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基于有限元分析的月球撞击坑初始形态对月表退化作用机制研究*

穆希瑶1,2, 胡才博1,2,†, 曾兴国3, 石耀霖1,2   

  1. 1.地球系统数值模拟与应用全国重点实验室,中国科学院大学地球与行星科学学院,北京 101408;
    2.中国科学院计算地球动力学重点实验室,北京 100049;
    3.中国科学院国家天文台,北京 100101
  • 收稿日期:2026-01-16 修回日期:2026-04-07
  • 通讯作者: E-mail:hucb@ucas.ac.cn
  • 基金资助:
    *国家自然科学基金面上项目(42374116),国家重点研究计划项目(No. 2023YFF0804300, 2023YFF0804301)和中央高校基本科研业务费专项资金(E2ET0413X2)资助

Mechanisms of initial crater morphology impacting lunar surface degradation: A finite element modeling study

MU Xiyao1,2, HU Caibo1,2, ZENG Xingguo3, SHI Yaolin1,2   

  1. 1. National Key Laboratory of Earth System Numerical Modeling and Application, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 101408;
    2. The Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049;
    3. The National Astronomical Observatories of the Chinese Academy of Sciences, Beijing 100101
  • Received:2026-01-16 Revised:2026-04-07

摘要: 月球表面缺乏大气和水蚀作用,是撞击坑演化研究的理想场所。基于地形扩散理论,本研究构建一维轴对称理想模型与1.5 m高分辨率数字高程模型约束的二维模型,分析初始几何参数对撞击坑形貌退化的动力学控制机制。以直径800 m撞击坑为例,建立水平坑底、尖锐坑缘及宽缓坑缘三种剖面,量化3 Ga演化周期内形变特征:水平坑底模型沉降量最大值达88.7 m,尖锐坑缘外扩最快,宽缓坑缘退化最慢。二维模拟揭示其经历边缘钝化、物质迁移与坑底堆积过程,最大撞击坑3 Ga后坑深减少50 m。模型维度对比显示,一维与二维模型在前200 Myr形态参数一致,200 Myr后受横向扩散主导的剥蚀-堆积耦合机制影响,二维模型坑深衰减更剧烈。证实直径<200 m撞击坑在3 Ga后完全退化为低起伏地貌,导致撞击坑尺寸-频率分布定年法(CSFD)在古老月面应用时存在计数遗漏风险。本研究通过多维度模型与真实地形验证,为完善月表撞击坑年代学框架及优化月面工程选址提供定量依据。

关键词: 月球撞击坑, 月貌退化, 有限元模拟, 撞击坑定年, 高性能数值模拟

Abstract: The unique environmental features of the lunar surface, characterized by the absence of atmosphere and aqueous erosion, provide an ideal setting for studying crater evolution. Based on topographic diffusion theory, this study constructs 1D axisymmetric ideal models and 2D models constrained by real topography to systematically clarify the dynamic control mechanisms of initial geometric parameters on crater morphological degradation. By establishing 800-meter-diameter crater profiles with three typical initial morphologies: flat crater floor, sharp crater rim, and gently sloped crater rim, we quantitatively characterize their morphometric decay over a 3-billion-year evolutionary cycle. The flat-floor model exhibits maximum cumulative floor subsidence of 88.7 meters, the sharp-rim model shows the highest rim expansion rate, while the gently-sloped-rim model maintains optimal morphological stability. Two-dimensional simulations using a 1.5-meter-resolution digital elevation model (DEM) reveal characteristic processes including rim rounding, mass wasting, and floor deposition, with representative craters displaying up to 50-meter depth reduction after 3 billion years. Comparative model dimensionality analysis demonstrates strong consistency in morphometric parameters between 1D and 2D models during the initial 200 million years. Beyond this period, transverse diffusion-dominated erosion-deposition coupling mechanisms result in more significant crater depth reduction in two-dimensional models compared to their one-dimensional models. Impact craters with diameters below 200 meters completely degrade into low-relief terrain after 3 billion years, introducing omission risks in crater size-frequency distribution (CSFD) chronology for ancient lunar terrains. Through multidimensional modeling and real-terrain validation, this research establishes novel dynamic constraints for refining lunar crater chronological frameworks and optimizing engineering site selection.

Key words: lunar crater, lunar landscape degradation, finite element simulation, crater chronology, high-performance numerical simulation

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