| Summary: | Detrital zircons from the Ob, Yenisey, Lena, Amur, Volga, Dnieper, Don and Pechora rivers have been analyzed for U–Th–Pb, O and Lu–Hf isotopes to constrain the growth rate of the preserved continental crust in Greater Russia. Four major periods of zircon crystallization, 0.1–0.55, 0.95–1.3, 1.45–2.0 and 2.5–2.9 Ga, were resolved from a compilation of 1366 zircon U/Pb ages. The Archean zircons have δ 18 O values lying between 4.53‰ and 7.33‰, whereas Proterozoic and Phanerozoic zircons have a larger range of δ 18 O values in each of the recognized U/Pb time intervals with maximum δ 18 O values up to 12‰. We interpret the zircons with δ 18 O between 4.5‰ and 6.5‰ to have been derived from a magmatic precursor that contains little or no sedimentary component. The variable δ 18 O values of the zircons were used to constrain the 176 Lu/ 177 Hf ratios of the crustal source region of the zircons, which, in turn, were used to calculate Hf model ages (T DM V ). The crustal incubation time, the time difference between primitive crust formation (dated by T DM V ) and crustal melting (dated by zircon U/Pb age), varies between 300 to 1000 Myr for the majority of analyzed zircon grains, but can be up to 2500 Myr. The average T DM V Hf model age weighted by the fraction of zircons in the river load is 2.12 Ga, which is in reasonable agreement with the area-weighted average of 2.25 Ga. The T DM V Hf model age crustal growth curve for zircons with mantle-like δ 18 O values (4.5–6.5‰), weighted by area, shows that growth of the Great Russian continental crust started at 4.2 Ga, and that there are two principal periods of crustal growth, 3.6–3.3 Ga and 0.8–0.6 Ga, which are separated by an interval of low but more or less continuous growth. An alternative interpretation, in which the average 176 Lu/ 177 Hf ratio (0.0115) of the continental crust is used for the Paleoproterozoic zircons from the Lena River, lowers the average T DM V age of these grains by about 500 Myr and delays the onset of significant crustal growth to 3.5 Ga. ...
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