Seismic signals induced by the Metasomatism of mantle wedge by siliceous melts: Insights from the elasticity of orthopyroxene at high pressure and temperature

Deng, Xin; Song, Jian; Qian, Wangsheng; Wu, Zhongqing

doi:10.1016/j.tecto.2022.229681

Cited by 4 publications

(4 citation statements)

References 98 publications

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“…In this study, we used the method (Luo et al., 2021; Wu & Wentzcovitch, 2011; Zou et al., 2018) which only needs vibrational density of states of unstrained configurations and elastic tensors at static conditions to obtain the simultaneously high P‐T elasticities of minerals. This method which reduces the computational effort to one‐tenth of the conventional method has been applied to numerous minerals successfully (Deng et al., 2023; Hao et al., 2019; Wang et al., 2021; Wu & Wang, 2016; Yao et al., 2018; Zou et al., 2018). So we adopted the method to calculate the elasticity of CaMg(CO 3 ) 2 dolomite at high P‐T.…”

Section: Methodsmentioning

confidence: 99%

Is There a Carbonated Mid‐Lithosphere Discontinuity in Cratons?

Zhao,

Deng,

Chen

et al. 2024

JGR Solid Earth

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The mid‐lithosphere discontinuity (MLD), identified by a sharp velocity drop at ∼70–100 km depths within the cratonic lithosphere is key to comprehending the chemical composition and thermal structure of the cratonic lithosphere. The MLD is widely accepted to be caused by composition anomalies, such as hydrous minerals, which show low velocities and high electrical conductivities. However, noticeable high‐electrical conductivity anomalies have not been detected in the most cratonic lithosphere. Dolomite has an electrical conductivity similar to olivine and can be originated by carbonatitic melts trapped at ∼80–140 km depths. Here we investigated the elasticity of dolomite under mantle conditions using ab initio calculations and found dolomite exhibits significantly lower velocities than the primary minerals in the lithospheric mantle. Therefore, the dolomite enrichment might provide a good explanation for the observed velocity drop of the MLD in cratonic regions where no high‐conductivity anomaly has been detected, such as the northern Slave craton.

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Section: Methodsmentioning

confidence: 99%

Is There a Carbonated Mid‐Lithosphere Discontinuity in Cratons?

Zhao,

Deng,

Chen

et al. 2024

JGR Solid Earth

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“…This method only needs the VDos of the unstrained configuration to obtain high‐T elasticity, significantly reducing the computational workload to less than 10% of the conventional methods while maintaining high accuracy. This method has been applied successfully to many minerals (Deng et al., 2022, 2023; Duan et al., 2019; Hao et al., 2019; Z. J. Song et al., 2022; Wang et al., 2020; Wu & Wang, 2016; Zhao et al., 2022).…”

Section: Methodsmentioning

confidence: 99%

“…This method only needs the VDos of the unstrained configuration to obtain high-T elasticity, significantly reducing the computational workload to less than 10% of the conventional methods while maintaining high accuracy. This method has been applied successfully to many minerals (Deng et al, 2022(Deng et al, , 2023Duan et al, 2019;Hao et al, 2019;Wang et al, 2020;Wu & Wang, 2016;Zhao et al, 2022). Additionally, the phase boundary was determined by comparing the Gibbs free energy of the reactant and the product, which is directly deduced from F from…”

Section: Methodsmentioning

confidence: 99%

Elasticity of Anhydrous Phase B Under Mantle Conditions: Implications for the Deep X‐Discontinuity in the Subduction Zones

Song,

Wang,

2023

Geochem Geophys Geosyst

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Anhydrous phase B (anh‐B) is a dense magnesium silicate with the composition Mg14Si5O24 and space group Pmcb. In magnesium‐rich environments, forsterite reacts with periclase to form anh‐B, and the formation of anh‐B was proposed as a plausible mechanism for the origin of the X‐discontinuity. However, the elastic properties of anh‐B, which are critical for evaluating the seismic features associated with its formation, have not been determined. In this study, we investigated the elasticity of anh‐B at high pressure and temperature via first‐principles calculations. Combining with the elasticity of other minerals, we determined the contrasts caused by the formation of anh‐B: ∼3%, ∼7%, and ∼10% jumps for density, VP, and VS, respectively. The 2%–8% impedance contrasts of the X‐discontinuity can be explained by the formation of 15–60 vol% anh‐B, which requires 3–12 vol% MgO as a reactant.

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“…These liberated fluids can alter the composition of the overlying mantle wedge and reduce the melting point of mantle rocks, thereby potentially triggering arc magmatism 11,12 . Therefore, tracking the nature and fate of slab-released fluids is crucial to understanding mantle heterogeneity, arc magmatism, and the deep water cycle 1,4,9,[13][14][15] .…”

mentioning

confidence: 99%

Heavy magnesium isotopic signatures in arc lavas may be attributed to dehydration of subducting hydrated mantle

Deng,

Chen,

Wang

et al. 2024

Commun Earth Environ

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Fluids released from subducting slabs profoundly affect mantle composition, rock melting points, and arc magma generation. However, identifying fluid sources (sediments, crust, or mantle) and their ascent paths remains challenging. Magnesium isotopes are potential tracers for subduction-related fluids, though their behavior during hydrous peridotite dehydration remains unclear. Here we determined the equilibrium magnesium isotope fractionation factors between aqueous fluids and hydrous peridotitic minerals using first-principles calculations. Aqueous fluids prefer heavy magnesium isotopes relative to mantle silicate minerals, indicating that fluids released during hydrous peridotite dehydration are enriched in heavy magnesium isotopes relative to the residual minerals. Our simulations proposed that magnesium isotope variations in arc lavas from different subduction zones could be attributed to different dehydration reactions influenced by subduction zone thermal structures. This study highlights the potential of magnesium isotopes for tracing fluids originating from subducting hydrated mantle, providing insights into the thermal structure of various subduction zones.

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Seismic signals induced by the Metasomatism of mantle wedge by siliceous melts: Insights from the elasticity of orthopyroxene at high pressure and temperature

Cited by 4 publications

References 98 publications

Is There a Carbonated Mid‐Lithosphere Discontinuity in Cratons?

Is There a Carbonated Mid‐Lithosphere Discontinuity in Cratons?

Elasticity of Anhydrous Phase B Under Mantle Conditions: Implications for the Deep X‐Discontinuity in the Subduction Zones

Heavy magnesium isotopic signatures in arc lavas may be attributed to dehydration of subducting hydrated mantle

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