Physics of the Earth and Planetary Interiors最新文献

{"title":"Crustal shear-wave velocity structure of the Namche Barwa massif, eastern Himalayan Syntaxis, Tibet from ambient noise tomography","authors":"Jiawei Tan ,&nbsp;Xuzhang Shen ,&nbsp;Siyuan Cheng ,&nbsp;Rui Gao ,&nbsp;Wentian Wang","doi":"10.1016/j.pepi.2025.107363","DOIUrl":"10.1016/j.pepi.2025.107363","url":null,"abstract":"<div><div>The eastern termination of the Himalayan orogeny, known as Namche Barwa, serves as a crucial natural laboratory for geodynamic studies of the Tibetan Plateau due to its distinctive geological and geomorphological characteristics. To enhance the understanding of regional tectonics, we deployed a dense array of 374 short-period geophones from June to July 2020 to record continuous waveforms. Using vertical-component data, we computed cross-correlation functions and extracted 13,466 Rayleigh wave phase-velocity dispersion curves for periods ranging from 0.8 to 8 s. We applied the direct surface wave tomography method to invert the three-dimensional shear-wave velocity structure at depths of 0–6 km in the region. Our results reveal that the shallow crustal velocity structure in this region exhibits significant lateral heterogeneity, reflecting the complexity of the geological units. Low-velocity anomalies are primarily observed near faults, including the Indus-Yarlung Suture Zone and the Jiali Fault, while a high-velocity anomaly is detected beneath the Namche Barwa massif. In combination with previous geophysical studies, including magnetotelluric (MT) and seismic imaging results, this high-velocity anomaly is speculated to reflect the intrusion of deep crustal material into the shallow crust. The spatial correlation between the velocity model and seismicity distribution suggests that earthquakes are closely associated with local stress conditions, velocity structure, and the presence of aqueous fluids and geothermal anomalies.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107363"},"PeriodicalIF":2.4,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variations in mantle flow beneath the Eastern Himalaya inferred from shear wave splitting","authors":"Arti Devi ,&nbsp;Sunil K. Roy ,&nbsp;Jyotima Kanaujia ,&nbsp;Venkatesh Vempati ,&nbsp;M. Ravi Kumar","doi":"10.1016/j.pepi.2025.107364","DOIUrl":"10.1016/j.pepi.2025.107364","url":null,"abstract":"<div><div>This study attempts to understand the upper mantle deformation patterns beneath the Eastern Himalaya by performing shear wave splitting analysis of core-refracted phases. Out of the 83 broadband seismic stations used, data from 70 stations are analysed for the first time. This includes 21 stations which were newly deployed along two profiles in Arunachal Himalaya, to fill the gaps in the stations used for previous studies. In total, 172 well constrained new splitting and 215 null measurements are obtained in this study. Average delay time values of 0.64 and 0.76 s in the Bhutan and Arunachal Himalaya respectively, suggest weak anisotropy, probably due to a steep subduction of the Indian mantle lithosphere. There is a systematic variation in the orientation of fast polarization azimuths in the western (Bhutan Himalaya and western part of Arunachal Himalaya) and eastern segments (central to the eastern part of Arunachal Himalaya). In both these segments, the orientation of fast polarization azimuths varies dominantly from N<em>E</em>-SW or/and ENE-WSW, to E-W, from west to east. In the western and central parts of Bhutan Himalaya, the influence of absolute plate motion related strain in the asthenospheric mantle cannot be ruled out, while in its eastern part and Arunachal Himalaya, the azimuthal anisotropy can be explained by arc parallel mantle flow due to slab rollback. In addition, a few observations in the central part of Arunachal Himalaya indicate a slightly larger delay time, along NNE-SSW, which could be associated with mantle wedge flow. The eastern part of Arunachal Himalaya might be associated with a repulsive arc parallel flow from the Arunachal and Burmese arcs, resulting in null measurements. The optimal depth of anisotropy in Bhutan and Arunachal Himalaya is around <span><math><mn>220</mn><mo>−</mo><mn>270</mn></math></span> and <span><math><mn>200</mn><mo>−</mo><mn>240</mn></math></span> km respectively, suggesting that the source of anisotropy lies in the upper part of the asthenosphere.