气候变化领域集成服务门户(CCPortal): Petrological evidence for the existence and disruption of a 500 km-sized differentiated planetesimal of enstatite-chondritic parentage

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DOI	10.1016/j.epsl.2020.116506
	Petrological evidence for the existence and disruption of a 500 km-sized differentiated planetesimal of enstatite-chondritic parentage
	Harries D.; Bischoff A.
发表日期	2020
ISSN	0012821X
卷号	548
英文摘要	Two samples of a unique achondritic lithology of the Almahata Sitta meteorite (MS-MU-019 and MS-MU-036) contain three coexisting pyroxene species: orthoenstatite, clinoenstatite and augite. The silicate assemblage appears to be the restite after extraction of melts of broadly basaltic and metal-sulfide composition from an enstatite chondrite protolith. Transmission electron microscopy (TEM) provides evidence that clinoenstatite within the lithology formed from earlier protoenstatite. The absence of pigeonite despite the successful nucleation of augite and the persistence of orthoenstatite during cooling suggests that the sub-solidus formation of the three coexisting pyroxenes occurred at a pressure of about 0.1 GPa. Rapid cooling at >1 K/h below 1260°C is documented by the cessation of augite equilibration, preservation of the 3-pyroxene assemblage and a low volume fraction of nanoscale orthoenstatite lamellae formed during the transformation of protoenstatite to clinoenstatite. The pressure implies a diameter of roughly 500 km of the differentiated parent body, putting petrological constraints on the size of planetesimals that may have contributed to the accretion of the terrestrial planets including Earth. The high cooling rate indicates a catastrophic disruption of this large planetesimal early in its history. The lithology studied here underlines that planetesimals which existed in the inner Solar System were more diverse than previously thought, and included potentially large differentiated bodies with very FeO-poor, enstatite-dominated mantles. Remains of these bodies are poorly represented in meteorite collections, which points to efficient accretion in the inner Solar System or to removal and little re-distribution of material into the present-day asteroid belt. © 2020
关键词	accretion differentiation enstatite achondrite petrology pyroxenes transmission electron microscopy
英文关键词	Cooling; High resolution transmission electron microscopy; Iron oxides; Lithology; Meteorites; Silicate minerals; Solar system; Sulfur compounds; High cooling rates; Metal sulfides; Orthoenstatite; Parent bodies; Protoenstatite; Rapid cooling; Re-distribution; Terrestrial planets; Gasoline; achondrite; enstatite chondrite; lithology; petrology; planetesimal; protolith; silicate; Sitta
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/202632
作者单位	Institute für Geowissenschaften, Friedrich-Schiller-Universität Jena, Carl-Zeiss-Promenade 10, Jena, 07745, Germany; Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, Münster, 48149, Germany
推荐引用方式 GB/T 7714	Harries D.,Bischoff A.. Petrological evidence for the existence and disruption of a 500 km-sized differentiated planetesimal of enstatite-chondritic parentage[J],2020,548.
APA	Harries D.,&Bischoff A..(2020).Petrological evidence for the existence and disruption of a 500 km-sized differentiated planetesimal of enstatite-chondritic parentage.Earth and Planetary Science Letters,548.
MLA	Harries D.,et al."Petrological evidence for the existence and disruption of a 500 km-sized differentiated planetesimal of enstatite-chondritic parentage".Earth and Planetary Science Letters 548(2020).