Geochemical Evolution of Early Earth's Mantle

The mantle of the early Earth underwent a series of profound chemical transformations driven by high‐temperature melting, core formation and progressive convective stirring. Initially, a global magma ocean crystallised to form buoyant mineral phases and residual melts, establishing the first major chemical layering. Metal–silicate differentiation during core segregation removed siderophile elements from the silicate shell, leaving distinct radiogenic isotope signatures that persist in modern mantle domains. As the mantle cooled, partial melting generated primitive crustal rocks such as komatiites and proto‐crustal ensembles, while nascent plate‐like motions or episodic overturns recycled surface materials into the deep mantle. Subduction of altered oceanic lithosphere introduced isotopically light components and volatiles, fostering long‐lived heterogeneity. Radiogenic systems (for example ¹⁴²Nd/¹⁴⁴Nd, ¹⁸²W/¹⁸⁴W, ¹⁴⁶Sm–¹⁴²Nd) record this interplay between early differentiation, crustal extraction and convective homogenisation. Through time, vigorous mantle stirring reduced isotopic contrasts, but ancient reservoirs remain detectable, offering a window onto processes that shaped the silicate Earth’s structure, thermal evolution and resource endowment.

Research from Nature Portfolio

Oxygen isotope analyses of 3.27-billion-year-old komatiites reveal two mantle sources distinguished by δ¹⁸O and Mg-rich olivine compositions. One group exhibits modern mantle‐like values, while the other shows lower δ¹⁸O consistent with recycled altered oceanic crust, indicating that subduction processes were active by 3.3 Ga and contributed to deep mantle heterogeneity.

Neodymium isotope studies of Paleoarchean rocks demonstrate that a depleted mantle reservoir differentiated as early as 4.19 billion years ago. This Hadean depletion event is mirrored in the hafnium isotopic signature of ancient zircons and implies pulses of large‐scale magmatism and crustal rejuvenation during Earth’s first half-billion years.

High‐precision ¹⁸²W isotope measurements in 2.7 Ga banded iron formations track variable fluxes of tungsten from continental and hydrothermal mantle sources into seawater. Alternating Si-rich and Fe-rich bands record contrasting crustal and mantle inputs, offering a dual chronicle of crust–mantle evolution through deep time.

Geochemical Evolution of Early Earth's Mantle publication trend

The graph below shows the total number of articles in geochemical evolution of early earth's mantle across all publications each year (not limited to Nature Index journals).

Technical terms

Komatiite: An ultra-mafic volcanic rock formed by very high-temperature mantle melting in the Archean.

Radiogenic isotope system: A decay-based chronology tool using parent-daughter ratios (e.g. ¹⁴²Nd/¹⁴⁴Nd, ¹⁸²W/¹⁸⁴W) to date and trace differentiation.

Magma ocean: A global or regional layer of molten silicates on the early Earth that crystallised to form primordial mantle layering.

Partial melting: Process by which only a portion of mantle rock melts, producing magmas with distinct chemical compositions.

Subduction: The descent of oceanic lithosphere into the mantle, recycling crustal and hydrous components into deep reservoirs.

Protocrust: The earliest continental crust formed from high-degree mantle melts during the Hadean eon.

References

1. Light oxygen isotopic composition in deep mantle reveals oceanic crust subduction before 3.3 billion years ago. Communications Earth & Environment (2024).
2. Tungsten stable isotope composition of the upper continental crust. Geochimica et Cosmochimica Acta (2024).
3. Earth’s geodynamic evolution constrained by 182W in Archean seawater. Nature Communications (2022).
4. Long-term preservation of Hadean protocrust in Earth’s mantle. Proceedings of the National Academy of Sciences of the United States of America (2022).