A whole-lithosphere view of continental growth

Abstract

Methods Previous Crustal Growth Estimates Previous crustal growth estimates calculated by Dhuime et al., (2012; 2017) are here collectively referred to as D27 and these widely used crustal growth curves are based on a modification of the calculations of Belusova et al. (2010). In the calculation scheme used by D27, an age spectrum was obtained by compiling zircon Hfisotope depleted mantle model extraction ages. Each individual zircon U-Pb + Hf isotope data point was used to calculate a depleted mantle model extraction age, and these model ages were binned across geologic time. This age distribution was corrected for reworking using a modification of the methods employed by (Belousova et al., 2010). Instead of considering only zircon Hf isotope data, D27 used zircon O-isotope data to identify crustal reworking signals in the zircon record where zircon oxygen isotope values above the mantle range were considered to be evidence of a reworking signal. A curve proposed to be the crustal growth rate was calculated by determining the relationship between crustal reworking – identified using zircon Hf isotope model ages – and juvenile crustal growth – identified using O-isotope ratios. These calculations are replicated in Supplementary Table S-2. However, there is a flaw in the calculations employed in the D27 work (as pointed out by (Korenaga, 2018)).