Meteorite evidence for partial differentiation and protracted accretion of planetesimals

Maurel, Clara and Bryson, James F. J and Lyons, Richard J. and Ball, Matthew R. and Chopdekar, Rajesh V. and Scholl, Andreas and Ciesla, Fred J. and Bottke, William F. and Weiss, Benjamin P. (2020) Meteorite evidence for partial differentiation and protracted accretion of planetesimals. Science Advances, 6 (30). eaba1303. ISSN 2375-2548 DOI https://doi.org/10.1126/sciadv.aba1303

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Official URL: https://doi.org/10.1126/sciadv.aba1303

Abstract

Modern meteorite classification schemes assume that no single planetary body could be source of both unmelted (chondritic) and melted (achondritic) meteorites. This dichotomy is a natural outcome of formation models assuming that planetesimal accretion occurred nearly instantaneously. However, it has recently been proposed that the accretion of many planetesimals lasted over ≳1 million years (Ma). This could have resulted in partially differentiated internal structures, with individual bodies containing iron cores, achondritic silicate mantles, and chondritic crusts. This proposal can be tested by searching for a meteorite group containing evidence for these three layers. We combine synchrotron paleomagnetic analyses with thermal, impact, and collisional evolution models to show that the parent body of the enigmatic IIE iron meteorites was such a partially differentiated planetesimal. This implies that some chondrites and achondrites simultaneously coexisted on the same planetesimal, indicating that accretion was protracted and that apparently undifferentiated asteroids may contain melted interiors.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
12 - PhD
Journal or Publication Title: Science Advances
Volume: 6
Page Range: eaba1303
Identification Number: https://doi.org/10.1126/sciadv.aba1303
Depositing User: Sarah Humbert
Date Deposited: 09 Sep 2020 16:15
Last Modified: 09 Sep 2020 16:15
URI: http://eprints.esc.cam.ac.uk/id/eprint/4872

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