Cosmogenic krypton reveals ancient landscape evolution

by Robert Schreiber
Berlin, Germany (SPX) Jan 15, 2026
An international research team involving the University of Cologne has developed a new way to reconstruct how landscapes evolved tens of millions of years ago and to determine how long sediments remained at the Earth's surface before burial. The approach measures cosmogenic krypton, a rare noble gas produced when cosmic rays strike mineral grains at or near the surface, allowing scientists to quantify the time those grains spent exposed to radiation.

The study focuses on cosmogenic krypton preserved in zircon minerals extracted from sediment samples obtained in several drill cores from the Eucla Basin in southern Australia, one of the world's most important zircon deposits. By analysing tiny zircon grains for stable cosmogenic krypton isotopes and combining those data with established U Pb age determinations, the team can link the original formation age of the minerals with their subsequent surface exposure and transport history.

U Pb dating uses the natural radioactive decay of uranium to lead in resistant minerals such as zircon to determine when the crystals formed, often millions to billions of years ago. While these U Pb ages mainly reveal the source and original crystallization age of the zircon grains, the cosmogenic krypton concentrations provide a direct measure of how long the grains were exposed at or near the Earth's surface, and thus constrain transport, storage, and erosion processes over geological time scales.

The results show that some zircon grains remained at the surface for more than a million years before they were finally deposited in the sedimentary basin. The data reveal a shift from long stored, strongly weathered sediments formed under high global temperatures in the middle Eocene to more dynamic transport conditions with shorter residence times that followed, indicating a fundamental reorganization of surface processes.

This transition coincides with changes in sea level and tectonic activity, pointing to a close coupling between climate, tectonics, and sediment transport over millions of years. By tracking how cosmogenic krypton signatures vary through the stratigraphic record, the researchers can reconstruct phases of landscape stability and episodes of intensified erosion and sediment redistribution.

According to Professor Tibor J. Dunai of the University of Cologne's Institute of Geology and Mineralogy, the method developed in Cologne for measuring cosmogenic krypton in zircons allows scientists for the first time to quantitatively record the surface history of zircon bearing sediments in very old geological systems. Until now, similar studies were constrained by the relatively short half lives, on geological time scales, of other commonly used cosmogenic nuclides, which limited their utility for very ancient terrains.

In the long term, the cosmogenic krypton approach opens new perspectives for investigating old, tectonically stable continental regions whose landscape histories were previously difficult to quantify. The team expects that the method can be applied in other parts of the world to better understand how climate variations and environmental change have shaped the Earth's surface over tens of millions of years.

Research Report:Ancient landscape evolution tracked through cosmogenic krypton in detrital zircon