Quantifying the Timing and Rate of Crustal Evolution: Global Compilation of Radiometrically Dated Detrital Zircon Grains

Multiple models (steady state, episodic, and early growth followed by crustal reworking) have been postulated to explain the evolution of Earth's continental crust. An independent assessment of these models is now possible as a result of the massive numbers of detrital zircon grains that have been dated individually over recent years using U-Pb and Hf isotopes. A compilation of similar to 200,000 published zircon dates reveals a global age distribution (U-Pb) with six prominent, statistically significant peaks: 3.2-3.0, 2.7-2.5, 2.0-1.7, 1.2-1.0, 0.7-0.5, and 0.3-0.1 Ga. In most cases, these peaks are recorded on all seven continents. Most of the peaks are detectable also in modern sediments. A comparison of grains with both U-Pb ages and Hf isotope model ages, available for similar to 5100 detrital zircons, suggests that the age frequency distribution of detrital grains reflects predominantly episodic crustal recycling rather than crustal growth. The zircon age distributions and associated data provide consistent evidence for the episodic nature of the Earth's plate tectonics.