Journal of Geophysical Research: Planets最新文献

{"title":"Amapari Marker Band Metal-Enrichments: Potential Mechanisms and Implications for Surface and Subsurface Water and Weathering in Gale Crater","authors":"P. J. Gasda,&nbsp;E. S. Kite,&nbsp;L. M. Thompson,&nbsp;C. Mondro,&nbsp;W. E. Dietrich,&nbsp;C. M. Weitz,&nbsp;B. Tutolo,&nbsp;W. H. Farrand,&nbsp;E. Hausrath,&nbsp;A. Cowart,&nbsp;N. L. Lanza,&nbsp;K. W. Lewis,&nbsp;S. Gupta,&nbsp;A. Roberts,&nbsp;W. Goetz,&nbsp;H. E. Newsom,&nbsp;L. Crossey,&nbsp;J. Lightholder,&nbsp;C. Hardgrove,&nbsp;J. Schieber,&nbsp;S. P. Schwenzer,&nbsp;S. J. VanBommel,&nbsp;S. Schröder,&nbsp;C. D. O'Connell-Cooper,&nbsp;D. Das,&nbsp;D. Rubin,&nbsp;W. Rapin,&nbsp;T. F. Bristow,&nbsp;E. Rampe,&nbsp;P. D. Archer Jr,&nbsp;C. Seeger,&nbsp;G. Caravaca,&nbsp;J. R. Johnson,&nbsp;S. Le Mouélic,&nbsp;J. A. Grant,&nbsp;J. Davis,&nbsp;J. Lasue,&nbsp;A. Yingst,&nbsp;A. B. Bryk,&nbsp;M. P. Lamb,&nbsp;W. W. Fischer,&nbsp;C. House,&nbsp;E. Dehouck,&nbsp;A. Essunfeld,&nbsp;R. Milliken,&nbsp;R. Sheppard,&nbsp;M. Minitti,&nbsp;D. Ming,&nbsp;S. Simpson,&nbsp;J. Frydenvang,&nbsp;R. M. E. Williams,&nbsp;R. Arvidson,&nbsp;R. Gellert,&nbsp;O. Gasnault,&nbsp;S. M. Clegg,&nbsp;D. Delapp,&nbsp;A. R. Vasavada,&nbsp;A. Fraeman","doi":"10.1029/2025JE009153","DOIUrl":"https://doi.org/10.1029/2025JE009153","url":null,"abstract":"<p>NASA's <i>Curiosity</i> rover is exploring a 5 km tall sedimentary mound that is hypothesized to record the transition from a warm and wet (phyllosilicate-rich) to a cold and drier (sulfate-rich) Mars. Evidence of magnesium sulfate-bearing rock has shown that <i>Curiosity</i> has crossed through this phyllosilicate-sulfate transition. Recently, <i>Curiosity</i> arrived at the Amapari Marker Band, a darker, indurated unit that can be traced laterally for tens of kilometers in orbiter images. Here, <i>Curiosity</i> found evidence for a very broad lake, and bedforms interpreted as wave-ripple laminated sedimentary rock that likely was deposited in shallow water in the explored location, before becoming a deeper lake. These rocks are enriched in Fe, Mn, and Zn which has major implications for groundwater paleohydrology in Gale crater. Three formation hypotheses are considered: concretion formation during early diagenetic alteration of shallow lake sediments, laterization or leaching of the sediments, and addition of Fe, Mn, and Zn by a mildly acidic and reducing groundwater interacting with a redox and/or pH front in a stratified lake. The preferred interpretation of the metal enrichments within the Amapari Marker band sedimentary rocks is that they formed in a shallow water environment at a redox and/or pH front within the ripple unit, which drove precipitation and concentration of metals. If the enrichments are due to groundwater alteration, these processes could link subsurface and surface environments. Water and the presence of high amounts of redox sensitive elements and other metals are favorable indicators for habitability.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009153","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683706","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":"Strong Variability of the Modeled Venus NO Nightglow","authors":"N. Streel,&nbsp;F. Lefèvre,&nbsp;A. Martinez,&nbsp;A. Määttänen,&nbsp;A. Stolzenbach,&nbsp;S. Lebonnois,&nbsp;J. C. Gérard,&nbsp;L. Soret","doi":"10.1029/2025JE009316","DOIUrl":"https://doi.org/10.1029/2025JE009316","url":null,"abstract":"<p>The ultraviolet nightglow of nitric oxide (NO) on Venus offers a unique window into the dynamics and chemistry of its upper atmosphere. We present three-dimensional simulations of Venus' NO nightglow using a ground-to-thermosphere model, revealing a strong, short-timescale variability consistent with observations. The Venus Planetary Climate Model accurately reproduces the altitude of peak emission at 115 km, matching SPICAV data, and shows an average peak brightness of 53 ± 33 kR, only 5% below the observed values. Crucially, the observed variability and morphology of the NO emission are tightly linked to atmospheric dynamics; its maxima strongly correlate with horizontal wind convergence, leading to localized subsidence. This downward transport is essential for delivering nitrogen atoms to fuel the nightglow, making it a critical tracer for understanding Venus's complex atmospheric circulation. Our findings underscore the importance of the NO nightglow as a powerful diagnostic for the solar-to-antisolar circulation on Venus.