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107364"},"PeriodicalIF":2.4,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial variation of crustal anisotropy in Simeulue Island, Indonesia, from shear wave splitting analysis","authors":"Syuhada Syuhada ,&nbsp;Faiz Muttaqy ,&nbsp;Titi Anggono ,&nbsp;Bayu Pranata ,&nbsp;Nanang T. Puspito ,&nbsp;Mohamad Ramdhan ,&nbsp;Febty Febriani ,&nbsp;Muhammad Ma'ruf Mukti ,&nbsp;Cinantya Nirmala Dewi ,&nbsp;Mohammad Hasib ,&nbsp;Aditya Dwi Prasetio ,&nbsp;Atin Nur Aulia ,&nbsp;Ade Surya Putra","doi":"10.1016/j.pepi.2025.107362","DOIUrl":"10.1016/j.pepi.2025.107362","url":null,"abstract":"<div><div>Simeulue Island sits near the northern subduction margin of the Sumatran Megathrust, which is characterized by high tectonic activities and earthquakes. The oblique subduction along this margin has developed a complicated crustal deformation on the island, including faulting, uplifting and crustal segmentation. In the subduction zone, crustal anisotropy is often caused by stress-induced anisotropy in which the anisotropy direction is parallel to the stress direction. However, the complex crustal structure around the study area may produce a complicated anisotropy pattern. Here, we measure crustal seismic anisotropy from shear wave splitting analysis using the seismic data recorded at eight temporary stations spread across Simeulue Island. We apply the 2-D tomographic inversion and spatial averaging technique to map the splitting anisotropy patterns around the region. This research allows us to gain new insight into the crustal deformation pattern and its relationship with the complicated crustal structure beneath the island. The splitting result shows variations of anisotropy pattern around the study area. The spatially averaged fast directions at the northern region are trench-parallel, consistent with the strike of the geological features resulting from the strain partitioning deformation of the oblique convergence. Higher strength anisotropy is also observed in this area, indicating that the local fault system may strongly contribute to the crustal anisotropy. In the southern part of the island, the spatial averaging of fast direction gives a consistent pattern with the maximum regional stress direction, suggesting that anisotropy is mainly associated with stress-aligned microcracks. The central part of the island exhibits different splitting directions, marking the boundary of the geological structures between the areas in the north and south of the island. This pattern is also accompanied by high-strength anisotropy, suggesting that the source may be associated with the subducting geological structures beneath the area playing a significant role in the rupture barrier of the great events, as suggested by several previous studies.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107362"},"PeriodicalIF":2.4,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The history of geomagnetic secular variation hemispherical dichotomies","authors":"Mathis Colas,&nbsp;Filipe Terra-Nova,&nbsp;Hagay Amit","doi":"10.1016/j.pepi.2025.107352","DOIUrl":"10.1016/j.pepi.2025.107352","url":null,"abstract":"<div><div>Monitoring the geomagnetic field and its secular variation (SV) is essential for understanding the Earth's internal dynamics. In particular, the SV provides an image of the geodynamo at the top of the core. However, the SV is not available for paleomagnetic field models. Here, we propose a new index for assessing the paleomagnetic SV. This new index is based on the well-established inverse linear relationship between the SV timescales and the degree of spherical harmonics. We demonstrate using the historical field where the SV is available that this index adequately captures the large-scale features of the true SV, in particular the SV Atlantic/Pacific and North/South dichotomies. The recovery of these SV hemispherical dichotomies by our proposed index does not deteriorate from truncated fields at spherical harmonics degree 14 to 5. Applied to a paleomagnetic field model for the past 100 kyr, we find a persistent SV dichotomy between the quiet Pacific and active Atlantic hemispheres, consistent with heterogeneous inner core freezing. In addition, according to our index, a persistent stronger SV prevails at the northern hemisphere, which is the case at the present day due to a fast westward jet at high latitudes of the northern hemisphere.