Geoscience frontiers最新文献

{"title":"Constraints on the spin-state transition of siderite from laboratory-based Raman spectroscopy and electrical conductivity under high temperature and high pressure","authors":"Xinyu Zhang ,&nbsp;Lidong Dai ,&nbsp;Haiying Hu ,&nbsp;Meiling Hong ,&nbsp;Chuang Li","doi":"10.1016/j.gsf.2024.101918","DOIUrl":"10.1016/j.gsf.2024.101918","url":null,"abstract":"<div><div>The vibrational and electrical transport properties of natural siderite are systematically investigated by means of <em>in-situ</em> Raman spectroscopy and alternating current impedance spectroscopy under conditions of 0.6–55.6 GPa, 298–873 K and different hydrostatic environments using a diamond anvil cell (DAC). Upon non-hydrostatic compression, all of these observable characteristic variations of siderite including the appearance of three absolutely new Raman peaks (<em>L</em>’, <em>v</em>₄′ and <em>v</em>₁′), the disappearance of Raman peaks (<em>T</em>, <em>L</em> and <em>v</em>₄) and the discontinuity in the pressure-dependent electrical conductivity can provide robust evidence of electronic spin transitions of Fe²⁺ from high-spin to mixed-spin to low-spin states at the respective pressures of 42.5 GPa and 48.5 GPa. As far as hydrostatic condition, the electronic spin states from high-spin to mixed-spin to low-spin states occurred at the higher pressures of 45.7 GPa and 50.4 GPa, respectively, which implied the highly sensitive hydrostaticity of electronic spin transition pressures. Upon decompression, the reverse electronic spin transitions from low-spin to mixed-spin to high-spin states were detected at the respective pressures of 47.2 GPa and 28.7 GPa under non-hydrostatic condition, and as well as at the pressures of 49.4 GPa and 25.1 GPa under hydrostatic condition, respectively. The huge pressure hysteresis of 13.8 GPa and 20.6 GPa for the electronic spin state transition was revealed under non-hydrostatic and hydrostatic environments, respectively. In order to explore the effect of temperature on the electronic spin transition, a series of electrical conductivity experiments on siderite were performed over the temperature range of 323–873 K under conditions of three typical pressures of 47.7, 49.8 and 51.6 GPa. Furthermore, the functional relationships between the temperature and pressure describing the high-spin to mixed-spin to low-spin transitions for siderite were successfully established: <em>P</em>₁ (GPa) = 39.318 + 0.015 <em>T</em> (K) and <em>P</em>₂ (GPa) = 41.277 + 0.018 <em>T</em> (K), respectively. In conclusion, our acquired phase diagram of the electronic spin transition on siderite is beneficial to deep insight into the electronic spin behavior for those of iron-bearing carbonate minerals under high-temperature and high-pressure conditions.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101918"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elasticity of epidote at high pressure and its implications for the velocity anomaly in subduction zone","authors":"Junsheng Ma,&nbsp;Nao Cai,&nbsp;Duojun Wang","doi":"10.1016/j.gsf.2024.101933","DOIUrl":"10.1016/j.gsf.2024.101933","url":null,"abstract":"<div><div>Hydrous minerals play a critical role in modifying the physical and chemical properties of the Earth’s interior. Among those, epidote is an important hydrous mineral in greenschist and blueschist phases of the metamorphosed subducting crust at shallow depth (30-60 km). Here, we measured the compressional (<em>P</em>) and shear (<em>S</em>) wave velocities of a polycrystalline epidote sample at pressures up to 7 GPa and room temperature by means of ultrasonic interferometry. The obtained sound velocities and elastic moduli of epidote increase monotonically with pressure. Finite strain analysis on those data set yielded the elastic moduli and their pressure derivatives of epidote at ambient condition as follows: <span><math><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>S</mi><mn>0</mn></mrow></msub><mo>=</mo><mn>115.2</mn><mspace></mspace><mi>GPa</mi></mrow></math></span>, <span><math><mrow><msub><mrow><mi>G</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mn>66.7</mn><mspace></mspace><mi>GPa</mi></mrow></math></span>, <span><math><mrow><msubsup><mi>K</mi><mrow><mi>s</mi></mrow><mo>′</mo></msubsup><mo>=</mo><mn>4.6</mn></mrow></math></span>, <span><math><mrow><msup><mrow><mi>G</mi></mrow><mo>′</mo></msup><mo>=</mo><mn>1.1</mn></mrow></math></span>. Using the elastic properties of epidote, we set up a model to better understand the velocity jumps in the subducted oceanic crusts concerning the blueschist-eclogite transition at 60-90 km depths. Our results indicate that the calculated <em>P</em> and <em>S</em> wave velocity jumps are in good agreement with those seismic observations in the typical subduction zones such as northeastern Japan and southwestern Japan. The eclogitization from epidote bearing blueschist may provide an explanation for the wave velocity anomalies occurred in those regions.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101933"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of antigorite dehydration on velocity structure and water migration in subduction zones","authors":"Huan Zeng,&nbsp;Maining Ma,&nbsp;Yongbing Li,&nbsp;Jialei Zhang,&nbsp;Hao Guan,&nbsp;Xiao Li","doi":"10.1016/j.gsf.2024.101923","DOIUrl":"10.1016/j.gsf.2024.101923","url":null,"abstract":"<div><div>The water migration in subduction zones, primarily driven by the phase transition in hydrous minerals, can give rise to hydrated regions with reduced velocity. A fundamental element in comprehending and deciphering these low-velocity zones revolves around acquiring insights into the stability and elasticity of relevant hydrous minerals. As one of the main water carriers in shallow areas, antigorite can dehydrate to form talc, forsterite, and fluid (talc–bearing peridotites) in deep areas of subduction zones, and then the talc thus serves as one of the minerals that can bring water to the deep Earth. Here, the elasticity of talc up to 24 GPa and forsterite up to 12 GPa are calculated by using the first principles method. The result supposes that the talc structure transforming from talc I to talc II is at a pressure between 6 GPa and 8 GPa, impacting the trend of elastic wave velocity in response to pressure. Furthermore, the elastic wave velocity of forsterite can be significantly affected by iron concentration. Meanwhile, a variation velocity model with antigorite consumption and talc content is set up for talc-bearing serpentinized peridotite based on the elastic properties of talc and forsterite in this study, and antigorite in Wang et al. (2022). The results of our model demonstrate a decrease in the low-velocity anomaly in subduction zones, particularly in deep regions or areas with higher initial serpentinization degrees. The results also suggest that the mode of antigorite dehydration can diminish the estimation of water content transported to depths of subduction zones, such as the Mariana Trench and Northern Japan subduction zones. The mode of antigorite dehydration thus provides a useful tool for constraining the composition, seismic velocity structure, and water migration in subduction zones.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101923"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxygen fugacity-mediated carbonate reactions with siliceous fluids in shallow subduction zones","authors":"Fengxia Sun ,&nbsp;Jun Hu ,&nbsp;Weibin Gui ,&nbsp;Ao Deng ,&nbsp;Penghui Sun ,&nbsp;Fahui Xiong ,&nbsp;Jin Liu","doi":"10.1016/j.gsf.2024.101891","DOIUrl":"10.1016/j.gsf.2024.101891","url":null,"abstract":"<div><div>Sediments are one of the main carbon sinks in subduction zones, with CaCO₃ and SiO₂ being the main components in sediments. Their chemical stability plays a significant role in the form of carbon in the Earth’s mantle. Here we report the reactions of CaCO₃ with SiO₂ in hydrated sediments at 0.8–2.0 GPa, 400–500 ℃ and redox-buffered conditions relevant to shallow subduction zones. Our results show that the reaction CaCO₃ + SiO₂ = CaSiO₃ + C + O₂(fluid) occurs under CoCoO and IW buffered conditions to generate wollastonite (CaSiO₃) and carbonaceous