Journal of Geophysical Research: Planets最新文献

{"title":"The Seismogenic Thickness of Venus","authors":"Julia S. Maia,&nbsp;Ana-Catalina Plesa,&nbsp;Iris van Zelst,&nbsp;Richard Ghail,&nbsp;Anna J. P. Gülcher,&nbsp;Mark P. Panning,&nbsp;Sven Peter Näsholm,&nbsp;Barbara De Toffoli,&nbsp;Anna C. Horleston,&nbsp;Krystyna T. Smolinski,&nbsp;Sara Klaasen,&nbsp;Robert R. Herrick,&nbsp;Raphael F. Garcia","doi":"10.1029/2025JE009065","DOIUrl":"https://doi.org/10.1029/2025JE009065","url":null,"abstract":"<p>Growing evidence that volcanism is currently ongoing on Venus suggests that the sister planet of the Earth may also be seismically active. Given the success of seismic measurements on Mars and the Moon to reveal the interior structure of these bodies, seismic investigations on Venus are a natural next step. The potential for seismic activity is closely linked to the thickness of the so-called seismogenic layer, that is, the region where rocks behave in a brittle manner and quakes can nucleate. On Earth, the seismogenic thickness is correlated with the thermal structure of the lithosphere, and is typically associated with the depth of the 600°C isotherm. Here, we combine geophysical constraints with thermal evolution models to estimate the thermal structure of Venus' lithosphere and determine the corresponding seismogenic thickness. Taking all estimates into account, our results show that the seismogenic thickness overall varies from 2 to 35 km. The lowest values are associated with areas that probably correspond to local thermal anomalies associated with magmatic processes. This interpretation is corroborated by geodynamic models, which show that intrusive magmatism can largely increase the temperature within the lithosphere at local scales. The seismogenic layer is thickest at volcanic plains which are commonly associated with regions of mantle downwellings. In these regions, the seismogenic layer likely reaches Venus' mantle, while in areas with a thick crust or anomalously high thermal gradients, quakes might be limited to the crust. Our study provides evidence that Venus has a substantial seismic potential.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606515","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 New Experimental Setup for High-Temperature Dielectric Characterization of Venus Analogs","authors":"Jamaledin Baniamerian,&nbsp;Sebastian E. Lauro,&nbsp;Barbara Cosciotti,&nbsp;Alessandro Brin,&nbsp;Carlo Lefevre,&nbsp;Elisabetta Mattei,&nbsp;Elena Pettinelli","doi":"10.1029/2024JE008545","DOIUrl":"https://doi.org/10.1029/2024JE008545","url":null,"abstract":"<p>Radar sounder investigations of Venus' crust are particularly challenging, due to the expected high loss character of the rocks at temperatures of hundreds of degrees. The dielectric behavior of hot planetary analogues is poorly understood, as the procedure to measure such samples is difficult, especially in the frequency range of 1–100 MHz typical of planetary radar sounders. In this paper a new experimental setup capable of measuring the complex dielectric permittivity of rock slices at temperatures as high as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>50</mn>\u0000 <mrow>\u0000 <mn>0</mn>\u0000 </mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $500{}^{circ}$</annotation>\u0000 </semantics></math>C, in a large frequency range is presented. The measurements are based on the open-ended coaxial transmission line approach, where the sample is kept inside an oven to reach thermal equilibrium, and the probe tip is placed in contact with the rock and rapidly removed to limit heat propagation along the probe. The dielectric quantities (real part of permittivity and loss tangent) are computed by inverting the scattering parameters measured with a Vector Network Analyzer. Experimental data are compared with electromagnetic simulations, to define the probe characteristics and its criticalities. To assess the reliability of the setup, the results are validated using Macor ceramic samples for which dielectric properties have been measured and certified at different temperatures and frequencies. The methodology is then applied to a basaltic rock sample to demonstrate its applicability to potential Venusian analogues. The proposed technique instills confidence in the possibility of exploring the complex permittivity parameter space of many igneous and sedimentary rocks at high temperatures.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606518","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":"Atmospheric CO2 Ice in the Martian Polar Regions: Physical and Spectral Properties From Mars Climate Sounder Observations","authors":"R. W. Stevens,&nbsp;P. O. Hayne,&nbsp;A. Kleinböhl,&nbsp;D. M. Kass","doi":"10.1029/2025JE008956","DOIUrl":"https://doi.org/10.1029/2025JE008956","url":null,"abstract":"&lt;p&gt;&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; ice clouds are important for polar energy balance and the carbon dioxide cycle on Mars. However, uncertainties remain regarding their physical and radiative properties, which control how polar &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; clouds interact with the global Martian climate. Here, we use Mars Climate Sounder (MCS) observations of atmospheric radiance to estimate