Jun Du, David A. Minton, Austin M. Blevins, Caleb I. Fassett, Ya-Huei Huang
The morphology of fresh lunar craters contains information about the physical properties of both the impactors and the lunar surface, and is therefore crucial to our knowledge of the impact cratering process. Spectral analysis is a powerful tool to study crater morphology, as it can reveal the topographic variation on different scales. In this study, we calculate the power spectral densities of the radial distance and elevation of the rim crest, floor, and rim flank outlines of fresh lunar craters. The resulting power spectral density can be decomposed into an average component and a natural variability component. For the average component, we derive the classic morphometric parameter-crater diameter relations that are consistent with previous studies. For the natural variability component, we find that in general the spectral power increases with wavelength, which can be fitted by a piecewise function with four breakpoints. Among the four breakpoints, the power of the third breakpoint (i.e., the degree-2 power) is of particular interest, as it determines the ellipticity of the outline. The power of the third breakpoint is found to have a diameter dependence with a peak at 20 km, which indicates that transitional craters are more elliptical than simple and complex craters. The diameter dependence of the power spectral density enables us to generate the synthetic outlines of a crater of a particular size, which can be used to develop a preliminary 3-dimensional shape model for fresh lunar craters that is useful for improving Monte Carlo modeling of cratered surfaces on the Moon.
{"title":"Spectral Analysis of the Morphology of Fresh Lunar Craters I: Rim Crest, Floor, and Rim Flank Outlines","authors":"Jun Du, David A. Minton, Austin M. Blevins, Caleb I. Fassett, Ya-Huei Huang","doi":"10.1029/2024JE008357","DOIUrl":"https://doi.org/10.1029/2024JE008357","url":null,"abstract":"<p>The morphology of fresh lunar craters contains information about the physical properties of both the impactors and the lunar surface, and is therefore crucial to our knowledge of the impact cratering process. Spectral analysis is a powerful tool to study crater morphology, as it can reveal the topographic variation on different scales. In this study, we calculate the power spectral densities of the radial distance and elevation of the rim crest, floor, and rim flank outlines of fresh lunar craters. The resulting power spectral density can be decomposed into an average component and a natural variability component. For the average component, we derive the classic morphometric parameter-crater diameter relations that are consistent with previous studies. For the natural variability component, we find that in general the spectral power increases with wavelength, which can be fitted by a piecewise function with four breakpoints. Among the four breakpoints, the power of the third breakpoint (i.e., the degree-2 power) is of particular interest, as it determines the ellipticity of the outline. The power of the third breakpoint is found to have a diameter dependence with a peak at 20 km, which indicates that transitional craters are more elliptical than simple and complex craters. The diameter dependence of the power spectral density enables us to generate the synthetic outlines of a crater of a particular size, which can be used to develop a preliminary 3-dimensional shape model for fresh lunar craters that is useful for improving Monte Carlo modeling of cratered surfaces on the Moon.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008357","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664786","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}
Chaoqun Zhang, Xiaoguang Niu, Lixin Gu, Xu Tang, Yi Chen, Changrun Cai, Yanchao Dai, Gen Li, Hongping He, Yongxin Pan, Zhigang Zhang, Jinhua Li
Space weathering records provide insights to better understand the formation and evolution of the lunar regolith. Ilmenite has contrasting responses to different space weathering processes. However, the atomic-scale structural modification of ilmenite induced using different space weathering processes remains poorly understood. Here, we investigate the effects of spacing weathering on lunar ilmenite grains returned from Chang'e-5 (CE-5) mission using a combination of transmission electron microscopy and thermodynamic modeling approaches. Experimental results show that melt shock induces the formation of twining structures and vein-like Si-Ca-rich nanostructures in the outermost and sub-outermost layers of ilmenite, respectively. In contrast, solar wind causes the formation of multilayered nanostructures surrounding the ilmenite grains. These structures are characterized by an outermost amorphous Si-rich vapor deposited layer, a middle layer rich in titanium (Ti) oxides and zero-valent iron (Fe0) nanoparticles, and an innermost layer hosting crystallographic orientation defect. The Ti oxides were identified as poorly crystallized anatase. Thermodynamic calculations indicate that the disruptive sputtering of solar wind and the reduction of hydrogen under lunar surface pressure conditions can promote ilmenite transformation into Fe0 and Ti oxides; nevertheless, the pressure increase associated with melt shock can lead to a rise in the decomposition temperature of ilmenite. In other words, solar wind irradiation plays a more significant role in promoting nanoparticle (such as anatase and Fe0) formation as compared to melt shock. Thus, unlike the chemical alteration of ilmenite induced by the solar wind irradiation, melt shock mainly causes physical changes in ilmenite grains.
