DOI: 10.1038/ngeo2937
论文题名: A post-accretionary lull in large impacts on early Mars
作者: Bottke W.F. ; Andrews-Hanna J.C.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2017
卷: 10, 期: 5 起始页码: 344
结束页码: 348
语种: 英语
Scopus关键词: accretion
; asteroid
; crustal thickness
; gravity
; Mars
; Martian atmosphere
; Moon
; solar system
英文摘要: The early impact bombardment of Mars has been linked to the bombardment history of the inner Solar System as a whole. However, the timing and number of basin-forming impacts on Mars are poorly constrained. The Borealis basin - thought to be the largest and oldest known Martian impact basin - forms the crustal dichotomy between the northern lowlands and southern highlands. Four unambiguous large basins post-dating Borealis have been identified, but as many as 32 additional basins larger than 1,000 km in diameter have been proposed. Here we use gravity and topography analyses to show that the crustal dichotomy boundary was excavated by only one later impact basin (Isidis), which probabilistically indicates that fewer than 12 large basins across the globe could post-date the boundary and pre-date the established younger basins. Moreover, the relatively pristine topography and crustal thickness at the dichotomy boundary indicates that younger basins should be similarly well preserved. This suggests that the post-Borealis large basin population is limited to only the four known younger basins, with estimated ages between 3.8 and 4.1 Gyr ago (Ga). We present geochemical arguments that Borealis dates to near 4.5 Ga. Combined with Monte Carlo simulations, we argue that, instead of a gradually declining impactor flux, a lull in large basin-forming impacts occurred between about 4.1 and 4.4 Ga on Mars, separating the endgame of accretion from a putative late heavy bombardment similar to that proposed for the Moon and asteroid belt. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/105792
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: Southwest Research Institute and NASA SSERVI, Institute for the Science of Exploration Targets (ISET), Boulder, CO, United States; Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, United States
Recommended Citation:
Bottke W.F.,Andrews-Hanna J.C.. A post-accretionary lull in large impacts on early Mars[J]. Nature Geoscience,2017-01-01,10(5)