material (CM). Moreover, wollastonite is formed by the dissolution-crystallization process, which may be significantly affected by oxygen fugacity, leading to distinct crystallization habits (<span><span>Yui, 1966</span></span>, <span><span>Schott et al., 2012</span></span>). Anhydrous experiments indicate that the reaction proceeds only in the presence of H₂O within the pressure and temperature (P-T) range of this study. The reaction occurs more rapidly with aragonite-structured than calcite-structured CaCO₃. Further, the experiment buffered with natural olivine at 1.0 GPa and 400 ℃ proves that the above reaction can occur during serpentinization processes in shallow subduction zones. More importantly, nanoscale CM may be generated under relatively reducing conditions, exhibiting Raman characteristics of kerogen. These results provide new insights into how deep carbon is distributed in the Earth’s interior.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101891"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141692311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stabilizing inverse ringwoodite with defects, and a possible origin for the 560-km seismic discontinuity","authors":"Xuwei Zhao ,&nbsp;Joshua M.R. Muir ,&nbsp;Mingda Lv ,&nbsp;Zhigang Zhang ,&nbsp;Xinjian Bao ,&nbsp;Xi Liu","doi":"10.1016/j.gsf.2024.101896","DOIUrl":"10.1016/j.gsf.2024.101896","url":null,"abstract":"<div><div>Ringwoodite is an important mineral in the mantle transition zone, and its cationic disorder can profoundly affect its physicochemical properties, but there is currently much controversy about this disorder. In this study, we investigate the cation disorder states of pure Mg₂SiO₄-ringwoodite and defective ringwoodite under mantle transition zone conditions through DFT calculations and thermodynamic models. Two stable endmembers are seen, one with normal ringwoodite structure and the other with inverted structure (its Si atoms and half of its Mg atoms have swapped sites). Our results indicate that pure ringwoodite does not invert (swap Mg and Si cations) under normal mantle temperatures but the introduction of a Si-excess, Mg-deficient defect induces a swap at normal mantle temperatures and this swap is likely induced by a wide range of defects including water. Thus, in the presence of such a defect or similar defects the olivine phase transition sequence may then go from olivine to wadsleyite to inverse ringwoodite, and then normal ringwoodite. We calculate the seismic properties of normal and inverse ringwoodite and find significantly slower wave speeds in inverted ringwoodite. Due to this difference the presence of inverse ringwoodite may provide a potential explanation for the discontinuous interface of seismic waves at the depth of ∼560 km.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101896"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141848931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compressional and shear wave velocities of Fe-bearing silicate post-perovskite in Earth’s lowermost mantle","authors":"Jing Yang ,&nbsp;Suyu Fu ,&nbsp;Jin Liu ,&nbsp;Jung-Fu Lin","doi":"10.1016/j.gsf.2024.101915","DOIUrl":"10.1016/j.gsf.2024.101915","url":null,"abstract":"<div><div>The bridgmanite (Bgm) to silicate post-perovskite (PPv) phase transition is believed to be the main cause for the distinct seismic features observed in the D'' layer, the lowermost region of the Earth’s mantle. However, the transition depth and elasticity of the PPv phase have been highly debated, as the chemical complexity within the D'' layer can largely affect the Bgm-PPv transition pressure and the associated velocity contrast. Experimental measurements of sound velocities for PPv with different chemical compositions under relevant lowermost-mantle conditions are essential but remain limited. In this study, we have reliably measured both compressional wave velocity (<em>V_P</em>), shear wave velocity (<em>V_S</em>), and density, for two Fe-bearing PPv compositions [(Mg_0.85Fe_0.15)SiO₃ and (Mg_0.75Fe_0.25)SiO₃] at lowermost mantle pressures using Impulsive Stimulated