当前位置: X-MOL 学术Astron. J. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
A New Martian Crater Chronology: Implications for Jezero Crater
The Astronomical Journal ( IF 5.3 ) Pub Date : 2021-03-15 , DOI: 10.3847/1538-3881/abe417
Simone Marchi

Crater chronologies are a fundamental tool to assess the relative and absolute ages of planetary surfaces when direct radiometric dating is not available. Martian crater chronologies are derived from lunar crater spatial densities on terrains with known radiometric ages, and thus they critically depend on the Moon-to-Mars extrapolation. This extrapolation requires knowledge of the time evolution of the impact flux, including contributions from various impactor populations, factors that are not trivially connected to the dynamical evolution of the early Solar System. In this paper, we will present a new Martian crater chronology based on current dynamical models, and consider the main sources of uncertainties (e.g., impactor size–frequency distribution; dynamical models with late and early instabilities, etc.). The resulting “envelope” of Martian crater chronologies significantly differs from previous chronologies. The new Martian crater chronology is discussed using two interesting applications: Jezero crater’s dark terrain (relevant to the NASA Mars 2020 mission) and the southern heavily cratered highlands. Our results indicate that Jezero’s dark terrain may have formed ∼3.1 Ga, i.e., up to 0.5 Gyr older than previously thought. In addition, available crater chronologies (including our own) overestimate the number of craters larger than 150 km on the southern highlands, suggesting either that large craters have been efficiently erased over Martian history or that dynamical models need further refinement. Further, our chronology constrains the age of Isidis basin to be 4.05–4.2 Ga and that of the Borealis basin to be 4.35–4.40 Ga; these are predictions that can be tested with future sample and return missions.



中文翻译:

一个新的火星陨石坑年表:对杰泽罗陨石坑的影响

当直接辐射测年不可用时,陨石坑年表是评估行星表面相对和绝对年龄的基本工具。火星陨石坑年表是从具有已知辐射年龄的地形上的月球陨石坑空间密度得出的,因此它们严重依赖于月球到火星的外推。这种外推需要了解撞击通量的时间演变,包括来自各种撞击物种群的贡献,这些因素与早期太阳系的动力学演变密切相关。在本文中,我们将基于当前的动力学模型提出一个新的火星陨石坑年表,并考虑不确定性的主要来源(例如,撞击器大小-频率分布;具有晚期和早期不稳定性的动力学模型等)。由此产生的火星陨石坑年表的“信封”与以前的年表明显不同。使用两个有趣的应用程序讨论了新的火星陨石坑年表:杰泽罗陨石坑的黑暗地形(与 NASA 火星 2020 任务相关)和南部布满陨石坑的高地。我们的结果表明 Jezero 的黑暗地形可能已经形成了 ∼3.1 Ga,即比以前认为的早了 0.5 Gyr。此外,现有的陨石坑年表(包括我们自己的)高估了南部高地大于 150 公里的陨石坑数量,这表明大型陨石坑在火星历史上已经被有效地抹去,或者动力学模型需要进一步完善。此外,我们的年代学将 Isidis 盆地的年龄限制在 4.05-4.2 Ga,而 Borealis 盆地的年龄限制在 4.35-4.40 Ga;

更新日期:2021-03-15
down
wechat
bug