空间风化记录为更好地了解月球风化岩的形成和演变提供了启示。钛铁矿对不同空间风化过程的反应截然不同。然而,人们对不同空间风化过程引起的钛铁矿原子尺度结构变化仍然知之甚少。在此,我们采用透射电子显微镜和热力学建模相结合的方法,研究了嫦娥五号(CE-5)任务返回的月球钛铁矿晶粒的间距风化效应。实验结果表明,熔融冲击分别在钛铁矿的最外层和次最外层诱导形成了缠绕结构和富含Si-Ca的脉状纳米结构。相比之下,太阳风会在钛铁矿晶粒周围形成多层纳米结构。这些结构的特点是:最外层是富含硅的无定形气相沉积层,中间层富含钛(Ti)氧化物和零价铁(Fe0)纳米颗粒,最内层则存在晶体取向缺陷。钛氧化物被鉴定为结晶度较差的锐钛矿。热力学计算表明,太阳风的破坏性溅射和月球表面压力条件下的氢还原可促进钛铁矿转化为 Fe0 和 Ti 氧化物;然而,与熔融冲击相关的压力增加会导致钛铁矿的分解温度升高。换句话说,与熔融冲击相比,太阳风辐照在促进纳米粒子(如锐钛矿和 Fe0)形成方面发挥着更重要的作用。因此,与太阳风辐照引起的钛铁矿化学变化不同,熔融冲击主要引起钛铁矿晶粒的物理变化。
{"title":"Atomic-Level Structural Responses of Chang'e-5 Ilmenite to Space Weathering","authors":"Chaoqun Zhang, Xiaoguang Niu, Lixin Gu, Xu Tang, Yi Chen, Changrun Cai, Yanchao Dai, Gen Li, Hongping He, Yongxin Pan, Zhigang Zhang, Jinhua Li","doi":"10.1029/2024JE008447","DOIUrl":"https://doi.org/10.1029/2024JE008447","url":null,"abstract":"<p>Space weathering records provide insights to better understand the formation and evolution of the lunar regolith. Ilmenite has contrasting responses to different space weathering processes. However, the atomic-scale structural modification of ilmenite induced using different space weathering processes remains poorly understood. Here, we investigate the effects of spacing weathering on lunar ilmenite grains returned from Chang'e-5 (CE-5) mission using a combination of transmission electron microscopy and thermodynamic modeling approaches. Experimental results show that melt shock induces the formation of twining structures and vein-like Si-Ca-rich nanostructures in the outermost and sub-outermost layers of ilmenite, respectively. In contrast, solar wind causes the formation of multilayered nanostructures surrounding the ilmenite grains. These structures are characterized by an outermost amorphous Si-rich vapor deposited layer, a middle layer rich in titanium (Ti) oxides and zero-valent iron (Fe<sup>0</sup>) nanoparticles, and an innermost layer hosting crystallographic orientation defect. The Ti oxides were identified as poorly crystallized anatase. Thermodynamic calculations indicate that the disruptive sputtering of solar wind and the reduction of hydrogen under lunar surface pressure conditions can promote ilmenite transformation into Fe<sup>0</sup> and Ti oxides; nevertheless, the pressure increase associated with melt shock can lead to a rise in the decomposition temperature of ilmenite. In other words, solar wind irradiation plays a more significant role in promoting nanoparticle (such as anatase and Fe<sup>0</sup>) formation as compared to melt shock. Thus, unlike the chemical alteration of ilmenite induced by the solar wind irradiation, melt shock mainly causes physical changes in ilmenite grains.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641799","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}
Crater counting is a widely applied methodology for dating large areas of planetary surfaces, but is difficult to apply the method to constrain the durations of stratigraphic unconformities. Unconformities with exhumed craters are thought to indicate long hiatuses that can only be indirectly dated through stratigraphic relationships with other surfaces with uniform exposure ages. On Mars, sedimentary deposits with prominent unconformities with exhumed craters are found in layered deposits in the Arabia Terra region as well as Gale crater within Mount Sharp. In this work, we present a Linear Crater Counting methodology and apply it to constrain these unconformities observed in Arabia Terra and in Mount Sharp. The method applies a linear sampling domain correction to conventional two-dimensional crater size frequency distributions and Bayesian Poisson process statistics in order to constrain the likely durations of these unconformities. We found that unconformities in Arabia Terra were on the order of 0.1–1 Gyr in length and that the unconformity preserved at Mount Sharp is at least 0.2 Gyr in length given estimates of the ages of the host craters. Hiatuses of these lengths constrain the age of the overlying deposits to be Late Hesperian or Amazonian in age. Two utility plots are also provided, along with the derivation, for researchers to apply this method to dating arbitrary geologic contacts on Mars and to adapt it to other bodies.
