A zircon petrochronologic view on granitoids and continental evolution

peer reviewedTemporal trends in granitoid chemistry and thermometry constrain major global changes in magmatism, tectonism or crustal thickness in the continents. Our study relies on zircon geochronology and trace element geochemistry on four new detrital rocks (two modern sediments and two Archean metasedimentary rocks) and a global compilation of published single zircon detrital chronology and trace chemistry data acquired on 5587 individual grains. Zircons of all ages from 4.4 Ga to present exist in this archive. Ti-in-zircon thermometry indicates that more than 98% of the grains with concordant U-Pb ages formed at temperatures exceeding 650 °C. The great majority of these zircons formed in the 650–850 °C range consistent with growth in intermediate to silicic magmas. Magmatic temperatures increased over time for the first 1.2 Ga of Earth's history after which they stayed constant before decreasing during the more recent past. U/Th