Journal of Geophysical Research: Planets最新文献_第9页

Effects of Transient Obliquity Tides Within Mimas' Warm, Icy Interior Preserved as a Frozen Fossil Figure 保存为冰冻化石图的米马斯温暖冰冷的内部瞬变斜潮汐的影响

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-05-03 DOI: 10.1029/2023JE007903

S. Gyalay, F. Nimmo, B. G. Downey

{"title":"Effects of Transient Obliquity Tides Within Mimas' Warm, Icy Interior Preserved as a Frozen Fossil Figure","authors":"S. Gyalay, F. Nimmo, B. G. Downey","doi":"10.1029/2023JE007903","DOIUrl":"https://doi.org/10.1029/2023JE007903","url":null,"abstract":"Mimas has a high eccentricity and an anomalously high physical libration like its neighbor, Enceladus, but does not appear to have a geologically active surface. We investigate Mimas' interior with a technique that infers spatial variations in tidal heating from its global shape. To account for its hydrostatic shape, we find Mimas' normalized moment of inertia is 0.375 ± 0.0025, indicating a relatively undifferentiated world. Its remaining topography is consistent with a ∼30 km thick conductive ice shell in Airy isostasy atop a weakly convecting ∼30 km thick layer that itself mantles a ∼140 km radius ice-rock interior. The convective shell's density must be closer to the interior density to satisfy our moment of inertia and provide a denser compensating layer for Airy isostasy. This ice-rock interior is elongated along the Mimas-Saturn axis, which can match Mimas' observed physical libration without appealing to an ocean. The inferred ice shell thickness variations indicate a high obliquity (≈1.7°). We suggest that the obliquity damped rapidly, after which topography froze in when internal heat was conducted out of Mimas quicker than isostatic ice shell thickness variations could relax. We speculate on several possible explanations for this transient high obliquity, including excitation by ring-forming material following the recent tidal disruption of an eccentric satellite. We cannot rule out a young Mimantean ocean, but our inferred moment of inertia favors a Mimas that was solid when it experienced a period of high obliquity, did not significantly melt during a recent resonance with Enceladus, and is solid today.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140820631","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}

引用次数: 0

Velocity Measurements of Powdered Rock at Low Confining Pressures and Comparison to Lunar Shallow Seismic Velocity 低约束压力下粉末状岩石的速度测量以及与月球浅层地震速度的比较

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-05-02 DOI: 10.1029/2024JE008287

C. C. Amos, M. Prasad, K. M. Cannon, C. B. Dreyer

{"title":"Velocity Measurements of Powdered Rock at Low Confining Pressures and Comparison to Lunar Shallow Seismic Velocity","authors":"C. C. Amos, M. Prasad, K. M. Cannon, C. B. Dreyer","doi":"10.1029/2024JE008287","DOIUrl":"https://doi.org/10.1029/2024JE008287","url":null,"abstract":"Seismic methods will be useful for future lunar near-surface characterization, and high-fidelity elastic models will be required to aid interpretation of seismic observations. To develop an elastic lunar near-surface model, we performed ultrasonic velocity measurements of lunar regolith simulant at low confining pressure and developed a rock physics model calibrated to these measurements. Grain contact models based on Hertz-Mindlin theory produce accurate results at high confining pressure (i.e., several hundred meters or more burial depth) but historically fail to predict observed velocities in unconsolidated media at low pressure. Therefore, we heuristically modified existing models to fit our measured data over a range of porosities and confining pressures. To compare with Apollo 14 and 16 active seismic experiments, we used our new heuristic rock physics model to produce lunar subsurface velocity profiles. We performed ray tracing through our velocity profiles to calculate seismic traveltime, which results in good agreement with first arrivals interpreted from the Apollo experiments. Our model suggests a slightly higher velocity-pressure dependence than inferred from in situ measurements, which may be due to porosity reduction in the lunar regolith from impact-induced and natural vibrations.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008287","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140818990","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}

引用次数: 0

Reconciling Mars InSight Results, Geoid, and Melt Evolution With 3D Spherical Models of Convection 用三维球形对流模型调和火星InSight的结果、大地水准面和熔融演化

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-05-02 DOI: 10.1029/2023JE008143