these physical and radiative properties. We find that Martian &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; clouds are typically composed of large particles from a narrow size distribution with an effective radius of 46 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;μ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${upmu }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;m and an effective variance of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2.0&lt;/mn&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $2.0times 1{0}^{-3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; in the southern hemisphere, and an effective radius of 42 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;μ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${upmu }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;m and an effective variance of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2.0&lt;/mn&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE008956","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606517","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":"Melting of Phyllosilicates and Evolution of Impact Glasses in Simulated Cratering Events","authors":"Qi Sun,&nbsp;Yu-Yan Sara Zhao,&nbsp;Kesong Ni,&nbsp;Zonghao Wang,&nbsp;Wen Yu,&nbsp;Wenqi Luo,&nbsp;Wenbin Yu,&nbsp;Xin Nie,&nbsp;Zonghua Qin,&nbsp;Quan Wan","doi":"10.1029/2025JE009023","DOIUrl":"https://doi.org/10.1029/2025JE009023","url":null,"abstract":"<p>Impact events involving phyllosilicates, whether present in targets or impactors, are highly probable on various celestial bodies. While impact melting is considered the most important metamorphic feature in shocked phyllosilicates, lack of understanding of this process represents a substantial impediment to constraining shock conditions from melted phyllosilicates and to inferring surface evolution of celestial bodies. To investigate shock metamorphism of phyllosilicates, cratering experiments were conducted on clinochlore targets using a light-gas gun at impact velocities ranging from 0.8 to 7.0 km·s⁻¹, and the shocked fragments were characterized with electron microscopy, X-ray diffraction (XRD), Raman spectroscopy and near-infrared spectroscopy. Clinochlore underwent melting at a low velocity of 0.8 km·s⁻¹ due to localized energy concentration at the micron-scale projectile-target interface. With increasing velocity up to 7.0 km·s⁻¹, the shock-generated glasses evolved from semi-parallel nanofilaments to complex agglutinate-like layers, within which abundant vesicles were present due to shock-induced dehydroxylation. Submicroscopic metallic particles were pervasive in the agglutinate-like layers, possibly owing to melting and solidification of micro-jetted metallic fragments. In line with the morphological characterization results, XRD patterns, near-infrared reflectance spectra and Raman spectra of the shocked fragments also collectively reflect the presence and evolution of the impact glasses. Beneath the impact glasses, shock metamorphism may be indicated by decreased basal spacings of clinochlore in the unmelted matrices. Additionally, olivine bearing exogenous iron composition from projectiles crystallized from high-temperature melts during secondary impacts. This work may provide important constraints for regolith evolution and impact history of extraterrestrial bodies.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606516","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":"Symmetric Instability in a Boussinesq Fluid on a Rotating Planet","authors":"Yaoxuan Zeng,&nbsp;Malte F. Jansen","doi":"10.1029/2025JE009115","DOIUrl":"https://doi.org/10.1029/2025JE009115","url":null,"abstract":"&lt;p&gt;Symmetric instability has broad applications in geophysical and planetary fluid dynamics. It plays a crucial role in the formation of mesoscale rainbands at mid-latitudes on Earth, instability in the ocean's mixed layer, and slantwise convection on gas giants and icy moon oceans. Here, we apply linear instability analysis to an arbitrary zonally symmetric Boussinesq flow on a rotating spherical planet, with applicability to icy moon oceans. We divide the instabilities into three types: (a) gravitational instability, occurring when stratification is unstable along angular momentum surfaces, (b) inertial instability, occurring when angular momentum shear is unstable along buoyancy surfaces, and (c) a mixed symmetric instability, occurring when neither of the previous conditions are fulfilled, but the potential vorticity has the opposite sign to planetary rotation. We note that &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${N}^{2}&lt; 0$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; where &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $N$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is the Brunt–Väisälä frequency—a typical criterion used to trigger convective adjustment in global ocean models—is neither necessary nor sufficient for instability. Instead, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;mi&gt;z&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mi&gt;sin&lt;/mi&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${b}_{z},sin {theta }_{0}&lt; 0$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, where &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;mi&gt;z&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${b}_{z}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is the stratification along the planetary rotation axis and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009115","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144606453","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":"Surface Dust Coverages on Rock Targets in Gale Crater: Influence of Elevation, Proximity to Aeolian Sand Fields and Seasonality","authors":"T. L. J. Henley,&nbsp;M. E. Schmidt,&nbsp;K. W. Lewis,&nbsp;J. E. Moores,&nbsp;C. Hayes,&nbsp;S. L. Bray,&nbsp;N. J. Bradley,&nbsp;R. E. Lee,&nbsp;I. K. Marincic,&nbsp;K. W. Turner,&nbsp;S. D. Guzewich,&nbsp;C. E. Newman,&nbsp;G. Bischof,&nbsp;D. Viúdez-Moreiras","doi":"10.1029/2023JE008184","DOIUrl":"https://doi.org/10.1029/2023JE008184","url":null,"abstract":"<p>Martian dust is mobilized throughout the year by local, regional, and global dust storms, influencing atmospheric opacity and inhibiting observations of the surface. Using Mars Hand Lens Imager (MAHLI) images and methods of Schmidt et al. (2018), https://doi.org/10.1029/2018je005553, areal dust coverages on 368 near-horizontal, undisturbed rock surfaces were estimated along six Mars Years of the Mars Science Laboratory (MSL) <i>Curiosity</i> rover's geologic traverse from mission sols 46–3,409, corresponding to Mars Year 31 (MY#; Clancy et al., 2000, https://doi.org/10.1029/1999JE001089), areocentric solar longitude (Ls) 175.9° through MY36, Ls 177.6°. Targets were evaluated for potential geospatial and seasonal (Ls) correlations. Dust coverages increased at each spring equinox (Ls = 0°) with the highest coverage (76.6%) recorded at the top of Vera Rubin Ridge (VRR) prior to the Mars Year 34 (MY34) global dust storm. Dust coverages annually decreased as prevailing wind strengths in the Gale crater increased during southern summer. Following the ascent of VRR, New Year maximums have decreased by approximately 15% annually (MY35 60.7%, and MY36 52.8%), suggesting that dust is less abundant at higher elevations on Mount Sharp, and/or that dust suspension or removal is enhanced at higher elevations by stronger winds at higher elevations. Two regions with relatively low dust coverages (&lt;20%) were found in proximity to active aeolian sand dunes and are interpreted to result from saltating sand particles striking and lofting dust particles. This research represents the single longest recording of surface dust deposits to date for landed missions.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE008184","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589641","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":"Crystalline Ferroan Anorthosite Identified in the Lunar Apollo Basin","authors":"Dijun Guo,&nbsp;Yeming Bao,&nbsp;Xing Wu,&nbsp;Shuai Li,&nbsp;Yang Liu,&nbsp;Yazhou Yang,&nbsp;Yuchen Xu,&nbsp;Feng Zhang,&nbsp;Jianzhong Liu,&nbsp;Yongliao Zou","doi":"10.1029/2024JE008690","DOIUrl":"https://doi.org/10.1029/2024JE008690","url":null,"abstract":"<p>Ferroan anorthosite, the dominant component of the primordial lunar crust, provides valuable evidence for the lunar magma ocean (LMO) theory. Despite its adjacency to the feldspathic highlands terrane, the identification of pure anorthosite in the Apollo basin has been scarce. Through a comprehensive investigation with high-resolution Kaguya Multiband Imager data over the Apollo basin, we identified numerous outcrops exhibiting definitive diagnostic absorption indicative of the presence of ferroan anorthosite. These anorthosite exposures suggest that crustal material remained after the South Pole-Aitken (SPA) basin impact and that the mafic-rich SPA ejecta was thin in the area, providing significant insights into the excavation process of the SPA impact and subsequent evolution. Our results suggest that the Chang'e-6 mission could potentially bring back the primordial crustal anorthosite from the Apollo basin and offer valuable insights into the LMO theory, alongside the mantle material excavated by the massive SPA impact.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144589642","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":"Conjugated Silicate Nanodroplets in Lunar Regolith: Unraveling Impact-Driven Phase Separation","authors":"Yiheng Dai,&nbsp;Zhiheng Xie,&nbsp;Zezhou Li,&nbsp;Tianyi Jia,&nbsp;Ruimin Wang,&nbsp;Zongjun Yin,&nbsp;Bing Shen,&nbsp;Jihan Zhou","doi":"10.1029/2025JE009028","DOIUrl":"https://doi.org/10.1029/2025JE009028","url":null,"abstract":"<p>Meteoroid impacts, a key process of space weathering, significantly alter the structures, compositions and properties of lunar regolith. However, the phase separation phenomena, common in lunar regolith and induced by impact, remain poorly understood. This uncertainty arises from the structural complexity and the scarcity of identified impact-induced phase separation features. Here we report the impact-induced formation of chemically distinct amorphous silicate nanodroplets, including iron-rich droplets within a silicon-rich glass matrix and vice versa, on the surface of a Chang'e-5 lunar regolith grain. These nanodroplets are partially ripened aggregates, and their formation is attributed to metastable liquid immiscibility driven by local chemical heterogeneities and rapid quenching. Additionally, troilite-kamacite remnants and skeletal crystallites of ilmenite and apatite provide direct evidence of impact and fast post-impact quenching, respectively. These findings suggest that quenched impact melts in airless bodies can undergo unmixing, forming immiscible conjugated nanodroplets, and exhibiting diverse behaviors under specific post-impact conditions.