Single‐Crystal Elasticity of Phase E at High Pressure and Temperature: Implications for the Low‐Velocity Layer Atop the 410‐km Depth

Wang, Baoyun; Zhang, Yanyao; Fu, Suyu; Ding, Xing; Liang, Wen; Takáhashi, Eiichi; Li, Li; Tkachev, Sergey N.; Prakapenka, Vitali B.; Lin, Jung‐Fu; Song, Mo

doi:10.1029/2022jb025274

Cited by 3 publications

(3 citation statements)

References 98 publications

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“…Velocities of major mantle minerals and humite-group minerals at ambient conditions. Blue circles: major mantle minerals, including olivine (Mao et al, 2015), orthopyroxene (Li et al, 2022), clinopyroxene (Li and Neuville, 2010), wadsleyite (Mao et al, 2015), garnet (Wei et al, 2021), phase A (Cai et al, 2021;Sanchez-Valle et al, 2006), and phase E (Satta et al, 2019;Wang et al, 2022). Red circles: the F-bearing humite-group minerals reported in this study, including F 61 -chondrodite, F 37 -humite, F 8 -clinohumite, and F 45clinohumite.…”

Section: Figurementioning

confidence: 73%

“…In the Fe-free system, OHchondrodite displays the lowest sound velocities (V P =8.25(12) km/s and V S =4.76(12) km/s) within the humite-group minerals at ambient conditions. Despite these relatively low values within the humite-group minerals, the V P of chondrodite still exceeds that of Fe-free phase A by 2.9%, and its V P and V S are 5.8% and 4.6% higher than those of Fe-free phase E, respectively (Cai et al, 2021;Wang et al, 2022). Incorporation of Fe will lead to a reduction in both V P and V S of chondrodite, phase A, and phase E (Sanchez-Valle et al, 2006;Satta et al, 2019).…”

Section: Discussionmentioning

confidence: 95%

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Single-crystal elasticity of humite-group minerals by Brillouin scattering

Zhang,

et al. 2024

American Mineralogist

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Humite-group minerals play a crucial role in transporting water and fluorine to the Earth's deep mantle through slab sinking. In this study, we have used Brillouin scattering to determine the single-crystal elastic constants of four natural humite-group minerals with varying H 2 O and fluorite contents under ambient conditions, including one chondrodite [Mg 4.88 Si 1.94 O 8 (OH 0.78 F 1.22 )] (F 61 -Chn), one humite [Mg 7.03 Si 3.07 O 12 (OH 1.26 F 0.74 )] (F 37 -Hu), and two clinohumite [Mg 8.85 Ti 0.19 Si 3.93 O 16 (OH 1.11 F 0.89 ) and Mg 8.63 Fe 0.10 Ti 0.24 Si 3.97 O 16 (OH 1.84 F 0.16 )](F 45 -Chu and F 8 -Chu) samples. The adiabatic bulk (K S0 ) and shear (G 0 ) moduli calculated from the elastic constants using Voigt-Reuss-Hill averages are: K S0 = 120.4(3) GPa and G 0 = 74.1(5)GPa for F 61 -Chn, K S0 = 122.4(3) GPa and G 0 = 78.4(2) GPa for F 37 -Hu, K S0 = 126.2(3) GPa and G 0 = 79.7(2) GPa for F 45 -Chu, and K S0 = 120.5(3) GPa and G 0 = 76.8(2) GPa for F 8 -Chu. Our results indicate that the addition of F leads to a noticeable increase in the elasticity of clinohumite and chondrodite, which is in contrast to the effect of H 2 O. Although Fe has a negligible effect on the bulk modulus of clinohumite, it can produce a substantial decrease in the shear modulus. These results provide important insights into the influence of humite-group minerals on the mantle velocity structure. Furthermore, we have investigated the influence of composition on the elasticity and sound velocities of minerals along the forsterite-brucite join in the MgO-SiO 2 -H 2 O system, confirming previous observations. Increasing H 2 O content along the forsterite-brucite join leads to apparent reductions in the elasticity and sound velocities. The influence of Fe on the elasticity and sound velocities of these minerals has also been evaluated.

