Archaean microfossils lived in oceans at over 40°C

In an article recently published in the journal Geochemical Perspectives Letters, a team of French researchers addressed this question by analysing the oxygen isotopic composition of microfossils extracted from rocks aged between 600 million and over 3.4 billion years, enabling them to reconstruct the oxygen isotopic composition of the oceans over geological time. According to the authors, this new constraint, coupled with the record provided by cherts, sedimentary rocks precipitated in the oceans, suggests that temperatures at the Earth’s surface have fallen steadily by around 50-60°C over the last 3.5 billion years.

This work was carried out by a team of researchers from the Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC: CNRS / IRD / MNHN / Université Pierre et Marie Curie), the Institut de Physique du Globe de Paris (IPGP: CNRS / IPGP / Université Paris-Diderot / Université Sorbonne Paris Cité) and the Centre de Recherches Petrographiques et Géochimiques (CRPG: CNRS / Université de Lorraine).