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107352"},"PeriodicalIF":2.4,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143844796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrical and thermal conductivities of Fe–Ni–Si alloy under core conditions: A reevaluation","authors":"Kenji Ohta ,&nbsp;Hayato Inoue ,&nbsp;Sho Suehiro ,&nbsp;Kei Hirose ,&nbsp;Saori Kawaguchi-Imada ,&nbsp;Haruhiko Dekura","doi":"10.1016/j.pepi.2025.107351","DOIUrl":"10.1016/j.pepi.2025.107351","url":null,"abstract":"<div><div>We present experimental results on the electrical resistivity (the inverse of electrical conductivity) of solid hexagonal close-packed (hcp) and liquid Fe–10 at.% Ni–22.5 at.% Si (Fe–11.8 wt% Ni–12.7 wt% Si) alloys under high-pressure and high-temperature conditions, corresponding to the Earth's outer core conditions, using a diamond anvil cell. We found minimal temperature dependence of the resistivity of the hcp Fe–Ni–Si alloy, indicating thermochemically-induced resistivity saturation. We also observed that the resistivity saturation reduced the extent of resistivity change during the melting transition. Based on our findings, we estimate an upper limit for the core resistivity of approximately 110 μΩcm (= 1.10 × 10⁻⁶ Ωm) at the top of the outer core, corresponding to a lower limit for the electrical and thermal conductivities of approximately 9.2 × 10⁵ Sm⁻¹ and 90 Wm⁻¹ K⁻¹, respectively. Such high core conductivity is unavoidable and must be accounted for in understanding the Earth's thermal evolution.</div><div><em>“Extrapolation to core conditions of laboratory observations of electrical resistivities of iron and its alloys has been hampered by lack of understanding of interactions between the effects of temperature, pressure and impurities.”—F. D. Stacey and O.</em> L. <em>Anderson (2001).</em></div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107351"},"PeriodicalIF":2.4,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithospheric structure beneath the Upper Indus Basin and its adjacent regions from inversion of surface wave dispersion","authors":"Deepak Kumar ,&nbsp;G. Suresh ,&nbsp;M.L. Sharma ,&nbsp;Siddharth Dey ,&nbsp;S.C. Gupta","doi":"10.1016/j.pepi.2025.107345","DOIUrl":"10.1016/j.pepi.2025.107345","url":null,"abstract":"<div><div>We propose an enhanced model of the crust and upper mantle structure beneath the Upper Indus Basin, derived from the combined inversion of Rayleigh and Love wave group velocity dispersion data from 164 seismic events recorded by 58 stations, covering periods from 4 to 100 s. By using the Genetic Algorithm approach within this joint inversion process, we developed a detailed shear wave velocity model for the region. The earthquakes were categorized into three clusters based on their epicentral locations, allowing for a detailed analysis beneath the western, central, and eastern segments of the Upper Indus Basin. The analysis shows a gradual increase in crustal thickness from the west to the east, with an average thickness of ∼61.8 km and a shear wave velocity ∼ 4.6 km/s. The Lithosphere-Asthenosphere Boundary (LAB) is identified at a depth of 160 km, indicated by a velocity decrease of about 1.6 %. Our results also reveal a sedimentary cover of ∼4 km and we postulate a felsic crust similar to southern Pamir, which could have resulted from the loss of mafic lower crust by lithospheric delamination or foundering due to gravitational instability. We state the absence of mid-crustal low velocity layer within the Basin and also discard the possibility of any requirement for radial anisotropy, based on the adequate fit of Rayleigh and Love the dispersion data with minimal uncertainty. The study provides a significant refinement of the crustal and upper mantle structure of the Upper Indus Basin, contributing valuable insights into regional tectonics.