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Differentiation and magmatic history of Vesta: Constraints from HED meteorites and Dawn spacecraft data

McSween, Harry Y., Jr. and Raymond, Carol A. and Stolper, Edward M. and Mittlefehldt, David W. and Baker, Michael B. and Lunning, Nicole G. and Beck, Andrew W. and Hahn, Timothy M. (2019) Differentiation and magmatic history of Vesta: Constraints from HED meteorites and Dawn spacecraft data. Geochemistry, 79 (4). Art. No. 125526. ISSN 0009-2819. https://resolver.caltech.edu/CaltechAUTHORS:20191220-102538469

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Abstract

Quantifying the amounts of various igneous lithologies in Vesta’s crust allows the estimation of petrologic ratios that describe the asteroid’s global differentiation and subsequent magmatic history. The eucrite:diogenite (Euc:Diog) ratio measures the relative proportions of mafic and ultramafic components. The intrusive:extrusive (I:E) ratio assesses the effectiveness of magma ascent and eruption. We estimate these ratios by counting numbers and masses of eucrites, cumulate eucrites, and diogenites in the world’s meteorite collections, and by calculating their proportions as components of crustal polymict breccias (howardites) using chemical mixing diagrams and petrologic mapping of multiple thin sections. The latter two methods yield a Euc:Diog ratio of ∼2:1, although meteorite numbers and masses give slightly higher ratios. Surface lithologic maps compiled from spectra of Dawn spacecraft instruments (VIR and GRaND) yield Euc:Diog ratios that bracket estimates of Euc:Diog from the meteorites. The I:E ratios from HEDs lie between 0.5–2.1:1, due to uncertainties in identifying cumulate eucrite. Gravity mapping of Vesta by the Dawn spacecraft supports the existence of diogenite plutons in the crust. Quantifying the proportion of high-density diogenitic crust in the gravity map yields I:E ratios of 0.8-1:2:1, values which are bracketed by calculations based on HEDs. The I:E ratio for Vesta is lower than for Earth and Mars, consistent with physical modeling of asteroid-size bodies. Nevertheless, it indicates a significant role for pluton emplacement during the formation of Vesta’s crust. These results are inconsistent with simple differentiation models that produce the crust by crystallization of a global magma ocean, unless residual melts are extracted into crustal magma chambers.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.chemer.2019.07.008DOIArticle
ORCID:
AuthorORCID
Stolper, Edward M.0000-0001-8008-8804
Mittlefehldt, David W.0000-0002-5920-8987
Additional Information:© 2019 Elsevier GmbH. Received 31 May 2019, Accepted 26 July 2019, Available online 14 September 2019. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. We acknowledge J. E. C. Scully for help in producing area estimates, and Jeff Taylor and Patrick Donohue for critical reviews.
Funders:
Funding AgencyGrant Number
NASA/JPL/CaltechUNSPECIFIED
Subject Keywords:Vesta; Asteroid; HED meteorites; Dawn spacecraft; Intrusive:extrusive ratio; Eucrite:diogenite ratio
Issue or Number:4
Record Number:CaltechAUTHORS:20191220-102538469
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191220-102538469
Official Citation:Harry Y. McSween, Carol A. Raymond, Edward M. Stolper, David W. Mittlefehldt, Michael B. Baker, Nicole G. Lunning, Andrew W. Beck, Timothy M. Hahn, Differentiation and magmatic history of Vesta: Constraints from HED meteorites and Dawn spacecraft data, Geochemistry, Volume 79, Issue 4, 2019, 125526, ISSN 0009-2819, https://doi.org/10.1016/j.chemer.2019.07.008. (http://www.sciencedirect.com/science/article/pii/S0009281919300285)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100390
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Dec 2019 19:27
Last Modified:20 Dec 2019 19:27

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