{"title":"Constraining the Duration and Ages of Stratigraphic Unconformities on Mars Using Exhumed Craters","authors":"A. M. Annex, K. W. Lewis","doi":"10.1029/2023JE008073","DOIUrl":"https://doi.org/10.1029/2023JE008073","url":null,"abstract":"<p>Crater counting is a widely applied methodology for dating large areas of planetary surfaces, but is difficult to apply the method to constrain the durations of stratigraphic unconformities. Unconformities with exhumed craters are thought to indicate long hiatuses that can only be indirectly dated through stratigraphic relationships with other surfaces with uniform exposure ages. On Mars, sedimentary deposits with prominent unconformities with exhumed craters are found in layered deposits in the Arabia Terra region as well as Gale crater within Mount Sharp. In this work, we present a Linear Crater Counting methodology and apply it to constrain these unconformities observed in Arabia Terra and in Mount Sharp. The method applies a linear sampling domain correction to conventional two-dimensional crater size frequency distributions and Bayesian Poisson process statistics in order to constrain the likely durations of these unconformities. We found that unconformities in Arabia Terra were on the order of 0.1–1 Gyr in length and that the unconformity preserved at Mount Sharp is at least 0.2 Gyr in length given estimates of the ages of the host craters. Hiatuses of these lengths constrain the age of the overlying deposits to be Late Hesperian or Amazonian in age. Two utility plots are also provided, along with the derivation, for researchers to apply this method to dating arbitrary geologic contacts on Mars and to adapt it to other bodies.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642002","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}
L. H. Lark, C. Huber, E. M. Parmentier, J. W. Head
The terrestrial planetary bodies display a wide variety of surface expressions and histories of volcanic and tectonic, and magnetic activity, even those planets with apparently similar dominant modes of heat transport (e.g., conductive on Mercury, the Moon, and Mars). Each body also experienced differentiation in its earliest evolution, which may have led to density-stabilized layering in its mantle and a heterogenous distribution of heat-producing elements (HPE). We explore the hypothesis that mantle structure exerts an important control on the occurrence and timing of geological processes such as volcanism and tectonism. We numerically investigate the behavior of an idealized model of a planetary body where HPE are assumed to be sequestered in a stabilized layer at the top or bottom of the mantle. We find that the mantle structure alters the patterns of heat flow at the boundaries of major heat reservoirs: The mantle and core. This modulates the way in which heat production influences geological processes. In the model, the mantle structure is a dominant control on the relative timing of fundamental processes such as volcanism, magnetic field generation, and expansion/contraction, the record of which may be observable on planetary body surfaces. We suggest that Mercury exhibits characteristics of shallow sequestration of HPE and that Mars exhibits characteristics of deep sequestration.
{"title":"Planetary Interior Configuration Control on Thermal Evolution and Geological History","authors":"L. H. Lark, C. Huber, E. M. Parmentier, J. W. Head","doi":"10.1029/2024JE008361","DOIUrl":"https://doi.org/10.1029/2024JE008361","url":null,"abstract":"<p>The terrestrial planetary bodies display a wide variety of surface expressions and histories of volcanic and tectonic, and magnetic activity, even those planets with apparently similar dominant modes of heat transport (e.g., conductive on Mercury, the Moon, and Mars). Each body also experienced differentiation in its earliest evolution, which may have led to density-stabilized layering in its mantle and a heterogenous distribution of heat-producing elements (HPE). We explore the hypothesis that mantle structure exerts an important control on the occurrence and timing of geological processes such as volcanism and tectonism. We numerically investigate the behavior of an idealized model of a planetary body where HPE are assumed to be sequestered in a stabilized layer at the top or bottom of the mantle. We find that the mantle structure alters the patterns of heat flow at the boundaries of major heat reservoirs: The mantle and core. This modulates the way in which heat production influences geological processes. In the model, the mantle structure is a dominant control on the relative timing of fundamental processes such as volcanism, magnetic field generation, and expansion/contraction, the record of which may be observable on planetary body surfaces. We suggest that Mercury exhibits characteristics of shallow sequestration of HPE and that Mars exhibits characteristics of deep sequestration.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641866","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}
J. A. McFadden, M. S. Thompson, L. P. Keller, R. Christoffersen, R. V. Morris, C. Shearer, The ANGSA Science Team
