The depleted mantle reservoir is that part of Earth's mantle from which crust has been extracted, leaving the remaining mantle depleted in incompatible elements. Knowing how and when it formed is essential for understanding the chemical evolution of Earth, including formation of continental crust. The best-constrained Hf isotope data presented here indicate that the mantle does not become significantly depleted until as late as 700 million years after Earth's accretion. This onset of mantle depletion coincides with the first appearance of substantial volumes of continental crust in the geological record. These data compel a revision to the reference depleted mantle parameters used in Hf isotope studies of planetary evolution. This new reference line follows chondritic evolution until 3.8 Ga and then describes a linear trajectory to a present-day depleted mid-ocean ridge basalt source mantle composition (ε Hf = +18). We infer that stabilization of continental crust only occurred in earnest on Earth after 3.8 Ga. ▪ Hf isotopes show that Earth's mantle does not become significantly depleted until 700 million years after planetary accretion. ▪ Most of Earth's oldest rocks formed from mantle sources that had radiogenic isotope compositions similar to those of chondritic meteorites. ▪ Isotope evidence shows that Hadean (&gt;4.0-billion-year-old) crust was not essential for formation of younger crust in Archean terranes. ▪ Growth of Earth's continents only began in earnest after 3.8 Ga.

Jeffrey D. Vervoort

Anthony I.S. Kemp

Annual Review of Earth and Planetary Sciences

自 1973 年出版的《地球与行星科学年度回顾》涵盖了地球和行星科学所有领域的重大发展，从气候、环境和地质灾害到行星的形成和生命的进化。

The Annual Review of Earth and Planetary Sciences has been published since 1973, covering significant developments in all areas of Earth and planetary sciences, including climate change, environmental issues, geological hazards, planetary formation, and the evolution of life.

《Annual Review of Earth and Planetary Sciences》自1973年出版，涵盖了地球与行星科学各个领域的重要进展，包括气候变化、环境问题、地质灾害、行星形成以及生命的演化等。

Category	Quartile
地球科学	1
地球科学, 天文与天体物理	1
地球科学, 地球科学综合	1

Isotope Evolution of the Depleted Mantle

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Journal Info

Category	Quartile
GEOSCIENCES, MULTIDISCIPLINARY	1