Ancient ocean oxygenation timeline is revealed by HU
The oxygenation of the Earth’s atmosphere and oceans and the emergence and evolution of life are pivotal episodes in the planet’s history. Now, a pioneering application of dolomite uranium–lead dating (U–Pb dating) – one of the oldest and most sophisticated radiometric techniques for determining the age of rocks and other objects – has been developed by scientists at the Hebrew University of Jerusalem (HU).
It can be used to date rocks that formed and crystallized from about a million years to over 4.5 billion years ago with routine precisions in the 0.1–1 percent range – shedding new light on the evolution of ancient marine environments.
By uncovering discrepancies in dolomite samples’ U-Pb ratios, the team developed a reliable proxy for reconstructing the levels of oxygen within ancient marine habitats in which the first animals emerged and evolved.
Dr. Uri Ryb and Dr. Michal Ben-Israel from HU’s Institute of Earth Sciences, along with their collaborators, revealed a significant rise in marine oxygenation during the Late Paleozoic era (400 million years ago), hundreds of millions of years after the emergence
of animal life.
These findings suggest that early animals evolved in oceans that were mostly oxygen-poor and deepened our grasp of interactions among ecosystems and the evolution of complex life forms.
Comprehending these relationships provides critical context for future observations of exoplanet’s atmospheres using the new generation of space telescopes in search of extraterrestrial life.
This important discovery in the field of earth sciences has just been published in the prestigious journal Nature Communications under the title “Late Paleozoic oxygenation of marine environments supported by dolomite U-Pb dating.”
The new approach reconstructs the rise of oxygen in ancient marine environments using such measurements in dolomite rocks spanning the last 1.2 billion years.
Most earth scientists have estimated the oxygen levels in ancient oceans from the composition of “redox-sensitive” elements preserved in ancient sedimentary rocks – but these compositions can be easily changed in the course of geological history. The team overcame this challenge by developing a new approach that uses dolomite U-Pb dating to detect signals of oxygenation that are resistant to such alteration, giving us an unbiased perspective on marine oxygenation dynamics.