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144582190","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":"Preferential Formation and Efficient Preservation of Perchlorate With Iron Salts on the Martian Surface","authors":"Shuai-Yi Qu,&nbsp;Yu-Yan Sara Zhao,&nbsp;He Cui,&nbsp;Shuai Zhang,&nbsp;Xiuqin Yang,&nbsp;Honglei Lin,&nbsp;Chao Qi,&nbsp;Xiongyao Li,&nbsp;Jianzhong Liu","doi":"10.1029/2024JE008688","DOIUrl":"https://doi.org/10.1029/2024JE008688","url":null,"abstract":"<p>Chlorine-bearing salts mixed with other minerals exposed to ultraviolet light participate in chlorine redox cycles on the Martian surface. Previous studies have shown that Fe^III sulfates can exclusively produce perchlorate by chloride photooxidation, but the mechanisms and effective scopes remain unclear. In this study, we investigated this perspective by conducting two main photochemical experiments using ultraviolet light 254 nm. Chloride oxidation experiments examined the effects of different Fe minerals (i.e., Fe^II sulfates, Fe^III sulfates, Fe^III chlorides, Fe^III nitrates, pyrrhotite, siderite and nontronite) and acidified non-Fe sulfates (Ca-, Mg-, Na-, and K- sulfates). Photocatalytic conversion experiments assessed the conversion products of perchlorate and chlorate in the presence of different sulfates (Fe^III, Ca, Mg, Na, and K). Our results showed that the ClO₃⁻/ClO₄⁻ molar ratios &lt;&lt;1 reported for Fe^III sulfates did not occur in any non-Fe sulfates, even after acidification by concentrated H₂SO₄. Other Fe salts, such as Fe^II sulfates, Fe^III nitrates, and Fe^III chlorides, also showed preferential ClO₄⁻ production, whereas pyrrhotite, siderite and nontronite produced more ClO₃⁻ than ClO₄⁻. Photocatalytic conversion experiments starting with NaClO₃ and NaClO₄ demonstrated that Fe^III can facilitate the direct NaClO₃-to-NaClO₄ conversion without producing Cl⁻ and inhibit the photolysis of NaClO₄. Our study highlights the unique role of hygroscopic Fe salts (both Fe^II and Fe^III) in the production and preservation of perchlorate. Mineral surfaces and water vapor may play essential roles in the chlorine redox cycle. The likely coexistence of perchlorate and Fe^III salts has important implications for liquid water on the present cold and arid Mars.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573226","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":"Observed Latitudinal, Longitudinal and Temporal Variability of Io's Atmosphere Simulated by a Purely Sublimation Driven Atmosphere","authors":"A.-C. Dott,&nbsp;J. Saur,&nbsp;S. Schlegel,&nbsp;D. F. Strobel,&nbsp;K. de Kleer,&nbsp;I. de Pater","doi":"10.1029/2024JE008869","DOIUrl":"https://doi.org/10.1029/2024JE008869","url":null,"abstract":"&lt;p&gt;How much of Io's &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;SO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{SO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; atmosphere is driven by volcanic outgassing or sublimation of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;SO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{SO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; surface frost is a question with a considerable history. We develop a time dependent surface temperature model including thermal inertia and the exact celestial geometry to model the radiation driven global structure and temporal evolution of Io's atmosphere. We show that many observations can be explained by assuming a purely sublimation driven atmosphere. We find that a thermal diffusivity &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;α&lt;/mi&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;2.41&lt;/mn&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;7&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $alpha =2.41times 1{0}^{-7}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; &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;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{m}}^{2}{mathrm{s}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; yields an averaged atmospheric &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;SO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{SO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; column density decreasing by more than one order of magnitude from the equator to the poles in accordance with the observed spatial variations of Io's column densities. Our model produces a strong day-night-asymmetry with modeled column density variations of almost two orders of magnitude at the equator as well as a sub-anti-Jovian hemis","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"130 7","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008869","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564126","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}