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DOI	10.1016/j.epsl.2020.116667
	Billion-year exposure ages in Gale crater (Mars) indicate Mount Sharp formed before the Amazonian period
	Martin P.E.; Farley K.A.; Malespin C.A.; Mahaffy P.R.; Edgett K.S.; Gupta S.; Dietrich W.E.; Malin M.C.; Stack K.M.; Vasconcelos P.M.
发表日期	2021
ISSN	0012821X
卷号	554
英文摘要	The erosion rates and mechanisms operating on Mount Sharp in Gale crater, Mars were assessed via experiments performed by the SAM instrument to determine the cosmogenic noble gas contents of Murray mudstone formation samples Mojave 2 and Quela. Previous measurements of samples from the Aeolis Palus depression between Mount Sharp and the north rim of Gale crater indicate that scarp retreat-generated surfaces formed within the last 100 Ma. In contrast, Mojave 2 yielded exposure ages of 1,320±240 (3He), 910±420 (21Ne), and 310±60 Ma (36Ar). Quela gave a 3He age of 1,460±200 Ma; 21Ne and 36Ar from this sample could not be quantified due to isobaric interferences. The discordant and young 36Ar exposure age in Mojave 2 is likely the result of interaction with water which dissolved the chlorine-bearing host phases of this nuclide. The most probable exposure scenario is that both Mojave 2 and Quela have been at the surface for the most recent ∼1 Ga after the overlying few meters of rock were removed in a geologically rapid exhumation episode. Based on local geomorphology, scarp retreat is the most likely mechanism for the exposure at these two sites. The exposure ages measured throughout Curiosity's traverse indicate that the net removal of rock has proceeded more recently on Aeolis Palus than on the lower slopes of Mount Sharp. The implied differential erosion rate is insufficient to explain how Mount Sharp formed, even over billions of years. Instead, given that the surfaces on Mount Sharp have existed for >1 Ga, the mountain must have formed early, likely during the Hesperian. This study provides direct quantitative support for inferences based on crater counts that Mount Sharp had eroded to close to its current form before onset of the Amazonian. © 2020 Elsevier B.V.
关键词	Curiosity exposure dating geochronology geomorphology Mars
英文关键词	Erosion; Cosmogenic; Erosion rates; Exposure age; Gas content; Isobaric interferences; Measurements of; Most likely; Inert gases; crater; dating method; erosion rate; exhumation; geochronology; geomorphology; Mars; mudstone
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203213
作者单位	California Institute of Technology, Pasadena, CA, United States; Goddard Space Flight Center, Greenbelt, MD, United States; Malin Space Science Systems, San Diego, CA, United States; Imperial College London, London, United Kingdom; University of California Berkeley, Berkeley, CA, United States; Jet Propulsion Laboratory, Pasadena, CA, United States; University of Queensland, Brisbane, QD, Australia
推荐引用方式 GB/T 7714	Martin P.E.,Farley K.A.,Malespin C.A.,et al. Billion-year exposure ages in Gale crater (Mars) indicate Mount Sharp formed before the Amazonian period[J],2021,554.
APA	Martin P.E..,Farley K.A..,Malespin C.A..,Mahaffy P.R..,Edgett K.S..,...&Vasconcelos P.M..(2021).Billion-year exposure ages in Gale crater (Mars) indicate Mount Sharp formed before the Amazonian period.Earth and Planetary Science Letters,554.
MLA	Martin P.E.,et al."Billion-year exposure ages in Gale crater (Mars) indicate Mount Sharp formed before the Amazonian period".Earth and Planetary Science Letters 554(2021).