Aptian-Albian paleoenvironmental geochemistry: Araripe Basin, Northeastern Brazil

Abstract

The geochemical record of the early Aptian and the transition to the Albian exposes the presence of Hg/TOC anomalies, revealing the interference of LIPs in paleoenvironmental changes in the Araripe basin. Redox-sensitive (VEF, FeEF, CrEF, MnEF, PbEF, V/Cr, V/V + Ni and V/Ni) and paleoproductivity (CuEF, ZnEF, NiEF and BaEF) proxies in the Santana Group (Barbalha, Crato and Romualdo formations) indicate conditions ranging from oxic to anoxic, and increased paleoproductivity and of trace elements concentrations during LIPs activation. Statistical analyses demonstrated that volcanism was associated with oscillations in paleosalinity (Sr/Ba) and detrital supply (Al). LIPs activity was responsible for the emission of CO2 into the atmosphere, generating paleoclimatic changes in temperature (δ18O), a crisis in the productivity of calcifying organisms (δ13Ccarbonate), and an increase in the load of organic matter (TOC). We suggest that trace elements anomalies found in the early Aptian (Barbalha Formation) are associated with Ontong Java Plateua (OJP), responsible for OAE 1a, while the volcanism's proxies found in the Romualdo Formation occurred due to the Kerguelen South Plateau (SKP) volcanism, triggering the OAE 1 b.