The Brazilian sea-level curves: a critical review with emphasis on the curves from the Paranaguá and Cananéia regions

Abstract

Relative sea-level curves for the mid- to late-Holocene have been proposed for eight different sectors along the Brazilian coast. This paper aims to review the data used to construct the curves proposed for two sectors, the Paranaguá and Cananéia regions in southeast Brazil. More specifically, we analyze the palaeo-sea-level indicators (vermetid tubes, shells, wood fragments and shell-midden deposits) related to (1) the sea-level maximum of the mid-Holocene and (2) the two secondary oscillations that would have occurred between 4100-3800 years B.P. and 3000-2700 years B.P. The sedimentary deposits of the coastal plain as well as vermetid datings suggest a mid-Holocene sea-level maximum between + 3.5 and +4 m. The great majority of the indicators used to infer the secondary oscillations in previous studies were derived from shell middens. Besides being unreliable palaeo-sea-level indicators. these data also showed inconsistencies that undermine the existence of such oscillations. The plot of all the data derived from vermetid samples found along the Brazilian coast also indicate a rather smoother sea-level fall in the last 5100 years.