Preliminary results on holocene sea-level changes on Ceará Coast / Brazil

Abstract

The Mid-Holocene sea-level in the East and South Brazilian coast has shown a significant rising in comparison to the current mean sea level. In Ceará State Coast, Northeastern Brazil, however, there is a lack of studies investigating sea level variation. In order to obtain information on Holocene sea-level changes, an intense survey on specific sites throughout the 573 km coast of Ceará was done and recovered more than 30 cores sampling up to 26 m of sediment profiles from the estuaries of Jaguaribe and Coreaú Rivers located in the South-east and North-west of Ceará coast, respectively. Main attention was given to the large sections well developed beach rocks. These rocks were not found in positions higher than the current high-water line. Mangrove sediments occur in both investigated estuaries are also concentrated in places such as in Itarema. 14C analysis of mangrove sediments are in progress and sea-level curves are being worked out by dating derived from mangrove horizons of different depths. Lakes have been formed during sea-level rise due to low sedimentation rates in the investigated area. This led to find the extent of the Holocene sea-level variation. This work also includes sedimentary, geochemical and mineralogical analysis as a tool to describe the Holocene history of these estuaries and to contribute to the climate history of Ceará State.