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009316","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683707","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":"Petrologic Insights Into the South Pole-Aitken Basin From Raman Spectroscopy of Returned Chang'e-6 Coarse Clasts","authors":"Xuejin Lu,&nbsp;Ziyi Jia,&nbsp;Haijun Cao,&nbsp;Jian Chen,&nbsp;Chenyu Cao,&nbsp;Yiheng Liu,&nbsp;Chengxiang Yin,&nbsp;Bowen Su,&nbsp;Yanqing Xin,&nbsp;Le Qiao,&nbsp;Xiaohui Fu,&nbsp;Ying-Bo Lu,&nbsp;Zongcheng Ling","doi":"10.1029/2025JE009620","DOIUrl":"https://doi.org/10.1029/2025JE009620","url":null,"abstract":"<p>As the largest and oldest impact basin on the Moon, the South Pole-Aitken (SPA) basin preserves critical information about the composition and evolution of the deep lunar crust and may even expose materials from the lunar mantle. China's Chang'e-6 mission returned the first farside samples from the southern mare unit of the Apollo basin within the SPA basin, where the regolith records a complex geological history and diverse non-mare lithologies. In this study, Raman spectroscopy was applied to 50 coarse-grained clasts (average diameter of ∼950 μm) from the Chang'e-6 samples to investigate their mineral composition and reveal the lithological diversity of the farside crust within the SPA basin. Based on modal mineralogy, these clasts are classified into breccias (<i>n</i> = 34), basalts (<i>n</i> = 8), and non-mare lithologies (<i>n</i> = 8). The non-mare clasts are dominated by norite (<i>n</i> = 5), anorthosite (<i>n</i> = 2), and troctolite (<i>n</i> = 1), exhibiting Mg# values (molar [Mg/(Mg + Fe)] × 100) of olivine and/or pyroxene ranging from 53 to 73. Notably, noritic clasts provide direct sample-based evidence that the Mg-rich pyroxene annulus of the SPA basin is predominantly composed of ferroan norite, with an average Mg# of ∼64 and model abundances of ∼61 vol% plagioclase and ∼29 vol% orthopyroxene. These results provide new insights into the crustal composition and evolution of the lunar farside within the SPA basin. This study demonstrates the capability of Raman-based lithologic classification and highlights its potential for future in situ mineralogical investigations in forthcoming lunar exploration by Chang'e-7 Lunar Raman Spectrometer.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683661","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":"Thank You to Our 2025 Reviewers and Volunteers","authors":"Amanda R. Hendrix,&nbsp;Debra Buczkowski,&nbsp;Beatriz Sánchez-Cano,&nbsp;Bradley J. Thomson,&nbsp;Jean-Pierre Williams","doi":"10.1029/2026JE009815","DOIUrl":"https://doi.org/10.1029/2026JE009815","url":null,"abstract":"<p>In <i>JGR: Planets</i>, the peer review process is critical to ensuring that the published articles are based on sound scientific principles, follow state-of-the-art techniques while acknowledging relevant prior results, and present exciting discoveries or novel understanding of the fundamental processes that affect solar system objects. <i>JGR: Planets</i> covers a broad range of topics addressing every aspect of geoscience, with the only requirement that the work addresses planetary processes. In 2025, our editorial team included associate editors Adrian Brown, Jun Cui, Razvan Caracas, Leigh Fletcher, Sierra Ferguson, Yang Liu, Ananya Mallik, Angela Marusiak, Germán Martínez, Anna Mittelholz, Molly McCanta, Katarina Miljkovic, Claire Mondro, Naomi Murdoch, Ryan Park, Arianna Piccialli, Laura Schaefer, Mariek Schmidt, Yasuhito Sekine, Kelsi Singer, Michael Sori, Norihiko Sugimoto, Jamey Szalay, David Trang, Zhiyong Xiao and Shaosui Xu, in addition to the authors of this note. We rely on the community's expertise to vet the articles submitted to the journal. In 2025, JGR: Planets benefited from 1,549 reviews provided by 963 volunteer referees. We also received help from 11 guest editors working on 11 active special collections. To these volunteers: We know that you juggle many duties, both professional and personal, and we are truly grateful that you dedicated your time and energy to evaluate manuscripts, suggest improvements, and advise us on their suitability. On behalf of the entire editorial board, we express our heartfelt gratitude to the many scientists who support <i>JGR: Planets</i>. Thank you! You are performing a valued service to this journal and to the community.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2026JE009815","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683670","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":"Investigating the Detectability of Body Wave Phases From Tidal Ice Cracking Events on Titan With the Dragonfly Short-Period Seismometer","authors":"L. Delaroque,&nbsp;T. Kawamura,&nbsp;A. Lucas,&nbsp;S. Rodriguez,&nbsp;K. Onodera,&nbsp;H. Shiraishi,&nbsp;R. Yamada,&nbsp;S. Tanaka,&nbsp;M. P. Panning,&nbsp;R. D. Lorenz","doi":"10.1029/2025JE009432","DOIUrl":"https://doi.org/10.1029/2025JE009432","url":null,"abstract":"<p>Detecting seismic activity on Saturn's icy moon Titan during the <i>Dragonfly</i> mission could provide crucial information on its internal structure. The geological complexity of the moon's surface suggests significant cyclic tidal deformation, likely leading to the fracturing of the ice shell. Considering realistic source locations and fault geometries, we assess whether a vertical short-period seismometer can detect body waves from a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>w</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${M}_{w}$</annotation>\u0000 </semantics></math> 4.0 icequake. Signal-to-noise ratios are evaluated by comparing the high-frequency content with the expected background noise and instrument capabilities for several ice attenuation scenarios and 1D interior models. Our results indicate that the high-frequency content (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>≥</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 <annotation> ${ge} 1$</annotation>\u0000 </semantics></math>Hz) of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>w</mi>\u0000 </msub>\u0000 <mo>≤</mo>\u0000 <mn>4.0</mn>\u0000 </mrow>\u0000 <annotation> ${M}_{w}le 4.0$</annotation>\u0000 </semantics></math> tidal-induced icequakes is likely undetectable under the most unfavorable attenuation scenarios and atmospheric conditions. However, seismic signals in the 0.5–1 Hz band—where P wave reflections dominate—may still be observable for events occurring in potential seismically active regions at ∼800–1,000 km from the <i>Dragonfly</i>'s landing site. These signals could provide constraints on the thickness of Titan's outer ice shell, provided that intrinsic attenuation is low and environmental conditions are favorable.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009432","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683109","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":"Polarization Measurements and Source Locations of Saturn Electrostatic Discharges During the Voyager Era","authors":"Masafumi Imai,&nbsp;Georg Fischer,&nbsp;Ulrich Taubenschuss,&nbsp;Ivana Kolmašová,&nbsp;Ondřej Santolík,&nbsp;David Píša","doi":"10.1029/2025JE009079","DOIUrl":"https://doi.org/10.1029/2025JE009079","url":null,"abstract":"<p>A Saturn Electrostatic Discharge or SED is an intense electromagnetic impulse induced by Saturn lightning, which escapes into space through the magnetoplasma of the ionosphere. Since previous SED polarizations from Voyager data are inconclusive, this polarization study is the first which properly considers the characteristics of the Voyager Planetary Radio Astronomy (PRA) instrument and the change of the antenna response as a function of spacecraft attitude. SED radio observations of the Cassini spacecraft from 2004 to 2017 showed a hemispheric dependence of their circular polarization sense at frequencies below 2 MHz, which can be explained by left-hand ordinary mode emissions. Here we reinvestigated the SED polarizations of the Voyager radio observations at frequencies below 1.3 MHz. As a result, we found mixed polarizations and a dominance of right-handed polarization, which is difficult to interpret in view of the Cassini result. However, we found that SEDs incident at large angles to the antenna plane (elevation angle <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>|</mo>\u0000 <mi>β</mi>\u0000 <mo>|</mo>\u0000 <mo>≥</mo>\u0000 <mn>40</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $vert beta vert ge 40{}^{circ}$</annotation>\u0000 </semantics></math>) showed a dominance of the expected left-handed polarization. We show detailed results of the SED polarization analysis and also compare them with model simulations of the Voyager PRA signal processing of short SED-like pulses. An equatorial SED source was suggested by its occurrence periodicity for both Voyagers, but imaging observations clearly detected convective clouds at 35<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N latitude. We demonstrate with Cassini data that the so-called over-the-horizon effect can mimic an equatorial periodicity, even when the single SED source is at 35<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N latitude. For Voyager 2 also equatorial clouds were imaged.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683463","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":"Testing the Limits of Provenance Analysis From Basaltic Fluvial Sediment Near Sandvatn, Iceland, as a Mars Analog","authors":"Audrey R. Putnam,&nbsp;Kirsten L. Siebach,&nbsp;Michael T. Thorpe,&nbsp;Valerie M. Tu,&nbsp;Elizabeth B. Rampe,&nbsp;Candice C. Bedford,&nbsp;Gelu Costin,&nbsp;Joseph J. Tamborski","doi":"10.1029/2025JE009400","DOIUrl":"https://doi.org/10.1029/2025JE009400","url":null,"abstract":"<p>Detrital sediments that accumulate downstream and are preserved in sedimentary rocks can allow characterization of geologic formations that are inaccessible for spatial or temporal reasons. However, mixing, sorting, and alteration of sediment during transport may complicate reconstruction of protolith characteristics. We test the preservation of three key provenance signals in coarse fluvial sand at a Mars analog watershed in Iceland to determine whether detrital sediments capture (a) watershed magmatic chemical variation, (b) textural indicators of lava-water interaction during eruption and cooling, and (c) hydrothermal alteration. Specifically, we tested whether diagnostic variations in rock mineralogy, chemistry, and texture can be recovered in the bulk mineralogy and chemistry of sand-sized sediments. In first-order basaltic fluvial sediments transported &lt;10 km, sediment sorting segregated grains with distinct inherited cooling textures and phenocrysts, and rendered some altered materials undetectable in bulk measurements of sand. This sorting also obscured signals of magmatic variability across the watershed and reduced the range of recorded lava cooling rates. The input of exogenous tephra to the Sandvatn watershed could only be distinguished in depositional environments with minimal active deposition or erosion and was most evident in reworked lakeshore deposits far from the delta. Bulk chemistry and mineralogy recorded different aspects of sediment sorting at Sandvatn, highlighting that integrating paired chemical and mineralogic data is key to disentangling the records of provenance composition and texture from sorted volcanic sediment.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683260","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":"Paleo–Stress Field Reconstructions for Veins in the Middle Murray Formation: New Evidence for Multi-Generational Deformation in Gale Crater, Mars","authors":"Morgan M. Lewis,&nbsp;Linda C. Kah,&nbsp;Bradley J. Thomson,&nbsp;Gerhard Paar","doi":"10.1029/2025JE009342","DOIUrl":"https://doi.org/10.1029/2025JE009342","url":null,"abstract":"<p>Veins, or mineral-filled rock fractures, record information about the stress conditions and fluid flow history of a rock body. Interactions between different vein sets as well as between veins and the host rock can elucidate the relative timing of fracture and vein formation and inform formation mechanisms. Widespread vein networks in Gale crater, Mars document multiple episodes of brittle rock deformation and subsurface fluid flow. In the Sutton Island and Blunts Point members of the Murray formation, at least three prominent vein sets are identified by their orientation, thickness, color, and texture: (a) thin, curviplanar (and sometimes anastomosing) veins that are typically sub-horizontal and sub-parallel to bedding; (b) thin, steeply dipping veins; and (c) thick, multicolored, steeply dipping veins. We infer hydrofracture as the mechanism for formation of the fractures in all three vein sets and provide evidence for hydrofracture formation during both exhumation and burial processes. Cross-cutting relationships indicate that sub-horizontal veins formed first followed by formation of thin, steeply dipping veins and finally, formation of thick, steeply dipping veins. This sequence of fracture and vein forming events provides a new constraint on the depositional, erosional, and diagenetic history of Mount Sharp.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683266","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":"Periodic Bedrock Ridge Formation via Shielding and Interbedform Erosion: Wind Tunnel Experiments, a Field Analog, and Survey of Mars","authors":"Mackenzie Day,&nbsp;Alana Archbold,&nbsp;Jonathan Sneed,&nbsp;Kathryn Stack Morgan,&nbsp;Abigail A. Fraeman,&nbsp;Jordan Bretzfelder","doi":"10.1029/2025JE009326","DOIUrl":"https://doi.org/10.1029/2025JE009326","url":null,"abstract":"<p>Periodic bedrock ridges (PBRs) are enigmatic landforms carved by wind on Mars. Although they have been demonstrated to be erosional features carved into lithified bedrock, the precise cause of the ridge and groove topography is not fully understood. Previous work has suggested that aeolian bedforms may have been required to form the periodicity, but some questions about this mechanism still remain. Can interbedform erosion lead to ridge-and-trough topography? To test this, we conducted a wind tunnel experiment simulating the proposed landscape formation mechanism. Additionally, we studied a field analog system where bedforms armored a hardened mud substrate. Results from these supplement observations of known and new PBR fields on Mars. The preponderance of evidence suggests that the topography derives from interbedform erosion: Bedforms shield the substrate directly beneath them, but abrasion deflates the exposed material between bedforms. Eventually, abrasion in the deflating troughs undercuts the shielding bedforms, causing them to winnow and narrow. This leads to remnant bedforms perched on ridges that separate the deepening troughs and ultimately the characteristic periodic ridge topography. This mechanism requires that the shielding bedforms' migration rate is slow with respect to the local rate of aeolian erosion. Examples of modern bedforms near periodic ridges on Mars suggest that the erosional features respond to the largest wavelengths in overlying bedform fields, filtering out the signal of small bedforms. Overall, the combined evidence from wind tunnel experiments, field work, and remote sensing supports the formation of PBRs via aeolian deflation between aeolian bedforms.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683259","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":"Interior Models of Mercury and Conditions for Iron Snow Formation in a Fe-S-Si Core","authors":"Abigail H. Dunnigan,&nbsp;Dunyu Liu,&nbsp;Gregor B. Steinbrügge,&nbsp;Attilio Rivoldini,&nbsp;Mathieu Dumberry,&nbsp;Hao Cao,&nbsp;Krista M. Soderlund","doi":"10.1029/2025JE009368","DOIUrl":"https://doi.org/10.1029/2025JE009368","url":null,"abstract":"&lt;p&gt;Mercury's unique interior structure and magnetic field generation remain to be fully understood. We construct models to further constrain Mercury's interior and test the hypothesis that iron snow within the liquid core drives the dynamo. We build upon previous models by incorporating an updated iron-sulfur-silicon (Fe-S-Si) core alloy composition and use a Monte Carlo approach to explore the parameter space consistent with geodetic and geophysical constraints. A high normalized moment of inertia (MoI) of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.346&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.014&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $0.346pm 0.014$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, in combination with thermal and geochemical constraints, favors models with an Earth-like mantle density of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;mn&gt;3300&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} 3300$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; kg/&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{m}}^{3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, an inner core &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;≤&lt;/mo&gt;\u0000 &lt;mn&gt;1050&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${le} 1050$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; km in radius, and a core silicon content of at least 6 wt%. In contrast, a lower value of MoI &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;0.333&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.005&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${=}0.333pm 0.005$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; favors models with lower mantle densities of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;mn&gt;3100&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} 3100$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; kg/&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;m&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{m}}^{3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, an inner core radius in the range of 850–1,450 km, and a core silicon content less than 8 wt%. We also show that the formation of iron snow requires a sulfur concentration gr","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"131 4","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009368","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683267","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}