Apollo 17 core sample 73001/2 was recently made available to researchers for analysis using state-of-the-art techniques in the framework of a modern understanding of lunar surface processes. In this work, we employ transmission electron microscopic analysis to observe the mineralogy, microstructural, and chemical characteristics of space weathering and solar energetic particle (SEP) track distribution in soil grains in the <20 μm size fraction in core sample 73002. The modal mineralogy and stratigraphic space weathered grain abundance suggests that a geologically recent mixing event affected the top 3 cm of 73002. Surface exposure age distributions derived from SEP tracks demonstrate that individual regolith grains rarely reside on the surface for longer than ∼4 million years. The abundance of surface exposed monomineralic fragments with respect to depth correlates well with bulk measurements of space weathered soils using other techniques, such as ferromagnetic resonance. Exposure age distributions suggest the presence of two unique in situ reworking zones spanning the top 8 cm of the core and median exposure ages decrease with increasing depth for both reworking zones, albeit at different rates. These rates were compared to reworking models and suggest a relationship between median exposure age and reworking rate with respect to depth. Applications of modern transmission electron microscopy to core sample 73001/2 have proven useful in understanding lunar regolith evolution both within the context of the Apollo 17 field site and more broadly via in situ reworking.
{"title":"Analyzing the Mineralogy and Space Weathering Characteristics of the Finest Fraction in Apollo Core Sample 73002","authors":"J. A. McFadden, M. S. Thompson, L. P. Keller, R. Christoffersen, R. V. Morris, C. Shearer, The ANGSA Science Team","doi":"10.1029/2024JE008528","DOIUrl":"https://doi.org/10.1029/2024JE008528","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Apollo 17 core sample 73001/2 was recently made available to researchers for analysis using state-of-the-art techniques in the framework of a modern understanding of lunar surface processes. In this work, we employ transmission electron microscopic analysis to observe the mineralogy, microstructural, and chemical characteristics of space weathering and solar energetic particle (SEP) track distribution in soil grains in the <20 μm size fraction in core sample 73002. The modal mineralogy and stratigraphic space weathered grain abundance suggests that a geologically recent mixing event affected the top 3 cm of 73002. Surface exposure age distributions derived from SEP tracks demonstrate that individual regolith grains rarely reside on the surface for longer than ∼4 million years. The abundance of surface exposed monomineralic fragments with respect to depth correlates well with bulk measurements of space weathered soils using other techniques, such as ferromagnetic resonance. Exposure age distributions suggest the presence of two unique in situ reworking zones spanning the top 8 cm of the core and median exposure ages decrease with increasing depth for both reworking zones, albeit at different rates. These rates were compared to reworking models and suggest a relationship between median exposure age and reworking rate with respect to depth. Applications of modern transmission electron microscopy to core sample 73001/2 have proven useful in understanding lunar regolith evolution both within the context of the Apollo 17 field site and more broadly via in situ reworking.</p>\u0000 </section>\u0000 </div>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008528","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641423","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}
A. P. Broz, B. Horgan, H. Kalucha, J. R. Johnson, C. Royer, E. Dehouck, L. Mandon, E. L. Cardarelli, B. Garczynski, J. H. Haber, K. C. Benison, E. Ives, K. M. Stack, N. Mangold, T. Bosak, J. I. Simon, P. Gasda, E. Clave, B. S. Kathir, M. Zawaski, R. Barnes, S. Siljeström, N. Randazzo, J. M. Madariaga, K. Farley, J. Maki, L. Kah, W. Rapin, L. L. Kivrak, A. J. Williams, E. Hausrath, J. I. Núñez, F. Gómez, A. Steele, T. Fouchet, J. F. Bell, R. C. Wiens
The Mars 2020 Perseverance rover discovered fine-grained clastic sedimentary rocks in the “Hogwallow Flats” member of the “Shenandoah” formation at Jezero crater, Mars. The Hogwallow Flats member shows evidence of multiple phases of diagenesis including Fe/Mg-sulfate-rich (20–30 wt. %) outcrop transitioning downward into red-purple-gray mottled outcrop, Fe/Mg clay minerals and oxides, putative concretions, occasional Ca sulfate-filled fractures, and variable redox state over small (cm) spatial scales. This work uses Mastcam-Z and SuperCam instrument data to characterize and interpret the sedimentary facies, mineralogy and diagenetic features of the Hogwallow Flats member. The lateral continuity of bedrock similar in tone and morphology to Hogwallow Flats that occurs over several km within the western Jezero sedimentary fan suggests widespread deposition in a lacustrine or alluvial floodplain setting. Following deposition, sediments interacted with multiple fluids of variable redox state and salinity under habitable conditions. Three drilled sample cores were collected from this interval of the Shenandoah formation as part of the Mars Sample Return campaign. These samples have very high potential to preserve organic compounds and biosignatures. Drill cores may partially include dark-toned mottled outcrop that lies directly below light-toned, sulfate-cemented outcrop. This facies may represent some of the least oxidized material observed at this interval of the Shenandoah formation. This work reconstructs the diagenetic history of the Hogwallow Flats member and discusses implications for biosignature preservation in rock samples for possible return to Earth.
