Ecosystem changes after Early Cretaceous seawater intrusion into the proto-South Atlantic Ocean

Communications Earth & Environment, vol. 6

Abstract

The early evolution of the South Atlantic Ocean following the Cretaceous break-up of Gondwana is extensively recorded in rift basins along the conjugate margins of Africa and Brazil. For the Brazil side, divergent views of the source and pathway of the initial seawater incursion persist due to a paucity of recognized transitional sequences that document marine transgressive deposits over the continental interior. To address this, we conducted a high-resolution sedimentological and geochemical study through a core in the Campos Basin that encompasses the key lithologic switch from lacustrine carbonate to marine evaporite settings. Steroid lipid biomarkers, derived from pelagophyte marine algae, make a striking appearance in concert with a pronounced negative shift of 87Sr/86Sr ratios and coincident with the appearance of anhydrite. Importantly, the sulfur-sequestered biomarkers reveal a dynamic system where redox-stratified and anoxic conditions were amplified along with a deepening chemocline through the marine transition. During the break-up of Gondwana, a marine invasion from the proto-South Atlantic Ocean about 116 million years ago transformed the paleoecosystem of the Campos Basin, as revealed by the analysis of lipid biomarkers and carbonate isotopes from the east coast of Brazil

Authors 11

1. Jian Ma corresponding

   Massachusetts Institute of Technology · Shanghai Jiao Tong University

   Affiliation as printed

   Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

   School of Oceanography, Shanghai Jiao Tong University, Shanghai, China

2. Leonardo Fadel Cury

   Universidade Federal do Paraná

   Affiliation as printed

   Federal University of Paraná, LAMIR Institute, Curitiba, Paraná, Brazil

3. Anelize Manuela Bahniuk Rumbelsperger

   Universidade Federal do Paraná

   Affiliation as printed

   Federal University of Paraná, LAMIR Institute, Curitiba, Paraná, Brazil

4. Heidi L. Albrecht

   Shell (United States)

   Affiliation as printed

   Shell Exploration and Production Company, Houston, TX, USA

5. Erwin W. Adams

   Shell (Netherlands)

   Affiliation as printed

   Shell Global Solutions International BV, The Hague, The Netherlands

6. Joachim E. Amthor Aachen Division of Earth Sciences and Geography

   RWTH Aachen University

   Affiliation as printed

   Division of Earth Sciences and Geography, Rhine-Westphalia Technical University of Aachen, Aachen, Germany

7. Xingqian Cui

   Shanghai Jiao Tong University

   Affiliation as printed

   School of Oceanography, Shanghai Jiao Tong University, Shanghai, China

8. Antoine Crémière

   Centre National de la Recherche Scientifique · California Institute of Technology · Ifremer · Geo-Ocean

   Affiliation as printed

   Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA

   Geo-Ocean, Univ Brest, CNRS, Ifremer, UMR6538, F-29280, Plouzané, France

9. Kei Sato

   Universidade de São Paulo

   Affiliation as printed

   São Paulo University, São Paulo, São Paulo, Brazil

10. Kristin Bergmann

    Massachusetts Institute of Technology

    Affiliation as printed

    Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

11. Roger Everett Summons corresponding

    Massachusetts Institute of Technology

    Affiliation as printed

    Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA