Earth and Planetary Science Letters最新文献

{"title":"Spatial biases in oxygen-based Phanerozoic seawater temperature reconstructions","authors":"Alexandre POHL ,&nbsp;Thomas W. WONG  HEARING ,&nbsp;Arnaud BRAYARD ,&nbsp;Ethan GROSSMAN ,&nbsp;Michael M. JOACHIMSKI ,&nbsp;Guillaume LE  HIR ,&nbsp;Thomas LETULLE ,&nbsp;Daniel J. LUNT ,&nbsp;Mathieu MARTINEZ ,&nbsp;Emmanuelle PUCEAT ,&nbsp;Guillaume SUAN ,&nbsp;Paul VALDES ,&nbsp;Yannick DONNADIEU","doi":"10.1016/j.epsl.2025.119418","DOIUrl":"10.1016/j.epsl.2025.119418","url":null,"abstract":"<div><div>Stable oxygen isotopes (δ¹⁸O) are routinely used to reconstruct sea-surface temperatures (SSTs) in the geological past, with mineral δ¹⁸O values reflecting a combination of the temperature and oxygen isotope composition of seawater (δ¹⁸O_sw). Temporal variation of mean-ocean δ¹⁸O_sw is usually accounted for following estimates of land-ice volume. Spatial variations in δ¹⁸O_sw, however, are often neglected or corrected using calibrations derived from the present-day or recent past. Geochemical methods for constraining δ¹⁸O_sw and isotope-enabled general circulation model (GCM) simulations are still technically challenging. This lack of constraints on ancient δ¹⁸O_sw is a substantial source of uncertainty for SST reconstructions. Here we use the co-variation of δ¹⁸O_sw and seawater salinity, together with GCM simulations of ocean salinity, to propose estimations of spatial variability in δ¹⁸O_sw over the Phanerozoic. Sensitivity tests of the δ¹⁸O_sw-salinity relationship and climate model, and comparison with results of isotope-enabled GCMs, suggest that our calculations are robust at first order. We show that continental configuration exerts a primary control on δ¹⁸O_sw spatial variability. Complex ocean basin geometries in periods younger than 66 Ma lead to strong inter-basinal contrasts in δ¹⁸O_sw. Latitudinal SST gradients may be steeper than previously suggested during most of the Mesozoic and Cenozoic. This work has limitations, with δ¹⁸O_sw-salinity relationships being less reliable in both low-latitude epicontinental settings and high-latitude regions of deep-water formation. Whilst our calculations are limited use in correcting δ¹⁸O measurements for local δ¹⁸O_sw, they identify the time slices and paleogeographical regions that should be prioritized for future work using isotope-enabled GCMs.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"663 ","pages":"Article 119418"},"PeriodicalIF":4.8,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143922245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unexpected megathrust slip evolution revealed by the 2024 Mw 7.1 and the 2025 Mw 6.8 Hyuga-nada earthquakes in southwest Japan","authors":"Xiaolong Zhang ,&nbsp;Shaoyang Li ,&nbsp;Ling Chen","doi":"10.1016/j.epsl.2025.119384","DOIUrl":"10.1016/j.epsl.2025.119384","url":null,"abstract":"<div><div>Subduction faults were thought to slip either seismically as earthquakes or aseismically through creep, representing two end-member frictional behaviors. A dynamic transition from interseismic creep to coseismic failure during rupture had also been proposed. However, the potential for a subduction fault segment to transition between seismic and aseismic mode in a time scale of days to months remains poorly understood, constrained by the remote offshore nature of these zones and limited instrumentation in most subduction regions. Here, we investigate the coseismic and time-dependent postseismic slip associated with the 2024 and 2025 megathrust events in Hyuga-nada, Japan, using dense inland GNSS data, aftershocks and a finite-element model. Our preferred source model of the 2024 event identifies a quasi-circular, thrust-dominated rupture with a geodetic moment magnitude (Mw) of 7.1 and a maximum slip of ∼1.5 m. This event occurred at relatively greater depths (15–30 km), compared to previous M7 events in the region, along the downdip edge of the inferred subducting Kyushu-Palau Ridge. Kinematic analysis of postseismic displacements indicates that the initial 50 days of afterslip were excited concurrently with ample plate-interface aftershocks in the earthquake source region and migrated downdip to the northwest into an area previously characterized by long-term and short-term slow slip events. These overlaps between coseismic and postseismic slip, as well as between postseismic slip and slow slip events, align with earlier observations from the 1996 doublet events in the vicinity of the 2024 rupture, albeit with less dense data. Approximately one month after the mainshock, an additional aseismic slip episode initiated at depths of 60–80 km, coinciding with a burst of M0–2 aftershocks in the same region. Approximately five months later, an Mw 6.8 event occurred within the main afterslip area of the 2024 event, forming a doublet with the 2024 event and largely overlapping with the rupture zone of the December 1996 event. Our findings highlight the complex, depth-dependent interplay between subducting geometrical irregularities and local megathrust rheology, which governs the partitioning of seismic and aseismic slip to accommodate the oceanic plate subduction. This interplay also appears to allow the subduction fault to transition mechanically between fast and slow slip modes on a large scale and over an unexpectedly short timescale. The unexpected dynamic slip behavior underscores the need for a systematic, global reassessment of the effects of subducting topography on megathrust slip behavior and earthquake hazards.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119384"},"PeriodicalIF":4.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drainage divide formation by uplift gradient onset: The case of the southern sector of the Main Gulf Escarpment, Baja California Peninsula, Mexico","authors":"Arturo Godínez–Tamay,&nbsp;Miguel Castillo,&nbsp;Esperanza Muñoz–Salinas","doi":"10.1016/j.epsl.2025.119411","DOIUrl":"10.1016/j.epsl.2025.119411","url":null,"abstract":"<div><div>Field cases and numerical simulations support that uplift gradients set drainage divide close to the high uplift side. However, the development of a mountain landscape since the onset of one uplift gradient has been poorly documented. We analyze the case of the Main Gulf Escarpment (MGE) on the Baja California Peninsula (Western Mexico). The MGE is a landscape feature produced by El Carrizal Fault (ECF), an active normal fault that runs obliquely to the rifting system of the Gulf of California. By analyzing the rivers of the southern sector of the MGE with different approaches such as linear inversion, <em>k</em>_sn index, and drainage divide positions, we document how the different episodes along ECF tilted a volcanoclastic rock sequence known as Comondú Group, forming a main drainage divide that now corresponds to the MGE. The fault activity, which began in the Late–Miocene, was also advantageous in providing a reference time span to constrict the incision response of rivers to the episodes along ECF.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119411"},"PeriodicalIF":4.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What is the present-day tectonic uplift rate of the Tibetan Plateau?","authors":"Weilong Rao ,&nbsp;Bin Liu ,&nbsp;Tengfei Feng ,&nbsp;Qiuyu Wang ,&nbsp;He Tang","doi":"10.1016/j.epsl.2025.119389","DOIUrl":"10.1016/j.epsl.2025.119389","url":null,"abstract":"<div><div>The Tibetan Plateau (TP) exhibits millimeter-scale vertical crustal deformation, detected through Global Positioning System (GPS) measurements. Concurrently, significant terrestrial water loss in High Mountain Asia contributes to plateau uplift via hydrological loading. After accounting for loading-induced uplift, it remains unclear whether the TP continues to experience significant tectonic uplift. To resolve this, a global hydrological mass change field was reconstructed using satellite observations and hydrological models, rather than relying on the Gravity Recovery and Climate Experiment (GRACE) data, to quantify vertical loading displacement rates for correcting GPS vertical velocities. Furthermore, a GPS imaging technique that incorporates the spatial structure function (SSF) was used to generate a tectonic deformation image of the TP. The results indicate that the TP is not experiencing uniform and significant tectonic uplift; instead, regional crustal subsidence is observed. The mean tectonic uplift rate is only 0.31 ± 0.32 mm/yr, which is smaller than the 0.46 ± 0.08 mm/yr contributed by loading and glacial isostatic adjustment (GIA).</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119389"},"PeriodicalIF":4.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143922790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Behaviour of cadmium isotopes in sulfidic waters and sediments of the Black Sea: Implications for global cadmium cycling and the application of cadmium isotopes as a paleo-oceanographic proxy","authors":"Alexander J. Dickson ,&nbsp;Allison L. Bryan ,&nbsp;Ejin George ,&nbsp;Gideon M. Henderson ,&nbsp;Donald Porcelli ,&nbsp;John Rolison ,&nbsp;Caroline P. Slomp ,&nbsp;Rob Middag ,&nbsp;Claudine H. Stirling","doi":"10.1016/j.epsl.2025.119408","DOIUrl":"10.1016/j.epsl.2025.119408","url":null,"abstract":"<div><div>The cadmium isotope system has found use as a tracer for biological productivity, redox and organic carbon burial in the oceans. There are, however, very few observational constraints on Cd isotopic behaviour in modern sulfidic marine conditions, limiting our understanding of the modern Cd cycle, and our ability to use Cd isotope measurements of ancient sedimentary deposits as a paleoceanographic proxy. Here we study the behaviour of dissolved Cd in the water column of the Black Sea and its incorporation into sediments on the basin floor. The isotopic composition of dissolved Cd in the upper ∼50 m of the Black Sea water column is controlled by a combination of biological uptake and regeneration along with mixing of river water and Mediterranean seawater. Cadmium declines to &lt;2 % of its peak subsurface concentration within the zone of nitrate-reduction but above the sulfide chemocline. The isotopic composition of dissolved Cd below the sulfide chemocline evolves in a manner that is consistent with experimental Cd sulfide fractionation factors, providing field-based support for these earlier studies. In contrast, the stability of the dissolved Cd isotopic signature above the chemocline, despite a large reduction in dissolved Cd concentrations, is explained by diffusion towards the Cd-sulfide sink below the chemocline. Sediments accumulating in the deep Black Sea below the sulfide chemocline have isotopic compositions that are similar to dissolved Cd in its near-surface aqueous concentration maximum. Sediments accumulating at shallower depths have lighter isotopic compositions that are likely affected by non-sulfidic burial pathways mediated by macrofaunal mixing and diagenesis of shallow burial phases. Our study shows that the isotopic composition of bulk sediments accumulating under sulfidic conditions is similar to dissolved Cd in the upper water column, supporting its use as a paleo-chemical proxy for ancient seawater as long as basin-scale controls on open ocean seawater sources are considered. We show that Cd burial in the deep Black Sea, predominantly as CdS, accounts for ∼0.5–15 % of total annual Cd burial in the global ocean.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119408"},"PeriodicalIF":4.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling remagnetization sources using statistical learning","authors":"L.C. Gallo ,&nbsp;M. Domeier ,&nbsp;P.Y. Antonio ,&nbsp;F. Sapienza ,&nbsp;A. Rapalini ,&nbsp;E. Font ,&nbsp;T. Adatte ,&nbsp;R.I.F. Trindade ,&nbsp;F. Temporim ,&nbsp;J. Tonti-Filippini ,&nbsp;P. Silkoset ,&nbsp;L. Warren","doi":"10.1016/j.epsl.2025.119390","DOIUrl":"10.1016/j.epsl.2025.119390","url":null,"abstract":"<div><div>The paleomagnetic archive provides invaluable insights into Earth's history, but its records are often obscured by various geological processes. A prime example is remagnetization, which can replace the original natural remanent magnetization. Although magnetic overprints can be detected by traditional paleomagnetic tests, the mechanisms responsible for them often remain elusive because linking bulk magnetic properties to their microscopic sources is inherently challenging. Here, we bridge this gap by pairing an extensive rock magnetic and geochemical dataset with statistical learning techniques for the first time. Using a Random Forest regressor trained on geochemical data, we accurately predict the growth of fine-grained magnetite in an undeformed late Ediacaran section of remagnetized carbonate rocks from Paraguay. Our modeling results identify the K/Al ratio—alongside K and Sr contents—as key predictors of this remagnetization mechanism. Notably, clay mineralogy analyses further link the K/Al ratio to enhanced clay authigenesis (illitization) driven by K-feldspar dissolution and albitization—processes that also release iron. Together, these findings indicate that remagnetization occurred via authigenic magnetite formation under isochemical diagenesis—without the involvement of external fluids. This novel application of statistical learning to uncover the geochemical drivers of chemical remagnetizations provides a robust framework to investigate and understand these events. It could also open new avenues for their direct dating, thereby significantly enriching the global paleomagnetic record.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119390"},"PeriodicalIF":4.8,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnesian-suite volcanism and ancient crust building on the Moon 4.25 billion years ago","authors":"Christopher Yen ,&nbsp;Cécile Deligny ,&nbsp;Bradley Jolliff ,&nbsp;Alexander Nemchin ,&nbsp;Paul Carpenter ,&nbsp;Martin Whitehouse ,&nbsp;Renaud Merle ,&nbsp;Ryan Ogliore ,&nbsp;Jeremy Kent ,&nbsp;Ryan Zeigler ,&nbsp;Juliane Gross ,&nbsp;Scott Eckley ,&nbsp;Steven Simon ,&nbsp;Charles Shearer ,&nbsp;the ANGSA Science Team","doi":"10.1016/j.epsl.2025.119395","DOIUrl":"10.1016/j.epsl.2025.119395","url":null,"abstract":"<div><div>We present a 4.25-billion-year-old volcanic rock petrogenetically linked to the Mg suite, together with a related glass bead from the same Apollo 17 core 73002, which was unsealed as part of NASA’s ANGSA program. This basalt, with porphyritic texture and magnesian-suite composition, has a crystallization age of 4246 ± 4 million years. Phase equilibrium modeling indicates that this picritic basalt is related to glass in 73002 and formed when a mantle melt interacted with anorthositic crust before eruption. The presence of extrusive, olivine-rich Mg-suite samples indicates that high-temperature lunar magmas had sufficient energy or buoyancy to breach the early crust. Subsequent events, namely the late heavy bombardment and mare volcanism, possibly obscured evidence of ancient volcanism, or the early Moon was dominated by intrusive rather than extrusive magmatism. These findings also offer insight into magmatic processes on early Earth before the onset of plate tectonics, where such samples have been destroyed by geologic processes and where most ancient igneous ages have come from individual zircon grains rather than whole rocks. Our results support a dynamically evolving early Moon, expanding our understanding of primordial crust formation and thermal evolution on early Earth and other rocky planets.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119395"},"PeriodicalIF":4.8,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluid pressure fluctuations and the seismic signature of a fault-controlled fluid migration pulse","authors":"Ashley Stanton-Yonge ,&nbsp;Almudena Sánchez De La Muela ,&nbsp;Rebecca K. Pearce ,&nbsp;James O.S. Hammond ,&nbsp;Thomas M. Mitchell ,&nbsp;Stephen P. Hicks ,&nbsp;W. Ashley Griffith ,&nbsp;Max Moorkamp ,&nbsp;Philip G. Meredith ,&nbsp;José Cembrano","doi":"10.1016/j.epsl.2025.119388","DOIUrl":"10.1016/j.epsl.2025.119388","url":null,"abstract":"<div><div>Fluids in the crust may build pressure through a variety of mechanisms. This buildup can activate nearby faults, which then serve as conduits for fluid flow and as valves for pressure release. The rapid pressure drop promotes mineral precipitation and fault sealing, allowing the cycle to restart. While evidence of this cyclical interplay between faults and fluids is abundant in exhumed faults, whether these processes can be identified in the seismological record remains unknown. Here, we have detected a complete sequence of fluid pressure build-up, fluid migration through local faults, and pressure release by means of a joint magnetotelluric and seismicity survey in the Southern Andes. We identified intense seismicity along a previously unmapped WNW-striking fault, with seismic swarm activity concentrated at the edge of a low-resistivity crustal zone, interpreted as a fluid reservoir. Hypocenters delineate two fault planes from the reservoir toward higher-resistivity crust. We linked distinct seismicity patterns to each sequence stage: fluid pressure buildup is marked by relatively high <em>b</em>-values (1.2–1.4) and low magnitudes (<span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>&lt;</mo><mn>1.5</mn></math></span>), while fluid migration and pressure release are characterized by a sudden drop in <em>b</em>-values (&lt;1). Our findings capture the seismic signature of a fluid migration pulse along faults, linking active fault-fluid interactions with long-term geological evidence of fluid compartmentalization and cyclical along-fault fluid flow.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119388"},"PeriodicalIF":4.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of eclogitic clasts in CR chondrite Northwest Africa 801: Growing evidence for large parent bodies in the CR reservoir of the early solar system","authors":"J.S. Gorce ,&nbsp;E.A. Heiny ,&nbsp;J. Filiberto ,&nbsp;C. Goodrich","doi":"10.1016/j.epsl.2025.119371","DOIUrl":"10.1016/j.epsl.2025.119371","url":null,"abstract":"<div><div>There is a growing body of evidence that the range of planetary parent bodies sizes is greater than previously understood as new pressure and temperature <em>(P-T)</em> estimates of amphibolite and eclogite mineral assemblages found in chondrites are determined and subsequently used to estimate parent body sizes. Here we use thermodynamic modelling techniques to estimate that clasts containing eclogite-like minerals found in NWA 801 equilibrated at 13-15 kbars and 720°C under dry metamorphic conditions, and hydrous phases form after peak metamorphism during aqueous alteration at P∼4-6 kbars and T ∼ 200-400°C and a water/rock ratio of ∼0.006 (&lt; 0.5 wt % H₂O). Parent body size estimates are similar to previous work (2050-3700 km), but do not require that the eclogitic clasts be sampled from near the center of the parent body to achieve a peak metamorphic pressure of 13-15 kbars. The eclogitic clasts in NWA 801 are part of a growing body of evidence that imply that chondritic parent bodies could have been much larger than what has been suggested in the past (1000s vs 10s-100s km in diameter), and that the diversity of size in chondritic parent bodies is much greater than previously understood.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119371"},"PeriodicalIF":4.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How increased intrinsic viscosity of lower mantle compositional reservoirs affects their spatial and morphological stability","authors":"Jiaxin Zhang ,&nbsp;Allen K. McNamara","doi":"10.1016/j.epsl.2025.119393","DOIUrl":"10.1016/j.epsl.2025.119393","url":null,"abstract":"<div><div>The mobility of two Large Low Shear Velocity Provinces (LLSVPs), often hypothesized to be thermochemical piles with higher density in the Earth’s lowermost mantle, is important for paleogeographic reconstructions and understanding the Earth’s mantle dynamics. Recent paleomagnetic studies have implied that the LLSVPs may remain stationary over geological time, while Flament et al. (2022) showed the paleomagnetic data could also be explained by mobile LLSVPs. Traditional thermochemical models employing the same rheological formulation for piles and the background mantle consistently show mobile piles easily deformed by changing subduction patterns; however, piles may have a higher intrinsic viscosity due to a larger grain size or other compositional differences. Here, we investigate whether and how composition-dependent rheology can explain the possible lateral fixity of thermochemical piles. We performed effectively 2D geodynamical calculations in a spherical annulus geometry to investigate how thermochemical piles with increased intrinsic viscosity respond to slabs and plumes. As pile viscosity increases, we find that the pile morphology is more stable against changing upwelling flow. However, piles remain laterally mobile even when their viscosity is 5000 times higher than the ambient mantle. In summary, we find that increased thermochemical pile viscosity stabilizes pile morphology yet does not make them less laterally mobile. If LLSVPs are laterally fixed, another mechanism must be found.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"662 ","pages":"Article 119393"},"PeriodicalIF":4.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}