{"title":"Diagenetic History and Biosignature Preservation Potential of Fine-Grained Rocks at Hogwallow Flats, Jezero Crater, Mars","authors":"A. P. Broz, B. Horgan, H. Kalucha, J. R. Johnson, C. Royer, E. Dehouck, L. Mandon, E. L. Cardarelli, B. Garczynski, J. H. Haber, K. C. Benison, E. Ives, K. M. Stack, N. Mangold, T. Bosak, J. I. Simon, P. Gasda, E. Clave, B. S. Kathir, M. Zawaski, R. Barnes, S. Siljeström, N. Randazzo, J. M. Madariaga, K. Farley, J. Maki, L. Kah, W. Rapin, L. L. Kivrak, A. J. Williams, E. Hausrath, J. I. Núñez, F. Gómez, A. Steele, T. Fouchet, J. F. Bell, R. C. Wiens","doi":"10.1029/2024JE008520","DOIUrl":"https://doi.org/10.1029/2024JE008520","url":null,"abstract":"<p>The Mars 2020 <i>Perseverance</i> rover discovered fine-grained clastic sedimentary rocks in the “Hogwallow Flats” member of the “Shenandoah” formation at Jezero crater, Mars. The Hogwallow Flats member shows evidence of multiple phases of diagenesis including Fe/Mg-sulfate-rich (20–30 wt. %) outcrop transitioning downward into red-purple-gray mottled outcrop, Fe/Mg clay minerals and oxides, putative concretions, occasional Ca sulfate-filled fractures, and variable redox state over small (cm) spatial scales. This work uses Mastcam-Z and SuperCam instrument data to characterize and interpret the sedimentary facies, mineralogy and diagenetic features of the Hogwallow Flats member. The lateral continuity of bedrock similar in tone and morphology to Hogwallow Flats that occurs over several km within the western Jezero sedimentary fan suggests widespread deposition in a lacustrine or alluvial floodplain setting. Following deposition, sediments interacted with multiple fluids of variable redox state and salinity under habitable conditions. Three drilled sample cores were collected from this interval of the Shenandoah formation as part of the Mars Sample Return campaign. These samples have very high potential to preserve organic compounds and biosignatures. Drill cores may partially include dark-toned mottled outcrop that lies directly below light-toned, sulfate-cemented outcrop. This facies may represent some of the least oxidized material observed at this interval of the Shenandoah formation. This work reconstructs the diagenetic history of the Hogwallow Flats member and discusses implications for biosignature preservation in rock samples for possible return to Earth.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008520","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641518","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}
Fengshou Zhang, Wenzhi Zhao, Mengke An, Xianda Shen, Jizhou Tang, Luanxiao Zhao, Hai Liu, Derek Elsworth, Hehua Zhu, Manchao He
The projected evolutionary history of the Moon and observed occurrence of moonquakes suggest that brittle faulting is present in the shallow lunar crust. The main component of the lunar crust, plagioclase, shows velocity-strengthening behavior in the range of crustal temperatures. Chang'e 5 samples of lunar regolith show a mineral composition almost identical to basaltic bedrock. We measured the friction-stability characteristics of dry synthetic gouges representative of basaltic faults assumed to be present in the lunar crust. Frictional strengths are ∼0.7 and exhibit an overall velocity-strengthening response but transition to velocity-weakening at intermediate temperatures (∼200–300°C) and stresses (∼25–100 MPa). Bounding temperature profiles representative of the lunar crust suggest that moonquakes are feasible in the lunar crust. The rheological heterogeneity of mineral fragments in basalt is a potential cause of unstable sliding on faults with the related steady-state stress drop close to the minimum of the estimated dynamic stress drop. This suggests that some events with small stress drops are associated with the instability of mature basalt faults. However, observations of shallow moonquakes with high stress drop but merely moderate magnitude suggest that high degrees of healing on immature faults, small seismic nucleation lengths, or the failure of intact crust are present. We emphasize that moonquakes may arise from stress transfer and accumulation due to processes such as cooling contraction.
