Accretionary orogens are major sites of generation of continental crust but the specific spatial andtemporal distribution of crustal growth within individual orogens remains poorly constrained.Paleozoic(～550–270Ma)granitic rocks from the Alati,Junggar and Tianshan segments of the Central Asian OrogenicBelt(CAOB)have Nd–Hf isotope ratios that vary in space and time and are taken to reflect variable rates ofcrustal addition within a long-lived convergent plate setting.The Junggar segment is characterised by high anduniform Nd–Hf isotope ratios and it appears to have formed in an intra–oceanic arc system.
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