J. P. Murphy, S. D. King

{"title":"Reconciling Mars InSight Results, Geoid, and Melt Evolution With 3D Spherical Models of Convection","authors":"J. P. Murphy, S. D. King","doi":"10.1029/2023JE008143","DOIUrl":"https://doi.org/10.1029/2023JE008143","url":null,"abstract":"We investigate the geodynamic and melting history of Mars using 3D spherical shell models of mantle convection, constrained by the recent InSight mission results. The Martian mantle must have produced sufficient melt to emplace the Tharsis rise by the end of the Noachian–requiring on the order of 1–3 × 109 km3 of melt after accounting for limited (∼10%) melt extraction. Thereafter, melting declined; however, abundant evidence for limited geologically recent volcanism necessitates some present-day melt even in the cool mantle inferred from InSight data. We test models with two mantle activation energies and a range of crustal Heat Producing Element (HPE) enrichment factors and initial core-mantle boundary temperatures. We also test the effect of including a hemispheric (spherical harmonic degree-1) step in lithospheric thickness to model the Martian dichotomy. We find that a higher activation energy (350 kJ mol−1) rheology produces present-day geotherms consistent with InSight results, and crustal HPE enrichment factors of 5–10-times produce localized melting near or up to present-day. The 10-times crustal HPE enrichment is consistent with both InSight and geochemical results and also produces present-day geoid power spectra consistent with Mars. However, calculations that match the present-day geoid power spectra require more than 60% melt extraction to produce the Tharsis swell. The addition of a degree-1 hemispheric dichotomy, as an equatorial step in lithospheric thickness, does not significantly improve upon melt production or the geoid.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE008143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140818988","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}

引用次数: 0

In Appreciation of Our 2023 Reviewers and Volunteers 感谢我们的 2023 年审查员和志愿者

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-05-02 DOI: 10.1029/2024JE008451

Amanda R. Hendrix, Anni Määttänen, Laurent G. J. Montési, A. Deanne Rogers, Bradley J. Thomson

{"title":"In Appreciation of Our 2023 Reviewers and Volunteers","authors":"Amanda R. Hendrix, Anni Määttänen, Laurent G. J. Montési, A. Deanne Rogers, Bradley J. Thomson","doi":"10.1029/2024JE008451","DOIUrl":"https://doi.org/10.1029/2024JE008451","url":null,"abstract":"In JGR-Planets, 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. JGR-Planets covers a broad range of topics addressing every aspect of geoscience with the only requirement that the work addresses planetary processes. The wide breadth of topics published is reflected by our editorial team composed in 2023 of associate editors Adrian Brown, Jun Cui, Joel Davis, Leigh Fletcher, Matthias Grott, Ananya Mallik, Germán Martínez, Molly McCanta, Katarina Miljkovic, Naomi Murdoch, Ryan Park, Arianna Piccialli, Andrew Poppe, Beatrix Sánchez-Cano, Laura Schaefer, Mariek Schmidt, Yasuhito Sekine, Kelsi Singer, Michael Sori, Norihiko Sugimoto, Sonia Tikoo, David Trang, and Zhiyong Xiao in addition to the editors who authored this note. We rely on the expertise of the community to vet the articles submitted to the journal. In 2023, JGR-Planets benefited from 1,184 reviews provided by 731 unique volunteer referees. We also received help from 19 guest editors working on four active special collections. To these volunteers: We are truly grateful that you chose to dedicate your time and energy to evaluate manuscripts and to advise us on the suitability of each manuscript for JGR-Planets, often suggesting ways to improve the papers. We know that all our volunteers juggle many duties, both professional and personal. On behalf of the entire editorial board of JGR-Planets, we express our heartfelt gratitude to the many scientists who support this journal. Thank you! You are performing a valued service to this journal and to the community.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008451","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140818989","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}

引用次数: 0

Manganese-Rich Sandstones as an Indicator of Ancient Oxic Lake Water Conditions in Gale Crater, Mars 富锰砂岩是火星盖尔陨坑古代缺氧湖泊水条件的指示物

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-05-01 DOI: 10.1029/2023JE007923