Light Scattering (ISS), Brillouin Light Scattering (BLS), and X-ray Diffraction (XRD) in diamond anvil cells. Our results indicate that the velocities of Fe-bearing PPv at 120 GPa can be described by the following relationships: <em>V_S</em> (km/s) = 7.65–2.8<em>X_Fe</em> and <em>V_P</em> (km/s) = 14.11–3.8<em>X_Fe</em>, where <em>X_Fe</em> represents mole fraction of the Fe content. The variations in the Fe content of PPv may provide one of the explanations for the seismic lateral variations observed at the Earth’s core mantle boundary. By comparing our results with the high-pressure velocities of Bgm, our velocity model suggests significant discontinuities across the Bgm-PPv transition, characterized by a reduction in both <em>V_P</em> and <em>V_Φ</em>, and an increase in <em>V_S</em>. These findings highlight the importance of considering the influence of chemical composition, particularly Fe content which could vary significantly at the D'' region, on the seismic properties of the PPv phase. The observed velocity contrasts across the Bgm-PPv transition may contribute to the complex seismic signatures observed in the D'' layer, underscoring the potential role of this phase transition in interpreting the seismic features of the lowermost mantle region.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101915"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A first-principles molecular dynamics study of molecular hydrogen diffusion in Fe-free olivine","authors":"Haibo Liu ,&nbsp;Baohua Zhang ,&nbsp;Hongzhan Fei ,&nbsp;Lei Liu","doi":"10.1016/j.gsf.2024.101926","DOIUrl":"10.1016/j.gsf.2024.101926","url":null,"abstract":"<div><div>Molecular hydrogen (H₂) may be an important form of water in nominally anhydrous minerals in the Earth’s mantle and plays a critical role in mantle water cycle, but the transport properties of H₂ remain unclear. Here, the diffusion of H₂ in Fe-free olivine lattice is investigated at pressures of 1–13 GPa and temperatures of 1300–1900 K by first-principles molecular dynamics. The activation energy and activation volume for H₂ diffusion in Fe-free olivine are determined to be 55 ± 8 kJ/mol and 3.6 ± 0.2 cm³/mol, respectively. H₂ diffusion in Fe-free olivine is faster than H⁺ by 1–4 orders of magnitude and therefore it is more favorable for hydrogen transportation under upper mantle conditions. H₂ can be carried to the mantle transition zone by subducting slabs without releasing to the surrounding mantle. The upper mantle may act as a lid, preventing the releasing of H₂ produced in the deep mantle to the surface.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101926"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A first-principles study of helium diffusion in aragonite under high pressure up to 40 GPa","authors":"Yu Huang ,&nbsp;Mingqiang Hou ,&nbsp;Hong Liu","doi":"10.1016/j.gsf.2024.101931","DOIUrl":"10.1016/j.gsf.2024.101931","url":null,"abstract":"<div><div>Helium diffusion in carbonates under mantle pressure is crucial for understanding thermal and chemical evolution of mantle. Based on the density functional theory (DFT) and the the climbing image nudged elastic band (CI-NEB) method, we performed first-principles calculations of diffusion characteristics of helium in perfect aragonite crystal under high pressure to 40 GPa. Our results show that He diffusion behaviors are controlled by pressure, temperature and crystal size. The activation energy increases, and the diffusion coefficients decrease significantly under high pressure. E_a[1<!--> <!-->0<!--> <!-->0] increases from 176.02 kJ/mol to 278.75 kJ/mol, and E_a[0<!--> <!-->0<!--> <!