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"362 ","pages":"Article 107345"},"PeriodicalIF":2.4,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shared periodicities between the length of day and the geomagnetic field at millennial timescales","authors":"M. Puente-Borque ,&nbsp;F.J. Pavón-Carrasco ,&nbsp;S.A. Campuzano ,&nbsp;A. González-López ,&nbsp;M. Folgueira ,&nbsp;M.L. Osete","doi":"10.1016/j.pepi.2025.107350","DOIUrl":"10.1016/j.pepi.2025.107350","url":null,"abstract":"<div><div>The dynamics of Earth's outer core control the geomagnetic field and produce variations in the length of day (LOD). This phenomenon has been extensively studied at decadal and interannual scales but is still little known on the millennial timescale. Reconstructed variations in the length of day from ancient records of eclipses exhibit an oscillating component with a millennial period that cannot be explained by tidal effects, glacial isostatic adjustment or the ocean and atmospheric dynamics. In this work, frequency analysis and correlation techniques have been applied to LOD variations and to the dipole and quadrupole geomagnetic field provided by paleomagnetic reconstructions. We found that the non-tidal fluctuations of the LOD are correlated with the paleosecular variation of the Earth's magnetic field over the last three millennia. In particular, LOD maxima occur when the eccentric dipole shifts towards the Pacific region and the geocentric dipole becomes more axial, and LOD minima correspond to a more centred eccentric dipole and a more tilted geocentric dipole towards Atlantic region. These results provide new information about the coupling between the Earth's rotation and the paleosecular variation of the geomagnetic field on millennial time scales.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"362 ","pages":"Article 107350"},"PeriodicalIF":2.4,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the thermal evolution and magnetic field generation of planet Mercury","authors":"Jurrien Sebastiaan Knibbe ,&nbsp;Attilio Rivoldini ,&nbsp;Yue Zhao ,&nbsp;Tim Van Hoolst","doi":"10.1016/j.pepi.2025.107348","DOIUrl":"10.1016/j.pepi.2025.107348","url":null,"abstract":"<div><div>Heat transfer through convection in Mercury's large core may be limited to a liquid layer between a solid inner core and a stably stratified outer liquid layer. Convection in the thin mantle may even have entirely stopped. Here, we consider the transition from convective to conductive heat transport in a coupled thermal evolution model of the mantle and core and assess implications for the generation of the magnetic field.</div><div>We argue that a conductive temperature profile best describes the temperature in regions of the core with a subadiabatic heat flux. Implementing an adiabat in these regions in a model of the evolution of the core, as is often done, implicitly assumes the existence of a mechanism that transports heat downward. Such a mechanism not only consumes power that could otherwise be available for sustaining dynamo action, but is also unlikely to be effective.</div><div>We show that a thermally convective layer deep in Mercury's liquid core below a thermally stratified layer is more likely to persist until present if light elements depress the liquidus of the core by several hundred degree compared to iron. Substantial partitioning of light elements into the liquid core can drive strong compositional convection in the upper part of Mercury's core, but this may not be in line with dynamo studies that are consistent with the observed magnetic field. Therefore, thermal evolution scenarios with light elements in the core that depress the core liquidus significantly but do not strongly fractionate into the core liquid are the most consistent with the present-day core dynamo.</div><div>Present-day dynamo action below a thermally stratified layer does not necessarily imply that the mantle is currently convective. If the mantle has a high concentration of radiogenic elements and a low viscosity, it must be convecting, but mantle convection can have ended before the present for a more viscous mantle with low concentration of radiogenic elements.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"363 ","pages":"Article 107348"},"PeriodicalIF":2.4,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Joint interpretation of potential field data using independent Lpq norm inversion and geological modeling: Application to Iron targeting in Central Iran","authors":"Bardiya Sadraeifar ,&nbsp;Reza Ghanati ,&nbsp;Mohammad Hakim Rezayee ,&nbsp;Maysam Abedi ,&nbsp;Seyed Hossein Hosseini ,&nbsp;Vahid E. Ardestani","doi":"10.1016/j.pepi.2025.107347","DOIUrl":"10.1016/j.pepi.2025.107347","url":null,"abstract":"<div><div>Solving applied geophysical inverse problems using the <span><math><msub><mi>L</mi><mi>pq</mi></msub></math></span> norm (mixed <span><math><msub><mi>L</mi><mi>p</mi></msub></math></span>norm) is a well-established