| Autor: |
Mulder JA; School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia. jack.mulder@monash.edu., Nebel O; School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia., Gardiner NJ; School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia.; School of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom., Cawood PA; School of Earth, Atmosphere and Environment, Monash University, Clayton, VIC, Australia., Wainwright AN; School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, VIC, Australia., Ivanic TJ; Geological Survey of Western Australia, Department of Mines, Industry Regulation and Safety, East Perth, WA, Australia. |
| Abstrakt: |
The formation of stable, evolved (silica-rich) crust was essential in constructing Earth's first cratons, the ancient nuclei of continents. Eoarchaean (4000-3600 million years ago, Ma) evolved crust occurs on most continents, yet evidence for older, Hadean evolved crust is mostly limited to rare Hadean zircons recycled into younger rocks. Resolving why the preserved volume of evolved crust increased in the Eoarchaean is key to understanding how the first cratons stabilised. Here we report new zircon uranium-lead and hafnium isotope data from the Yilgarn Craton, Australia, which provides an extensive record of Hadean-Eoarchaean evolved magmatism. These data reveal that the first stable, evolved rocks in the Yilgarn Craton formed during an influx of juvenile (recently extracted from the mantle) magmatic source material into the craton. The concurrent shift to juvenile sources and onset of crustal preservation links craton stabilisation to the accumulation of enduring rafts of buoyant, melt-depleted mantle. |
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