-->1] increases from 195.89 kJ/mol to 290.43 kJ/mol, with pressure increasing from 20 GPa to 40 GPa. At 700 K, the diffusion coefficients at 40 GPa is 7 orders of magnitude lower than that at 20 GPa; and at 1000 K it decrease 5 orders of magnitude. To ensure that at least 90% helium is not lost, we synthesized the temperature obtained from cooling and heating processes and derive the 'stable temperature range' for helium in aragonite. The obtained results show that the stable temperature range is 22–76 ℃ at 0 GPa and 641–872 °C at 40 GPa, for the crystal of 100–2000 μm size. Besides, the travel time of helium in aragonite under high pressure increases rapidly with pressure increasing. Our calculations indicate that helium can be quantitatively retained in aragonite in the deep mantle as long as the temperature is in the 'stable temperature range'. These results have certain implications for exploring the evolution of mantle and the storage of helium within it.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101931"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equation of state and thermodynamic properties of liquid Fe-O in the Earth’s outer core","authors":"Miaoxu Xie ,&nbsp;Jie Fu ,&nbsp;Anatoly B. Belonoshko","doi":"10.1016/j.gsf.2024.101847","DOIUrl":"10.1016/j.gsf.2024.101847","url":null,"abstract":"<div><div>Equation of state (EoS) plays a crucial role in the prediction of the composition of the outer core. Here, we calculated pressure (<em>P</em>)-volume (<em>V</em>)-temperature (<em>T</em>) data of liquid iron-oxygen alloys (Fe-<em>X</em> wt.% O, <em>X</em> = 0, 2.8, 6.1, and 9.9) under the outer core conditions (∼136–330 GPa, 4000–6000 K) by first-principles molecular dynamics simulations. We established an EoS for liquid Fe-O alloys with parameters including <em>P</em>, <em>T</em>, <em>V</em>, and O concentrations. Consequently, thermodynamic properties of liquid Fe-O alloys such as density (<em>ρ</em>), thermal expansion coefficient, isothermal and adiabatic bulk modulus, and sound velocity (<em>V_P</em>) are calculated. To constrain the O content, we predicted the <em>ρ</em>-<em>P</em> and <em>V_P</em>-<em>P</em> profiles along the geotherm and compared them with data from the Preliminary Reference Earth Model (PREM). We conclude that the adiabatic <em>T</em> profile as a function of depth affects the prediction of O content dramatically. With several anchored <em>T</em>_ICB, the composition of Fe-6.1 wt.% O matches the PREM data with an acceptable range of error. But strictly speaking, the distribution in the outer core is probably uneven. In such case, we state that the O content in the outer core cannot be higher than approximately 6.1 wt.%.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101847"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140771491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscosities of hcp iron alloys under Earth’s inner core conditions","authors":"Yunfan Xu ,&nbsp;Yu He ,&nbsp;Shichuan Sun ,&nbsp;Wei Zhang ,&nbsp;Weiru Dai ,&nbsp;Duck Young Kim ,&nbsp;Heping Li","doi":"10.1016/j.gsf.2024.101935","DOIUrl":"10.1016/j.gsf.2024.101935","url":null,"abstract":"<div><div>Viscosity is critical for controlling the dynamics and evolution of the Earth’s inner core (IC). The viscosities of hexagonal close-packed (hcp) and body-centred cubic (bcc) Fe were studied experimentally and theoretically under Earth's core conditions. However, Earth’s inner core is mainly composed of Fe-Ni alloys with some light element impurities (Si, S, C, H, O), and the influence of impurities (Ni, Si, S, C, H, and O) on viscosity is still unknown. In this study, the diffusion coefficients of Fe, Ni, Si, S, C, H, and O were calculated under IC conditions using ab initio molecular dynamics (AIMD) and deep learning molecular dynamics (DPMD) methods. Among them, C, H, and O are highly diffusive like liquids in the lattice, while Fe, Ni, Si, and S diffuse through Fe site vacancies. In binary alloys, the influence of these impurities (Ni: 12.5%, S: 3.6%, Si: 3.1%, C: 1.3%, O: 1.7%, H: 0.4% by weight) on viscosity is insignificant. Based on the dislocation creep mechanism, the predicted viscosities of the hcp Fe alloys are 1 × 10¹⁴–2 × 10¹⁶ Pa·s, which is consistent with the values predicted by free inner core nutation and seismic wave attenuation observations.</div></div>","PeriodicalId":12711,"journal":{"name":"Geoscience frontiers","volume":"16 1","pages":"Article 101935"},"PeriodicalIF":8.5,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143172718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}