The international team, led by Curtin's Timescales of Mineral Systems Group in the School of Earth and Planetary Sciences, worked with colleagues from the University of Gottingen and the University of Cologne to study zircon crystals preserved in ancient beach sands. Zircon is one of the most resilient minerals on Earth and can survive weathering, erosion and repeated transport through river and coastal systems over millions of years, making it a durable archive of surface processes.
Inside these zircon grains the team measured a rare noble gas, krypton, that is produced when minerals at Earths surface are bombarded by cosmic rays, high energy charged particles arriving from space. By quantifying cosmogenic krypton in individual zircon crystals, the researchers were able to determine how long the grains had remained near the surface before burial, effectively turning each grain into a time stamp that records rates of landscape evolution over vast timescales.
Lead author and Adjunct Curtin Research Fellow Dr Maximilian Drollner, who is also based at the University of Gottingen, said the new approach makes it possible to study landscapes much older than those accessible with conventional techniques. He noted that the method opens a window onto how Earths surface has responded to changing climate and tectonic forces through deep time.
"Our planets history shows climate and tectonic forces can control how landscapes behave over very long timescales," Dr Drollner said. "This research helps us understand what happens when sea levels change and how deep seated Earth movements influence the evolution of landscapes."
The study shows that when regions are tectonically stable and sea levels remain relatively high, erosion can slow dramatically. Under these conditions, sediments may be stored and reworked near the surface for millions of years, rather than being rapidly flushed offshore or buried, and the cosmogenic krypton signal in zircon captures this prolonged residence time.
Co author and Timescales of Mineral Systems Group lead Professor Chris Kirkland said the findings are relevant not only for reconstructing how Earths surface has evolved over billions of years, but also for planning and managing modern environments. As human activity modifies rivers, coastlines and continental shelves, the balance between sediment storage and removal is expected to shift, with long term consequences for landscape form.
"As we modify natural systems, we can expect changes in how sediment is stored in river basins and along coastlines and continental shelves," Professor Kirkland said. "Our results show that these processes can fundamentally reshape landscapes, not just coastlines, over time."
Associate Professor Milo Barham, also a co author from the Timescales of Mineral Systems Group, said the work has important implications for understanding and exploring Australias mineral resources. Because zircon and other durable minerals can withstand prolonged recycling, long periods of sediment storage help concentrate economically important heavy minerals while less robust material breaks down.
"Climate does not just influence ecosystems and weather patterns, it also controls where mineral resources end up and how accessible they become," Associate Professor Barham said. "Extended periods of sediment storage allow durable minerals to gradually concentrate while less stable materials break down, explaining why Australia hosts some of the worlds most significant mineral sand deposits."
The researchers argue that linking cosmogenic krypton signals with sediment transport and storage histories can improve models that predict how environmental change will alter sedimentary systems and the distribution of critical resources. That perspective is becoming increasingly important as demand grows for minerals used in advanced technologies and the energy transition.
The study, "Ancient landscape evolution tracked through cosmogenic krypton in detrital zircon," was published in the journal Proceedings of the National Academy of Sciences and presents the first large scale application of cosmogenic krypton in detrital zircon to map landscape evolution over geological timescales.
Research Report:Ancient landscape evolution tracked through cosmogenic krypton in detrital zircon
Related Links
Timescales of Mineral Systems Group
Explore The Early Earth at TerraDaily.com
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