Preservation factors during Cretaceous Oceanic Anoxic Events in the Espírito Santo Basin

Published: 25 August 2022| Version 2 | DOI: 10.17632/59xwm446hf.2
Igor Venancio, Thiago Santos, Fellippe Bione, Andre L. Belem, Marcelo Bernardes, Rut Díaz, Manuel Moreira Ramírez, Victor Carreira, Andre Spigolon, Igor Souza


The Oceanic Anoxic Events (OAEs) are characterized by enhanced accumulation of organic matter in marine sediments. However, there is still an ongoing debate regarding the interplay between production and preservation during these events. Moreover, few studies provide quantitative es-timations of primary productivity and/or the amount of carbon preserved during the OAEs. Here, we use geochemical data from multiple wells located at the Espírito Santo Basin that cover the in-tervals of events OAE1d and OAE2 to provide quantitative estimates of preservation factors. Our results show enhanced preservation during OAEs compared to modern conditions, and a stronger preservation during OAE1d compared to OAE2 in the Espírito Santo Basin. The amount of pre-served carbon could reach up to 8.6 % during OAE1d, depending on productivity of the system. In addition, we show that such improvement in preservation is linked to the bottom-water with low-O2 concentrations, and not due to fast burial caused by high sedimentation rates. Our findings are extremally relevant for organic carbon and source rock modelling studies, since model simula-tions need quantitative estimations



Cretaceous Period, Carbon, Environmental Anoxia, Petroleum