Geochemistry and petrology of howardite Miller Range 11100: A lithologically diverse piece of the Vestan regolith

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms it is akin to the fragmental howardite meteorites. The strong lithological heterogeneity across this 29 sample suggests that at least some parts of the Vestan regolith show heterogeneity on the mm-scale. 30We combine the outcomes of this study with data from NASA's Dawn mission and hypothesize on 31 possible source regions for this meteorite on the surface of Vesta. 32 33

Chondrule heritage and thermal histories from trace element and oxygen isotope analyses of chondrules and amoeboid olivine aggregates

“…; Gregory et al. ) and mesosiderites (Greenwood et al. ) or phenocrysts in pallasites and primitive achondrites (Mittlefehldt et al.…”

“…4d). Also, the CaO and Al 2 O 3 contents of type I chondrule olivine (on average 0.3 and 0.2 wt%, respectively) are generally much higher than in putative mantle olivine such as olivine clasts in howardites (Lunning et al 2015;Gregory et al 2017) and mesosiderites (Greenwood et al 2015) or phenocrysts in pallasites and primitive achondrites (Mittlefehldt et al 1998), where they rarely exceed 0.1 wt%-presumably as a result of efficient extraction of basaltic melts from their crystallization regions. Regardless of the formation environment of chondrules, nebular condensates may thus have been their immediate precursors.…”

Recycled Components in Mantle Plumes Deduced From Variations in Halogens (Cl, Br, and I), Trace Elements, and 3He/4He Along the Hawaiian‐Emperor Seamount Chain

“…Counting times for all elements (Si, Al, Cr, Fe, Mn, Mg, Ca, Na, K, Ni and Co) was 60 s, determined as the optimal configuration to obtain the best detection limits. Prior to analysis the background and sensitivity of the microprobe was determined using well‐characterized silicate, oxide, and metal standards (Gregory et al, ).…”

Mineralogy and petrology of dark clasts in the Allan Hills 76005 polymict eucrite pairing group

“…Howardites and howarditic impact melts have been most commonly found in HED breccias and meteorites and described in the literature. For example, the Pecora Escarpment (PCA) howarditic impact melts described by Beck et al (2012), the howarditic glasses and impact melts of Singerling et al (2013), the EET 92014 magnesian clast of Mittlefehldt and Lindstrom (1997), howarditic impact melt clasts from MIL 11100 (Gregory et al 2017), howarditic or polymict eucritic clasts from GRO 95633 and Malvern (Hewins and Klein 1978; Delaney et al 1983, 1984; Mittlefehldt and Lindstrom 2003), Kapoeta (Dymek et al 1976; Pun et al 1998), EET 87503 (,68 and ,69 are polymict clasts based on pyroxenes and also elevated siderophile elements from Metzler et al [1995]; Buchanan and Mittlefehldt [2003]), EET 79011 (Palme et al 1983), and Petersburg (Buchanan and Reid 1996) all are more magnesian than the main group eucrites. Even the Pomozdino and ALH 81001 eucrites are slightly more magnesian than main group eucrites, leading some to argue they have diogenitic component or are from a differentiated asteroid different from Vesta (Mittlefehldt and Lindtsrom 1997).…”