气候变化领域集成服务门户(CCPortal): New implications for the origin of the IAB main group iron meteorites and the isotopic evolution of the noncarbonaceous (NC) reservoir

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DOI	10.1016/j.epsl.2020.116248
	New implications for the origin of the IAB main group iron meteorites and the isotopic evolution of the noncarbonaceous (NC) reservoir
	Hilton C.D.; Walker R.J.
发表日期	2020
ISSN	0012821X
卷号	540
英文摘要	The origin of the IAB main group (MG) iron meteorites is explored through consideration of 182W isotopic compositions, thermal modeling of 26Al decay, and mass independent (nucleosynthetic) Mo isotopic compositions of planetesimals formed in the noncarbonaceous (NC) protosolar isotopic reservoir. A refined 182W model age for the meteorites Campo del Cielo, Canyon Diablo, and Nantan suggests that the IAB-MG parent body underwent some form of metal-silicate segregation as early as 5.3 ± 0.4 Myr after calcium-aluminum rich inclusion (CAI) formation or as late as 13.8 ± 1.4 Myr after CAI formation. If melting of the IAB-MG occurred prior to 7 Myr after CAI formation, it was likely driven by 26Al decay for a parent body radius >40 km. Otherwise, additional heat from impact is required for melting metal this late in Solar System history. If melting was partially or wholly the result of internal heating, a thermal model of 26Al decay heat production constrains the accretion age of the IAB-MG parent body to ∼1.7 ± 0.4 Myr after CAI formation. If melting was, instead, dominantly caused by impact heating, thermal modeling suggests the parent body accreted more than 2 Myr after CAI formation. Comparison of Mo mass independent isotopic compositions of the IAB-MG to other NC bodies with constrained accretion ages suggests that the Mo isotopic composition of the NC reservoir changed with time, and that the IAB-MG parent body accreted between 2 to 3 Myr after CAI formation, thus requiring an origin by impact. The relationship between nucleosynthetic Mo isotopic compositions and accretion ages of planetesimals from the NC reservoir suggests that isotopic heterogeneity developed from either addition of s-process material to, or removal of coupled r-/p-process material from the NC reservoir. © 2020 Elsevier B.V.
关键词	Hf-W chronometry IAB main group iron meteorites noncarbonaceous reservoir
英文关键词	Iron; Isotopes; Melting; Meteorites; Nucleosynthesis; Silicates; Thermoanalysis; Decay heat; Impact heating; Internal heating; Iron meteorites; Isotopic composition; Metal silicates; Parent bodies; Thermal model; Molybdenum; aluminum; calcium; iron meteorite; isotopic composition; molybdenum; parent body; trace element
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/202647
作者单位	Department of Geology, University of Maryland, College Park, MD 20742, United States
推荐引用方式 GB/T 7714	Hilton C.D.,Walker R.J.. New implications for the origin of the IAB main group iron meteorites and the isotopic evolution of the noncarbonaceous (NC) reservoir[J],2020,540.
APA	Hilton C.D.,&Walker R.J..(2020).New implications for the origin of the IAB main group iron meteorites and the isotopic evolution of the noncarbonaceous (NC) reservoir.Earth and Planetary Science Letters,540.
MLA	Hilton C.D.,et al."New implications for the origin of the IAB main group iron meteorites and the isotopic evolution of the noncarbonaceous (NC) reservoir".Earth and Planetary Science Letters 540(2020).