deterministic method, particularly in potential-field inversions. This approach minimizes the objective function by integrating <span><math><msub><mi>L</mi><mi>p</mi></msub></math></span> norms (<span><math><mn>0</mn><mo>≤</mo><mi>p</mi><mo>≤</mo><mn>2</mn></math></span>) for the smallness and smoothness terms in the regularization function, offering high flexibility in controlling the sparsity and smoothness of the recovered models. This study focuses on the computational aspects and parameters of the model structure term that significantly influence the generation of density and susceptibility models. We investigate how different combinations of <span><math><msub><mi>L</mi><mi>p</mi></msub></math></span> norms and scaling constants for the smallness and smoothness terms affect the recovery of various geometrical structures and the delineation of iron ore resources. The initial phase of our study involves testing these parameters using a synthetic model designed for gravity and magnetic susceptibility inversion, incorporating a complex dataset. Subsequently, we apply mixed <span><math><msub><mi>L</mi><mi>p</mi></msub></math></span> norm inversion with different norm combinations to ground-based potential field data from an iron ore deposit in the Bafq metallogenic belt, central Iran. This region is characterized by a reverse fault that has induced a north-south trend in hematite-magnetite mineralization. A key focus of this study is the impact of employing identical versus non-identical norms in the smoothness term of the model structure. By adjusting the level of compactness to match the target trend, we generate a geologically more interpretable model. Following the inversion, we assess the effectiveness of various combinations of <span><math><msub><mi>L</mi><mi>p</mi></msub></math></span> norm in delineating mineralized zones by comparing the inverted models to a lithological model obtained via co-kriging interpolation of borehole data. The results reveal significant hematite mineralization, with high-grade deposits predominantly located in the hanging wall of the fault and lower-grade deposits in the footwall. The magnetite mineralization, while less extensive, exhibits a spatial distribution similar to that of hematite, though it is typically shallower in comparison.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"362 ","pages":"Article 107347"},"PeriodicalIF":2.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strong compositional gradient in the Earth's inner core?","authors":"Hitoshi Gomi ,&nbsp;Kei Hirose","doi":"10.1016/j.pepi.2025.107349","DOIUrl":"10.1016/j.pepi.2025.107349","url":null,"abstract":"<div><div>Dynamic motions in the Earth's solid inner core driven by thermo-chemical buoyancy, such as plume convection and translation, have been proposed to explain seismic observations. The inner core should be chemically homogeneous if it is actively agitated. However, its high thermal conductivity may suppress such motions. Here we computed the equations of state for six hundred and ninety-three different Fe-Ni-Si-S-H alloys and compared their density (<em>ρ</em>) and bulk sound velocity (<em>V</em>_Φ) profiles with inner core seismic reference models. While such calculations were made at static conditions, we additionally calculated the Helmholtz energy by using the quasi-harmonic approximation to obtain the <em>ρ</em> and <em>V</em>_Φ of hexagonal close-packed (hcp) alloys under high temperatures relevant to the inner core. The results demonstrate that the changes in <em>ρ</em> of these hcp alloys along the inner core <em>P-T</em> profile are comparable to the radial <em>ρ</em> gradients shown by the PREM and AK135 models, but none of the Fe-Ni-Si-S-H alloys explain the gentle gradients in <em>V</em>_Φ of these reference models. Given that the PREM and AK135 models provide the correct <em>V</em>_Φ gradient, it suggests compositional stratification in the solid inner core, much stronger than can be developed upon crystallization from a homogeneous liquid outer core. The inner core might have crystallized from a chemically stratified liquid core (S-poor and H-rich toward the centre), which possibly formed as a result of liquid immiscibility between S-rich and H-rich liquids.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"362 ","pages":"Article 107349"},"PeriodicalIF":2.4,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}