P. J. Gasda, N. L. Lanza, P.-Y. Meslin, S. N. Lamm, A. Cousin, R. Anderson, O. Forni, E. Swanner, J. L’Haridon, J. Frydenvang, N. Thomas, S. Gwizd, N. Stein, W. W. Fischer, J. Hurowitz, D. Sumner, F. Rivera-Hernández, L. Crossey, A. Ollila, A. Essunfeld, H. E. Newsom, B. Clark, R. C. Wiens, O. Gasnault, S. M. Clegg, S. Maurice, D. Delapp, A. Reyes-Newell

{"title":"Manganese-Rich Sandstones as an Indicator of Ancient Oxic Lake Water Conditions in Gale Crater, Mars","authors":"P. J. Gasda, N. L. Lanza, P.-Y. Meslin, S. N. Lamm, A. Cousin, R. Anderson, O. Forni, E. Swanner, J. L’Haridon, J. Frydenvang, N. Thomas, S. Gwizd, N. Stein, W. W. Fischer, J. Hurowitz, D. Sumner, F. Rivera-Hernández, L. Crossey, A. Ollila, A. Essunfeld, H. E. Newsom, B. Clark, R. C. Wiens, O. Gasnault, S. M. Clegg, S. Maurice, D. Delapp, A. Reyes-Newell","doi":"10.1029/2023JE007923","DOIUrl":"https://doi.org/10.1029/2023JE007923","url":null,"abstract":"Manganese has been observed on Mars by the NASA Curiosity rover in a variety of contexts and is an important indicator of redox processes in hydrologic systems on Earth. Within the Murray formation, an ancient primarily fine-grained lacustrine sedimentary deposit in Gale crater, Mars, have observed up to 45× enrichment in manganese and up to 1.5× enrichment in iron within coarser grained bedrock targets compared to the mean Murray sediment composition. This enrichment in manganese coincides with the transition between two stratigraphic units within the Murray: Sutton Island, interpreted as a lake margin environment, and Blunts Point, interpreted as a lake environment. On Earth, lacustrine environments are common locations of manganese precipitation due to highly oxidizing conditions in the lakes. Here, we explore three mechanisms for ferromanganese oxide precipitation at this location: authigenic precipitation from lake water along a lake shore, authigenic precipitation from reduced groundwater discharging through porous sands along a lake shore, and early diagenetic precipitation from groundwater through porous sands. All three scenarios require highly oxidizing conditions and we discuss oxidants that may be responsible for the oxidation and precipitation of manganese oxides. This work has important implications for the habitability of Mars to microbes that could have used Mn redox reactions, owing to its multiple redox states, as an energy source for metabolism.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE007923","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140817265","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}

引用次数: 0

Low But Persistent Organic Carbon Content of Hyperarid River Deposits and Implications for Ancient Mars 超干旱河流沉积物中低但持久的有机碳含量及其对古火星的影响

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-04-30 DOI: 10.1029/2023JE008182

H. Kalucha, M. M. Douglas, M. P. Lamb, Y. Ke, W. W. Fischer

{"title":"Low But Persistent Organic Carbon Content of Hyperarid River Deposits and Implications for Ancient Mars","authors":"H. Kalucha, M. M. Douglas, M. P. Lamb, Y. Ke, W. W. Fischer","doi":"10.1029/2023JE008182","DOIUrl":"https://doi.org/10.1029/2023JE008182","url":null,"abstract":"Mars has many well-exposed fluvial ridges and fluvio-deltaic basins; in two of these locations, the Curiosity and Perseverance rovers are currently searching for signs of habitability. The distribution of organic carbon that might persist in ancient fluvial deposits present on Mars is not well understood. In this study, we set out to assess the preservation potential of organic carbon in a hyperarid fluvial environment with observations and analyses of the Amargosa River in Death Valley, California (United States). The lower reaches of the Amargosa River in Badwater Basin are nearly devoid of plants and contain low gradient, meandering channels, making them a valuable terrestrial analog for early martian fluvial systems. We analyzed sediment taken from fluvial deposits exposed in cutbanks of two bends of a meandering channel. We found total organic carbon abundances that were on average 0.15% up to a meter below the surface. X-ray diffraction and electron microscopy analyses revealed a suite of high redox potential mineral phases (including iron and manganese oxides) mixed with detrital and authigenic silicates, carbonate, and sulfate salts at or close to redox equilibrium with pore fluids in contact with the atmosphere. This finding highlighted that organic carbon can persist in fluvial deposits at low abundance despite oxidizing conditions and saturated sediments and suggested that ancient fluvial deposits on Mars may retain traces of organics in fine-grained deposits if they are present during deposition.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140814170","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}