{"title":"Shallow Moonquake Mechanisms Illuminated by Rheologic Characteristics of Basaltic Gouges","authors":"Fengshou Zhang, Wenzhi Zhao, Mengke An, Xianda Shen, Jizhou Tang, Luanxiao Zhao, Hai Liu, Derek Elsworth, Hehua Zhu, Manchao He","doi":"10.1029/2024JE008370","DOIUrl":"https://doi.org/10.1029/2024JE008370","url":null,"abstract":"<p>The projected evolutionary history of the Moon and observed occurrence of moonquakes suggest that brittle faulting is present in the shallow lunar crust. The main component of the lunar crust, plagioclase, shows velocity-strengthening behavior in the range of crustal temperatures. Chang'e 5 samples of lunar regolith show a mineral composition almost identical to basaltic bedrock. We measured the friction-stability characteristics of dry synthetic gouges representative of basaltic faults assumed to be present in the lunar crust. Frictional strengths are ∼0.7 and exhibit an overall velocity-strengthening response but transition to velocity-weakening at intermediate temperatures (∼200–300°C) and stresses (∼25–100 MPa). Bounding temperature profiles representative of the lunar crust suggest that moonquakes are feasible in the lunar crust. The rheological heterogeneity of mineral fragments in basalt is a potential cause of unstable sliding on faults with the related steady-state stress drop close to the minimum of the estimated dynamic stress drop. This suggests that some events with small stress drops are associated with the instability of mature basalt faults. However, observations of shallow moonquakes with high stress drop but merely moderate magnitude suggest that high degrees of healing on immature faults, small seismic nucleation lengths, or the failure of intact crust are present. We emphasize that moonquakes may arise from stress transfer and accumulation due to processes such as cooling contraction.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641424","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}
<p>Abundant geomorphological and geochemical evidence of liquid water on the surface of early Mars during the late Noachian and early Hesperian periods needs to be reconciled with a fainter young Sun. While a dense <span></span><math> <semantics> <mrow> <msub> <mrow> <mi>C</mi> <mi>O</mi> </mrow> <mn>2</mn> </msub> </mrow> <annotation> ${mathrm{C}mathrm{O}}_{2}$</annotation> </semantics></math> atmosphere and related warming mechanisms are potential solutions to the early Mars climate problem, further investigation is warranted. Here, we complete a comprehensive survey of the warming potential of all known greenhouse gases and perform detailed calculations for 15 different minor gas species under early Martian conditions. We find that of these 15 species, <span></span><math> <semantics> <mrow> <msub> <mi>H</mi> <mn>2</mn> </msub> <msub> <mi>O</mi> <mn>2</mn> </msub> </mrow> <annotation> ${mathrm{H}}_{2}{mathrm{O}}_{2}$</annotation> </semantics></math>, <span></span><math> <semantics> <mrow> <msub> <mrow> <mi>H</mi> <mi>N</mi> <mi>O</mi> </mrow> <mn>3</mn> </msub> </mrow> <annotation> ${mathrm{H}mathrm{N}mathrm{O}}_{3}$</annotation> </semantics></math>, <span></span><math> <semantics> <mrow> <msub> <mrow> <mi>N</mi> <mi>H</mi> </mrow> <mn>3</mn> </msub> </mrow> <annotation> ${mathrm{N}mathrm{H}}_{3}$</annotation> </semantics></math>, <span></span><math> <semantics> <mrow> <msub> <mrow> <mi>S</mi> <mi>O</mi> </mrow> <mn>2</mn> </msub> </mrow> <annotation> ${mathrm{S}mathrm{O}}_{2}$</annotation> </semantics></math>, and <span></span><math> <semantics> <mrow> <msub> <mrow> <msub> <mi>C</mi> <mn>2</mn> </msub> <mi>H</mi> </mrow> <
早期火星表面在诺奇纪晚期和赫斯珀纪早期存在液态水的大量地貌和地球化学证据需要与较暗的年轻太阳相协调。虽然致密的 C O 2 ${mathrm{C}mathrm{O}}_{2}$ 大气层和相关的变暖机制是解决早期火星气候问题的潜在方案,但仍需要进一步的研究。在这里,我们完成了对所有已知温室气体变暖潜力的全面调查,并对早期火星条件下 15 种不同的次要气体进行了详细计算。We find that of these 15 species, H 2 O 2 ${mathrm{H}}_{2}{mathrm{O}}_{2}$ , H N O 3 ${mathrm{H}mathrm{N}mathrm{O}}_{3}$ , N H 3 ${mathrm{N}mathrm{H}}_{3}$ , S O 2 ${mathrm{S}mathrm{O}}_{2}$ , and C 2 H 4 ${{mathrm{C}}_{mathrm{2}}mathrm{H}}_{4}$ cause significant greenhouse warming at concentrations of ∼ ${sim} $ 0.1 ppmv or greater.然而,最高效的温室气体物种也往往更容易凝结、溶解和被光解破坏。为了给未来的大气演变和光化学研究提供参考,我们在网上免费提供了升温潜能值数据库。
