglacial sea-level rise prior to a Mid-Holocene maximum at 7000-5000 BP.