引用次数: 0

Insights Into Venus' Crustal Plateaus From Dyke Trajectories Below Craters 从陨石坑下的堤坝轨迹洞察金星地壳台地

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-04-30 DOI: 10.1029/2023JE008189

Alexandra Le Contellec, Chloé Michaut, Francesco Maccaferri, Virginie Pinel, Frédéric Chambat, Suzanne Smrekar

{"title":"Insights Into Venus' Crustal Plateaus From Dyke Trajectories Below Craters","authors":"Alexandra Le Contellec, Chloé Michaut, Francesco Maccaferri, Virginie Pinel, Frédéric Chambat, Suzanne Smrekar","doi":"10.1029/2023JE008189","DOIUrl":"https://doi.org/10.1029/2023JE008189","url":null,"abstract":"On Venus, radar observations of the surface have highlighted two categories of craters: bright-floored, interpreted as pristine, and dark-floored, interpreted as being partially filled by lava. While volcanic resurfacing occurs within and outside craters in the plains, it seems mainly concentrated within the interior of dark-floored craters in the crustal plateaus, suggesting that the magma is negatively buoyant there. Indeed, crater unloading may facilitate vertical ascent of a negatively buoyant magma by decompressing the underlying crust. However, the crater topography also generates a shear stress which would tend to horizontalize the vertical propagation of a dyke. We use numerical simulations of magma ascent in an axisymmetric crater stress field to demonstrate that, depending on the crust thickness and the magma-crust density contrast, a negatively buoyant magma can indeed erupt only in the crater interior while remaining stored in the crust elsewhere. In particular, we identify four different behaviors depending on if and where a magma-filled crack ascending below a crater reaches the surface. We draw a regime diagram as a function of two characteristic dimensionless numbers. For eruption to occur only in the crater interior requires a crust thinner than 45 km and a limited range of magma-crust density contrasts, between 40 and 280 kg m−3 for crust thicknesses between 20 and 45 km, the permissible range decreasing for increasing crustal thicknesses. These results suggest that the crustal plateaus may not be particularly thick and could be slightly differentiated, but probably not very felsic.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE008189","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140814222","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}

引用次数: 0

Compositional Remote Sensing and Hyperspectral Laboratory Analyses of Sinters in Hydrothermal Fields in Chile, With Relevance to Astrobiological Targets on Mars 对智利热液场中沉积物的成分遥感和高光谱实验室分析，与火星上的天体生物学目标有关

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-04-30 DOI: 10.1029/2023JE007999

R. L. Cheng, J. R. Michalski, K. A. Campbell

{"title":"Compositional Remote Sensing and Hyperspectral Laboratory Analyses of Sinters in Hydrothermal Fields in Chile, With Relevance to Astrobiological Targets on Mars","authors":"R. L. Cheng, J. R. Michalski, K. A. Campbell","doi":"10.1029/2023JE007999","DOIUrl":"https://doi.org/10.1029/2023JE007999","url":null,"abstract":"Siliceous hot spring deposits, or sinters, deposit from hot spring discharge at Earth's surface and are sites of exceptional preservation of biosignatures. Their macro- and micro-textures are regarded as important evidence of past microbial activities in hydrothermal environments. However, biology mimics do occur, and bona fide microbial textures could be destroyed by subsequent diagenesis or other post-depositional processes. Thus, it is paramount to narrow the search for prospective Martian silica-rich deposits that may contain biosignatures from both orbital and rover-based perspectives. This study investigates hydrothermal deposits in Chile, which are analogs of high-silica deposits discovered in the Gusev crater on Mars, through remote sensing and laboratory analysis. Results indicate that compositional remote sensing based on multispectral data with a high spatial resolution of <4 m/pixel reflects various concentrations of silica, which assisted in identifying the direction of discharged hydrothermal flows from the vent to the apron. Micro-infrared mapping of sinters from similar hydrothermal fields linked spectral features to specific textures revealed by scanning electron microscope and chemical compositions confirmed by electron microprobe analysis, indicating that sinters with no shift in their emissivity minimum in the thermal infrared range were more likely to preserve cellular structures. An instrument for collecting multispectral data with higher spatial resolution could aid in characterizing the geologic settings of potential hot springs on Mars. Locating emissivity minima in the infrared regions of silica that do not shift to a lower position would suggest the potential for well-preserved microbial structures in Martian sinters, if life ever did exist there.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE007999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140814223","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}