{"title":"Greenhouse Warming Potential of a Suite of Gas Species on Early Mars Evaluated Using a Radiative-Convective Climate Model","authors":"Jason Jorge, Robin Wordsworth, Danica Adams","doi":"10.1029/2024JE008443","DOIUrl":"https://doi.org/10.1029/2024JE008443","url":null,"abstract":"<p>Abundant geomorphological and geochemical evidence of liquid water on the surface of early Mars during the late Noachian and early Hesperian periods needs to be reconciled with a fainter young Sun. While a dense <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>C</mi>\u0000 <mi>O</mi>\u0000 </mrow>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{C}mathrm{O}}_{2}$</annotation>\u0000 </semantics></math> atmosphere and related warming mechanisms are potential solutions to the early Mars climate problem, further investigation is warranted. Here, we complete a comprehensive survey of the warming potential of all known greenhouse gases and perform detailed calculations for 15 different minor gas species under early Martian conditions. We find that of these 15 species, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>H</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{H}}_{2}{mathrm{O}}_{2}$</annotation>\u0000 </semantics></math>, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>H</mi>\u0000 <mi>N</mi>\u0000 <mi>O</mi>\u0000 </mrow>\u0000 <mn>3</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{H}mathrm{N}mathrm{O}}_{3}$</annotation>\u0000 </semantics></math>, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>N</mi>\u0000 <mi>H</mi>\u0000 </mrow>\u0000 <mn>3</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{N}mathrm{H}}_{3}$</annotation>\u0000 </semantics></math>, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>S</mi>\u0000 <mi>O</mi>\u0000 </mrow>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{S}mathrm{O}}_{2}$</annotation>\u0000 </semantics></math>, and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <msub>\u0000 <mi>C</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 <mi>H</mi>\u0000 </mrow>\u0000 <","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641483","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}
Juan David Hernández-Montenegro, Paul D. Asimow, Claude T. Herzberg
Primary magmas form by partial melting in the mantle of a terrestrial planet and represent the starting material for building its crust. The compositions of primary magmas are critical for understanding the thermal history of planetary interiors, as they can be used to estimate mantle potential temperatures (TP) and track changes in the conditions of mantle partial melting over time. Here, we introduce PRIMARSMELT, a new member of the PRIMELT software family, calibrated to estimate the composition of Martian primary magmas and their formation conditions. We applied PRIMARSMELT to a comprehensive database of basaltic compositions from Mars. Our results are consistent with their petrology, requiring olivine addition to restore fractionated compositions to their primary parents and olivine subtraction from cumulate rocks. Individual primary magma solutions provide insights into the petrogenesis of specific Martian meteorites, with implications for the near-primary nature of some primitive meteorites and the relationship between lithologies A and B in meteorite EETA 79001. Taken together, our results suggest nearly constant or potentially increasing mantle potential temperatures throughout the geological history of Mars. The average TP for young shergottite meteorites is ∼1,442 ± 40°C, similar to ambient mantle temperatures inferred from geophysical models. In contrast, older basaltic rocks record potential temperatures as low as ∼1,320 ± 48°C for igneous clasts in meteorites NWA 7034/7533. We suggest that, rather than plume-related magmatism, shergottite meteorites record ambient mantle temperatures, with the thermal evolution trend possibly resulting from inefficient heat loss, as expected for a planet in stagnant-lid mode.