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Section: Figurementioning

confidence: 73%

Section: Discussionmentioning

confidence: 95%

Single-crystal elasticity of humite-group minerals by Brillouin scattering

Zhang,

et al. 2024

American Mineralogist

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“…The LVLs are characterised by thicknesses of 56-94 km and P-wave velocity drops of −2.8 to −4.7%. This cannot be explained by the phase transition of serpentine into dense hydrous magnesium silicate 35 , nor can it be explained by the phase transformation of olivine 36 . Similar LVLs are found worldwide [5][6][7][8][9][10][11][12][13][14][15] , and these results are usually explained as being caused by partial melting induced by water and/or other volatiles (i.e.…”

Section: Discussionmentioning

confidence: 98%

Upper mantle melt caused by a subducted slab in the Indian-Eurasian continental subduction zone

Li,

Zhou,

Bai

et al. 2023

Commun Earth Environ

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A low-velocity layer atop the mantle transition zone has been extensively observed worldwide. In subduction zones, this layer is widely explained as partial melting triggered by slab subduction on a regional or global scale. However, direct observational evidence is still absent, and the response of the layer to slab subduction is not well known. Here, we image the seismic velocity around the mantle transition zone by matching synthetic and observed triplicated seismic P and sP waveforms in the Indian–Eurasian continental subduction zone. Our observations reveal a laterally varied low-velocity layer atop the mantle transition zone beneath the Hindu Kush, where a subducted slab extends to the mantle transition zone. The geometric morphology of the low-velocity layer documents that it is a partially molten layer induced by the subducted slab on a regional scale. Interestingly, our observations also support that the layer has a low viscosity. The decreased viscosity may facilitate slab motion in the deep mantle, contributing to slab stretching, tearing and break-off and its resultant rare recurring large intermediate-depth earthquakes in an intracontinental setting.

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Elasticity of Single‐Crystal Clinohumite at High Pressures and Temperatures: Implication for the H₂O and F Circulation in the Earth's Mantle

Li,

Zhang,

et al. 2024

JGR Solid Earth

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In this study, we have determined the single‐crystal elasticity of clinohumite [Mg8.85Ti0.19Si3.93O16(OH1.11F0.89)] using Brillouin measurement up to 21 GPa at 300 K and 1 bar at 750 K, respectively. The elasticity of clinohumite was determined to be KS0 = 126.2(3) GPa, G0 = 79.7(2) GPa with pressure derivatives KS′ = 4.2(1), G′ = 1.3(1), pressure derivatives ∂KS/∂T = −0.024(1) GPa/K, and ∂G/∂T = −0.011(1) GPa/K). We comprehensively examined the effects of varying H2O, fluorine content and thermal states, on the velocity and density structures of the subducted harzburgite layer. Assuming a typical H2O content of 2 wt.% within harzburgite, our modeling has shown that hydrous harzburgite with clinohumite as the decomposition product of serpentine along a hot slab geotherm even has the VP and VS 0.4–0.8(6)% greater than it dry counterpart at 250–380 km depth. Yet in the top transition zone, the addition of H2O and F can effectively lower the sound velocities and density. The F‐bearing hydrous harzburgite has the VP and VS 1.1(5)–1.3(3)% lower than its dry counterpart, and only 0.6(5)% and 2.3(5)% greater than the pyrolitic mantle. Along cold slab geotherm, phase A will replace clinohumite as the dominant hydrous phase in the harzburgite, the VP and VS are 4.8(5)–5.3(3)% and 5.9(5)–6.0(3)% greater than the pyrolitic mantle in the upper mantle. In the top transition zone, the difference is approximately 3% in VP and 5% in VS. Our results provide crucial experimental evidence for future assessments of the seismic signals of subducted slabs with different hydrous minerals and thermal states.

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Single‐Crystal Elasticity of Phase E at High Pressure and Temperature: Implications for the Low‐Velocity Layer Atop the 410‐km Depth

Abstract: Table S1. Unit-cell parameters and volumes of phase E determined by XRD measurements at various P-T conditions.Run 1 ambient 300 2.968(1) 13.885(2)

Cited by 3 publications

References 98 publications

Single-crystal elasticity of humite-group minerals by Brillouin scattering

Single-crystal elasticity of humite-group minerals by Brillouin scattering

Upper mantle melt caused by a subducted slab in the Indian-Eurasian continental subduction zone

Elasticity of Single‐Crystal Clinohumite at High Pressures and Temperatures: Implication for the H₂O and F Circulation in the Earth's Mantle

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Single‐Crystal Elasticity of Phase E at High Pressure and Temperature: Implications for the Low‐Velocity Layer Atop the 410‐km Depth

Abstract: Table S1. Unit-cell parameters and volumes of phase E determined by XRD measurements at various P-T conditions.Run 1 ambient 300 2.968(1) 13.885(2)

Cited by 3 publications

References 98 publications

Single-crystal elasticity of humite-group minerals by Brillouin scattering

Single-crystal elasticity of humite-group minerals by Brillouin scattering

Upper mantle melt caused by a subducted slab in the Indian-Eurasian continental subduction zone

Elasticity of Single‐Crystal Clinohumite at High Pressures and Temperatures: Implication for the H2O and F Circulation in the Earth's Mantle

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Elasticity of Single‐Crystal Clinohumite at High Pressures and Temperatures: Implication for the H₂O and F Circulation in the Earth's Mantle