Continental crustal growth progressive model

Common to all crustal growth models is that simple cmstal extraction using the known amount of Early Archean cmst cannot readily account for the degree of depletion evident in some interpretations of the initial and enr compositions of the Archean mantle (Section 2.13.2). In the next sections, the effects of processes other than progressive growth of the continental cmst from a depleting mantle are considered. 

Taken together, the age data for crustal rocks, for which there is now a very extensive database, strongly support a progressive model for the growth of the continental crust. 

Their best-fit models are shown in Fig. 4.8 and support a progressive growth model for the continental crust, with about 50% crust formed by the end of the Archaean. Their calculations show that there was little crustal recycling before the mid-Proterozoic. 

---