引用次数: 0

Effect of Target Layering in Gravity-Dominated Cratering in Nature, Experiments, and Numerical Simulations 自然、实验和数值模拟中重力主导型 Cratering 的靶层效应

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-04-26 DOI: 10.1029/2023JE008110

J. Ormö, S. D. Raducan, K. R. Housen, K. Wünnemann, G. S. Collins, A. P. Rossi, I. Melero-Asensio

{"title":"Effect of Target Layering in Gravity-Dominated Cratering in Nature, Experiments, and Numerical Simulations","authors":"J. Ormö, S. D. Raducan, K. R. Housen, K. Wünnemann, G. S. Collins, A. P. Rossi, I. Melero-Asensio","doi":"10.1029/2023JE008110","DOIUrl":"https://doi.org/10.1029/2023JE008110","url":null,"abstract":"Impacts into layered targets may generate “concentric craters” where a wider outer crater in the top layer surrounds a smaller, nested crater in the basement, which itself may be complex or simple. The influence of target on cratering depends on the ratio of target strength to lithostatic stress, which, in turn, is affected by gravity, target density, and crater diameter. When this ratio is large, the crater size is primarily determined by target strength, whereas gravitational forces dominate when the ratio is small. In two-layer targets, strength may dominate in one or both layers, whereby the outer crater develops in the weaker top layer and the nested crater in the stronger substrate. However, large natural craters that should be gravity-dominated in both cover strata and substrate may be concentric, the reasons for which are not yet fully understood. We performed qualitative impact experiments at 10–502 G and 1.8 km/s with the Boeing Corp. Hypervelocity centrifuge gun, and at 1 G and 0.4 km/s with the CAB CSIC-INTA gas gun into layered sand targets of different compositions and grain densities but similar granulometry to analyze gravity-dominated cratering. The results are compared with iSALE-2D numerical simulations and natural craters on Earth and Mars. We show that target layering also affects the excavation process and concentric crater formation in gravity-dominated impacts. The most important factors are the density and internal friction of each target layer, respectively. We propose that this is also valid for natural craters of sizes that should make their formation gravity-dominated.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140648146","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}

引用次数: 0

Spherical-Harmonic Distribution Analysis of Coronae in Relation to Volcanic Features on Venus 与金星火山特征有关的日冕的球形谐波分布分析

IF 4.8 1区地球科学

Journal of Geophysical Research: Planets Pub Date : 2024-04-26 DOI: 10.1029/2023JE008219

Wesley S. Tucker, Andrew J. Dombard

{"title":"Spherical-Harmonic Distribution Analysis of Coronae in Relation to Volcanic Features on Venus","authors":"Wesley S. Tucker, Andrew J. Dombard","doi":"10.1029/2023JE008219","DOIUrl":"https://doi.org/10.1029/2023JE008219","url":null,"abstract":"Venus boasts an abundance of volcanoes and volcano-like structures. Synthetic aperture radar images of the surface have revealed extensive evidence of volcanism, including lava flows and edifices. Volcanic activity is further supported by crater statistics, and analysis of topography and gravity data. Unique to Venus, coronae are quasi-circular volcano-tectonic features exhibiting diverse volcanic characteristics. Despite this, volcanism is often under-represented in formation models. We identify a new subset of coronae that display topographic changes subsequent to the emplacement of lava flows within their fracture annuli, pointing to the critical role of volcanic and magmatic processes in the formation of these coronae. Through spherical-harmonic distribution analysis, we find that this new subset is spatially related to the full coronae database, pointing to an intrinsic process of coronae formation. Furthermore, coronae exhibit strong correlations and similar spectral shapes at low spherical harmonic degrees with large volcanoes, suggesting a shared geodynamic origin. Our findings underscore the pivotal role of volcanism in coronae formation and highlight the need for future research to integrate magmatic and volcanic processes more comprehensively into geophysical models. Such models would better capture the complex interactions between volcanic emplacement, magmatic activity, and lithospheric dynamics on Venus.","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JE008219","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140648147","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}

引用次数: 0