In publica commoda

Press release: Sedimentary rocks reveal ocean floor cooling

No. 153 - 15.10.2025

Research team identifies oxygen isotopes in “cherts” as indicator of heat flow on early Earth

 

Rocks store information from long ago. For instance, their composition can reveal the environmental conditions during their formation. This makes them extremely important in climate research. This led a research team at the University of Göttingen and the GFZ Helmholtz Centre for Geosciences to investigate the following: do “cherts” – sedimentary rocks that form when silica-rich sediment mud is buried hundreds of meters deep – reveal anything about the climate of the past? The study found that oxygen isotopes in cherts do not show clear indicators about the early climate. However, they do record how much heat was released from the hot interior of the Earth to their location on the seafloor. This is crucial for understanding the early Earth: the findings allow researchers to understand the conditions on the Earth's surface up to 3.5 billion years ago. The research was published in the journal Geology.

 

Cherts from the Shatsky Rise oceanic plateau in the western Pacific east of Japan, together with data from international drilling projects, show that the composition of the three oxygen isotopes – known as 16O, 17O and 18O – in rocks changes with the heat flow, which varies in intensity depending on their location on the seafloor. In places where the Earth's oceanic crust has only recently formed from rising magma more heat flows to the Earth's surface. Older oceanic crust, on the other hand, has a low heat flow because the crust has had time to cool down. This is the first time that researchers have managed to measure the amount of energy flowing through the Earth's crust using oxygen isotopes in cherts. They used their own calculation model and verified their results with independent measurements in the world's oceans.

 

“Our method enabled us to measure – for the first time – how much heat flowed through the Earth's crust in the past and thus interpret and understand a piece of Earth's history,” explains lead author Oskar Schramm, who carried out the research at Göttingen University’s Geosciences Centre and is now pursuing research at Ruhr University Bochum. Professor Michael Tatzel, who supervised the research, adds: “Next, we want to clarify why some cherts show unusual oxygen isotope patterns that were not in equilibrium with the seawater at the time they formed. Initial findings from our recent findings suggest that volcanic ash may play a crucial role.”

 

Original publication: Schramm, O., et al. “Oxygen isotopes in cherts record paleo-heat flow on Shatsky Rise (Western Pacific Ocean)”. Geology (2025). DOI: 10.1130/G53296.1

 

Contact:

Professor Michael Tatzel

University of Göttingen

Geosciences Centre
Department of Sedimentology and Environmental Geology

37077 Göttingen, Germany

Tel: +49 (0)551 39-21791

Email: michael.tatzel@uni-goettingen.de

www.uni-goettingen.de/en/633807.html