Curtin University: lead isotopes show ancient crustal sources vanished 2.75–2.63 billion years ago
Lead isotope data from rocks of several cratons point to a shift in how Earth's crust formed in the Neoarchaean. The authors link it to more efficient crustal recycling.
Researchers at Curtin University, led by Janne Liebmann, used lead isotope data from rocks of multiple cratons to locate a turning point in how Earth's crust formed. The study was published on 10 November 2026 in Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences. According to the authors, a distinctive lead isotopic signature of ancient crust largely disappears from the accessible global rock record after 2.75–2.63 billion years ago (Ga) doi.org
Proceedings of the Royal Society A Mathematical Physical and Engineering Sciencesdoi.orgOpen source ↗.
Lead isotopes as a record of early crust
Lead isotopes give a time-resolved record of planetary differentiation. Unlike commonly used systems such as Lu–Hf, they are particularly sensitive to fractionation within the crust. Plate tectonics is hard to date because the process destroys much of its own evidence by recycling crust deep inside the planet.
The team searched for the fingerprint in thousands of rocks spanning almost four billion years of Earth's history, Liebmann said. New crust often forms by melting older rock, which leaves a characteristic chemical trace. The data show that long-lived, compositionally differentiated crustal reservoirs were established by 4.0–3.7 Ga and contributed substantially to felsic magmatism until ca 2.63 Ga. These signatures are preserved across multiple cratons worldwide.
The shift in the Neoarchaean
After 2.75–2.63 Ga the fingerprint largely vanishes from the record. Statistical change point analysis identifies this transition consistently in the full data compilation and in geographic and mineral-based subsets doi.org
Proceedings of the Royal Society A Mathematical Physical and Engineering Sciencesdoi.orgOpen source ↗.
The authors interpret the disappearance as evidence of a Neoarchaean transition to more efficient crustal recycling and of a reorganization of magma generation towards plate margins. The loss of long-lived fractionated crustal sources coincides with independent geological and compositional evidence of a late Archaean secular change in continental evolution.
Co-author Chris Kirkland described it as a transition from an early Earth where ancient crust could be repeatedly melted and reworked in place to a system able to move and recycle crust on a much larger scale. He noted that tectonic activity distinguishes Earth from planets such as Venus and Mars.
