Late Cretaceous astrochronology, organic carbon evolution, and paleoclimate inferences for the subtropical western South Atlantic, Espírito Santo Basin

Published: 10 January 2022| Version 1 | DOI: 10.17632/v77m5yz3tm.1
Thiago Santos


Cyclostratigraphy has revealed the quasi-periodic nature that globally distributed sedimentary succes- sions present through the Phanerozoic. This is mainly the case of the strong eccentricity-related greenhouse climate of the Cretaceous period, a time interval in which the long-eccentricity 405-kyr cycle has been routinely used to constrain high-resolution astronomical time scales. Despite the importance of the South Atlantic opening to the evolution of the Cretaceous climate and carbon cycle, few investigations have applied the modern cyclostratigraphic analysis to explore the eventual orbital pacing of the Cretaceous South Atlantic successions. We use geophysical and geochemical data analysis from the Petrobras well ES-1 (offshore Espírito Santo Basin to develop a floating and anchored astro- nomical time scale (ATS) and infer the relation between sedimentation rate and TOC accumulation. Additionally, we estimate the net primary productivity (NPP) during intervals of high TOC accumulation. Our results show a pervasive orbitally-driven forcing imprint according to the Milankovitch spectral peak ratio as predicted to Cretaceous times, with a prominent occurrence of a 405-kyr long-eccentricity cycle, being used to constrain the elapsed time. An abrupt shift in the GR data likely associated with the Cretaceous e Paleogene boundary was used to anchor our floating ATS. The evolutionary Average Spectral Misfit (eASM) and Correlation Coefficient (COCO/eCOCO) tests demonstrate that the sedimen- tation rate can have contrasting effects over the organic matter burial, which is likely related to the large- scale paleogeographic configuration. Our study exemplifies that orbitally-driven sedimentation can be used to build high-resolution chronology for Brazilian marginal basins



Natural Sciences, South Atlantic, Paleoclimatology, Late Cretaceous, Cyclostratigraphy