Indicators of Holocene sea level changes along the coast of the states of Pernambuco and Paraíba, Brazil

Abstract

This study deals with the Holocene relative sea level (RSL) changes along the Brazilian northeastern coast, in particular along the states of Pernambuco and Paraíba. It presents 25 sea level superficial indicators, dominantly of a biological nature (i.e., vermetid gastropod tubes encrusted on rocky surfaces, as well as mollusk shells in live positions contained within beachrocks and paleomangrove deposits). Moreover, diatomological and palynological analyses have been carried out on a drilling core obtained from the Olhos d'Água lagoon (Southeastern Recife, Pernambuco state) with a length of about 2.7 m and age of about 8,300 cal yr BP at the base. The envelope RSL change curve obtained through the interpretation of the data indicates that, after reaching the current level ~ 7,400 cal yr BP, a sea level culmination of ~ 3 m above sea level was attained between 4,000 - 5,000 cal yr BP, and a general trend of sea level drop occurred until the present, with possible phases of slight oscillations. This is consistent with the oscillation frequency of microscopic marine and freshwater organisms in the sediment core.