Water‐Induced Mantle Overturns Leading to the Origins of Archean Continents and Subcontinental Lithospheric Mantle

Wu, Zhongqing; Song, Jian; Zhao, Guochun; Pan, Zhongxu

doi:10.1029/2023gl105178

Cited by 3 publications

(1 citation statement)

References 80 publications

(142 reference statements)

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“…The ρ and η of melts also affect the ability of crystals to float or sink, which significantly influences the crystallization of magmatic bodies. It is likely that the evolution of the mantle and continental crust in the early history of the Earth, such as in the Archean, might have been influenced by the ρ and η of melts (Wu et al., 2023).…”

Section: Introductionmentioning

confidence: 99%

Mobility of Magmas Within the Earth: Insights From the Elasticity and Transport Properties of Hydrous Albitic Melts

Ashley,

Bajgain,

Mookherjee

2024

Geochem Geophys Geosyst

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The continental crust is produced by the solidification of aluminosilicate‐rich magmas which are sourced from deep below the surface. Migration of the magma depends on the density (ρ) contrast to source rocks and the melt viscosity (η). At the surface, these silica‐rich melts are typically sluggish due to high η > 1,000 Pa s. Yet at their source regions, the melt properties are complexly influenced by pressure (P), temperature (T), and water contents (). In this study, we examined the combined P‐T‐ effects on the behavior of melts with an albite stoichiometry (NaAlSi3O8). We used first‐principles molecular dynamics simulations to examine anhydrous (0 wt % H2O) and hydrous (5 wt % H2O) melts. To constrain the P and T effects, we explored P ≤ 25 GPa across several isotherms between 2500 and 4000 K. The melts show anomalous P‐ρ relationships at low P ∼ 0 GPa and high T ≥ 2500 K, consistent with vaporization. At lithospheric conditions, melt ρ increases with compression and is well described by a finite‐strain formalism. Water lowers the melt density (ρhydrous < ρanhydrous) but increases the compressibility, that is, 1/Khydrous >1/Kanhydrous or Khydrous < Kanhydrous. We also find that the melt η decreases with pressure and then increases with further compression. Water decreases the viscosity (ηhydrous < ηanhydrous) by depolymerizing the melt structure. The ionic self‐diffusivities are increased by the presence of water. The decreased ρ and η by H2O increase the mobility of magma at crustal conditions, which could explain the rapid eruption and migration timescales for rhyolitic magmas as observed in the Chaitén volcano in Chile.

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Section: Introductionmentioning

confidence: 99%

Mobility of Magmas Within the Earth: Insights From the Elasticity and Transport Properties of Hydrous Albitic Melts

Ashley,

Bajgain,

Mookherjee

2024

Geochem Geophys Geosyst

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Successful subduction of oceanic plate after failed attempts in the Late Archean: Petrological and geochemical constraints

Wang,

Ge,

Zheng

et al. 2024

Earth and Planetary Science Letters

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Superionic iron hydride shapes ultralow-velocity zones at Earth’s core–mantle boundary

Zhang,

Wang,

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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Seismological studies have exposed numerous ultralow velocity zones (ULVZs) exhibiting extraordinary physical attributes at Earth’s core–mantle boundary, yet their compositions and origins remain controversial. Water–iron reaction can generate unique phases under lowermost-mantle conditions and likely plays a crucial role in forming ULVZs. Through first-principles molecular dynamic simulations with machine learning techniques, we determine that iron hydride, the product of water–iron reaction, is stable as a superionic phase at the core–mantle boundary. This superionic iron hydride has much slower velocities and a higher density than the ambient mantle under lowermost-mantle conditions. Accumulation of iron hydride, created through either a chemical reaction between subducted water and iron or solidification of core material entrained in the lower mantle by convection, can explain the seismic observations of ULVZs particularly those associated with subduction. This work suggests that water may have a substantial role in creating seismic heterogeneities at the core–mantle boundary.

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Water‐Induced Mantle Overturns Leading to the Origins of Archean Continents and Subcontinental Lithospheric Mantle

Cited by 3 publications

References 80 publications

Mobility of Magmas Within the Earth: Insights From the Elasticity and Transport Properties of Hydrous Albitic Melts

Mobility of Magmas Within the Earth: Insights From the Elasticity and Transport Properties of Hydrous Albitic Melts

Successful subduction of oceanic plate after failed attempts in the Late Archean: Petrological and geochemical constraints

Superionic iron hydride shapes ultralow-velocity zones at Earth’s core–mantle boundary

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