Geochemical and sedimentary features of the unusual association between hybrid carbonates and beachrocks in the Southeastern Brazilian Coast

Abstract

Rocks formed in beach environments during the Holocene constitute strong evidences of relative sea level variations (RSL) and supply important data for paleoenvironmental reconstruction. At the southeastern Brazilian coast, an unusual association of lithofacies composed of hybrid carbonates and beachrocks was identified on the Parati beach in the Espírito Santo state. In this study, radiocarbon dating and sedimentary and geochemical characterization of five lithofacies were conducted, with the aim of reconstructing the paleoenvironmental conditions of deposition and cementation of this facies association. The lithofacies were classified as quartzarenites, bioclastic quartzarenites, hybrid carbonate and hybrid boundstones, with ages ranging from 2600 to 700 cal yr BP. Sedimentary and geochemical changes observed in these five lithofacies of the shallow shelf off southeastern Brazil reinforce evidence relative sea level variations during the Holocene.