{"title":"Estimating Primary Magmas From Mars With PRIMARSMELT: Implications for the Petrogenesis of Some Martian Rocks and the Thermal Evolution of Mars","authors":"Juan David Hernández-Montenegro, Paul D. Asimow, Claude T. Herzberg","doi":"10.1029/2024JE008508","DOIUrl":"https://doi.org/10.1029/2024JE008508","url":null,"abstract":"<p>Primary magmas form by partial melting in the mantle of a terrestrial planet and represent the starting material for building its crust. The compositions of primary magmas are critical for understanding the thermal history of planetary interiors, as they can be used to estimate mantle potential temperatures (<i>T</i><sub><i>P</i></sub>) and track changes in the conditions of mantle partial melting over time. Here, we introduce PRIMARSMELT, a new member of the PRIMELT software family, calibrated to estimate the composition of Martian primary magmas and their formation conditions. We applied PRIMARSMELT to a comprehensive database of basaltic compositions from Mars. Our results are consistent with their petrology, requiring olivine addition to restore fractionated compositions to their primary parents and olivine subtraction from cumulate rocks. Individual primary magma solutions provide insights into the petrogenesis of specific Martian meteorites, with implications for the near-primary nature of some primitive meteorites and the relationship between lithologies A and B in meteorite EETA 79001. Taken together, our results suggest nearly constant or potentially increasing mantle potential temperatures throughout the geological history of Mars. The average <i>T</i><sub><i>P</i></sub> for young shergottite meteorites is ∼1,442 ± 40°C, similar to ambient mantle temperatures inferred from geophysical models. In contrast, older basaltic rocks record potential temperatures as low as ∼1,320 ± 48°C for igneous clasts in meteorites NWA 7034/7533. We suggest that, rather than plume-related magmatism, shergottite meteorites record ambient mantle temperatures, with the thermal evolution trend possibly resulting from inefficient heat loss, as expected for a planet in stagnant-lid mode.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588088","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}
Hyeonhu Park, Ian Garrick-Bethell, Brandon C. Johnson, Ho Jin
The formation of lunar crustal magnetic anomalies is not well understood, and most anomalies are not associated with any obvious geologic features. To investigate further, we studied lunar craters from 100 to 400 km in diameter (totaling 305 craters) that may have demagnetized the crust. We find that the four craters Chaplygin, Keeler, Gauss, and Fermi are highly likely to have demagnetized the crust, based on our statistical methods. We modeled the magnetic source of these craters as a simple hole in a thin magnetized plate, representing the destruction of a surficial magnetized layer (Hypothesis 1). Alternatively, we also simulated the impact demagnetization of deeper-seated magnetism in the crust by shock and temperature (Hypothesis 2). Some interior magnetization remains unexplained under both hypotheses, but the destruction of a pre-existing surficial layer of magnetized material is consistent with the location of the peak in each crater's magnetic field. We also find three of the craters are inversely correlated with remotely sensed iron, further supporting our interpretation that the craters demagnetized a surficial layer. The four craters are located on magnetized ejecta deposits from the South Pole-Aitken, Orientale, and Crisium basins. Hence, these four craters further support the hypothesis that large provinces of magnetized material on the Moon arise from hot impact ejecta that cooled in a dynamo field.
{"title":"Evidence for Magnetized Basin Ejecta on the Moon From Observations and Modeling of Demagnetized Craters","authors":"Hyeonhu Park, Ian Garrick-Bethell, Brandon C. Johnson, Ho Jin","doi":"10.1029/2024JE008420","DOIUrl":"https://doi.org/10.1029/2024JE008420","url":null,"abstract":"<p>The formation of lunar crustal magnetic anomalies is not well understood, and most anomalies are not associated with any obvious geologic features. To investigate further, we studied lunar craters from 100 to 400 km in diameter (totaling 305 craters) that may have demagnetized the crust. We find that the four craters Chaplygin, Keeler, Gauss, and Fermi are highly likely to have demagnetized the crust, based on our statistical methods. We modeled the magnetic source of these craters as a simple hole in a thin magnetized plate, representing the destruction of a surficial magnetized layer (Hypothesis 1). Alternatively, we also simulated the impact demagnetization of deeper-seated magnetism in the crust by shock and temperature (Hypothesis 2). Some interior magnetization remains unexplained under both hypotheses, but the destruction of a pre-existing surficial layer of magnetized material is consistent with the location of the peak in each crater's magnetic field. We also find three of the craters are inversely correlated with remotely sensed iron, further supporting our interpretation that the craters demagnetized a surficial layer. The four craters are located on magnetized ejecta deposits from the South Pole-Aitken, Orientale, and Crisium basins. Hence, these four craters further support the hypothesis that large provinces of magnetized material on the Moon arise from hot impact ejecta that cooled in a dynamo field.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":"129 11","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JE008420","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142588158","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}