Spatial Declustering of Zircon Data Indicate Rapid Archean Crustal Growth and Neoproterozoic Plate Tectonic Equilibrium

Abstract

The geochemical information stored in mineral zircon makes it widely used to document the formation and evolution of the continental crust. The physiochemical resilience of zircon enables precise isotopic dating even in scenarios where the zircon has experienced an array of multi-cycle geologic processes. The isotope information can be used to model the balance between the formation of new crust and the reworking of old crust throughout Earth's history. Previous models of continental crust growth relied on radiogenic isotope pairs, such as 176Lu/176Hf, but incorrectly formulated the spatiotemporal bias. This thesis presents a simple approach for spatiotemporal cluster correction using 19806 integrated U–Pb and Hf-isotope analyses of global detrital zircon compilation. The declustering algorithm is used to examine the representativeness of existing models and improve previous estimates of crustal evolution on regional and global scales. The new declustered modelling suggests faster continental growth during the Archean Eon and very little continental growth since the mid-Proterozoic. At around 1.0 to 0.7 Ga, the marked little to no net continental growth may be highlighted as the transition to mature modern-style tectonics. The distribution of crustal formation age estimated in this thesis serves as the lower limit to the true crustal growth, and the role of preservation bias and the degree of crustal destruction remains unknown.