An abrupt cooling event recorded around 73 kyr in western South Atlantic

This paper presents the record of sea surface temperature and planktonic foraminifera cold species for the last 130 kyr of a deep sea marine piston core (GL-854) from western South Atlantic. Our data shows a prominent and consistent feature around 73 kyr when an abrupt drop in sea surface temperature, both artificial neural network and oxygen isotope-based, was recorded. Additionally, our oxygen isotope curve presents a positive excursion and two cold-water planktonic foraminifera (Globoconella inflata and Neogloboquadrina incompta) remarkably increased their abundances. The benthic oxygen isotope record did not indicate any change while planktonic indicators were intensely disturbed. This cooling episode should be explained by a strong and abrupt mechanism able to promptly affect the surface ocean but not the deep ocean. It seems to be one of the coldest intervals during the last 130 kyr. Here, we discuss some hypothesis for this abrupt cooling recorded in the South Atlantic, including the speculative climatic impact of Toba super-eruption.