气候变化领域集成服务门户(CCPortal): Evidence for early asteroidal collisions prior to 4.15 Ga from basaltic eucrite phosphate U

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DOI	10.1016/j.epsl.2020.116497
	Evidence for early asteroidal collisions prior to 4.15 Ga from basaltic eucrite phosphate U–Pb chronology
	Koike M.; Sano Y.; Takahata N.; Iizuka T.; Ono H.; Mikouchi T.
发表日期	2020
ISSN	0012821X
卷号	549
英文摘要	The late heavy bombardment (LHB) hypothesis, wherein the terrestrial planets are thought to have suffered intense collisions ca. 3.9 billion years ago, is under debate. Coupled with new dynamical calculations, re-examination of geochronological data seem to support an earlier solar system instability and a smooth monotonic decline in impacts, as opposed to a “cataclysm.” To better understand this collisional history, records from the asteroidal meteorites are required. Here, we report a uranium–lead (U–Pb) chronological dataset for eucrite meteorites thought to originate from the asteroid 4 Vesta; this dataset indicates to a continuous history of collisions prior to 4.15 Ga. Our 207Pb⁎/206Pb⁎ model ages of apatite [Ca5(PO4)3(F,Cl,OH)] and merrillite [Ca9NaMg(PO4)7] from three brecciated basaltic eucrites—Juvinas (4150.3 ± 11.6 million years ago (Ma); merrillite only), Camel Donga (disturbed around 4570–4370 Ma), and Stannern (4143.0 ± 12.5 Ma)—record multiple thermal metamorphic events during the period of ∼4.4–4.15 Ga. We interpret this to mean that Vesta or the vestoid cluster underwent multiple impacts and moderate high-temperature reheating during this time. The ages of ∼4.4–4.15 Ga are distinctly younger than the initial magmatic process on Vesta (>4.5 Ga) but are significantly older than a later “impact peak” based on some interpretations of 40Ar–39Ar chronologies (∼3.9–3.5 Ga). The intense collisions prior to 4.15 Ga on Vesta are at odds with the conventional LHB hypothesis but not inconsistent with the much earlier bombardment and monotonic decline scenario. Different radiometric chronologies of the asteroid likely represent the different stages of a continual collisional process. Conversely, the model 207Pb⁎/206Pb⁎ ages of apatite in the unbrecciated basaltic eucrite, Agoult, returned an age of 4524.8 ± 9.6 Ma. This may represent slow cooling from an earlier global reheating of the crust on Vesta at 4.55 Ga, as documented by other radiometric chronologies. The apatite in Juvinas recorded a coincident timing of 4516.9 ± 10.4 Ma, which could be due to either slow crustal cooling or impact. © 2020 The Author(s)
关键词	early collisional history of asteroids eucrites NanoSIMS U-Pb chronology of phosphates Vesta
英文关键词	Apatite; Asteroids; Basalt; Geochronology; Industrial heating; Meteor impacts; Meteorites; Radiometry; System stability; Collisional process; Different stages; Dynamical calculations; High temperature; Late heavy bombardment; Metamorphic events; Radiometric chronology; Terrestrial planets; Gallium compounds; apatite; asteroid; basalt; data set; eucrite; geochronology; meteorite; phosphate; uranium-lead dating
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/202705
作者单位	Earth and Planetary Systems Science Program, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima-shi, Hiroshima, 739-8526, Japan; Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-8564, Japan; Institute of Surface-Earth System Science, Tianjin University, Nankai District, Tianjin, 300072, China; Department of Earth and Planetary Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan; The University Museum, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
推荐引用方式 GB/T 7714	Koike M.,Sano Y.,Takahata N.,等. Evidence for early asteroidal collisions prior to 4.15 Ga from basaltic eucrite phosphate U–Pb chronology[J],2020,549.
APA	Koike M.,Sano Y.,Takahata N.,Iizuka T.,Ono H.,&Mikouchi T..(2020).Evidence for early asteroidal collisions prior to 4.15 Ga from basaltic eucrite phosphate U–Pb chronology.Earth and Planetary Science Letters,549.
MLA	Koike M.,et al."Evidence for early asteroidal collisions prior to 4.15 Ga from basaltic eucrite phosphate U–Pb chronology".Earth and Planetary Science Letters 549(2020).