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The grain size distribution of matrix in primitive chondrites

Vaccaro, E., Wozniakiewicz, Penelope J., Franchi, I. A., Starkey, N., Russell, S. S. (2023) The grain size distribution of matrix in primitive chondrites. Meteoritics & Planetary Science, 58 (5). pp. 688-704. ISSN 1945-5100. (doi:10.1111/maps.13979) (KAR id:100823)


The matrix of primitive chondrites is composed of submicron crystals embedded in amorphous silicates. These grains are thought to be the remains of relatively unprocessed dust from the inner regions of the protoplanetary disk. The matrix of primitive meteorites is often compared to chondritic porous interplanetary dust particles (CP‐IDPs) which are believed to be of cometary origin, having accreted in the outermost regions of the solar nebula. Crystalline grains in CP‐IDPs show evidence of a size–density relationship between the silicates and sulfides suggesting that these components experienced sorting prior to accretion. Here, we investigate whether such evidence of sorting is also present in the matrix constituents of primitive chondrites. We report findings from our study of grain size distributions of discrete silicate and opaque (sulfide and metal) grains within the matrix of the primitive meteorites Acfer 094 (C2‐ung.), ALHA77307 (CO3), MIL 07687 (C3‐ung.), and QUE 99177 (CR2). Mean radii of matrix silicate grains range from 103 nm in QUE 99177 to 2018 nm in MIL 07687. The opaque grains show a wider variation, with average radii ranging from 15 nm in QUE 99177 to 219 nm in MIL07687. Our results indicate that, in contrast to CP‐IDPs, the size distribution of matrix components of these primitive meteorites cannot be explained by aerodynamic sorting that took place prior to accretion. We conclude that any evidence of sorting is likely to have been lost due to a greater variety and degree of processing experienced on these primitive chondrites than on cometary parent bodies.

Item Type: Article
DOI/Identification number: 10.1111/maps.13979
Uncontrolled keywords: Space and Planetary Science, Geophysics
Subjects: Q Science > QB Astronomy
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Funders: Science and Technology Facilities Council (
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 11 Apr 2023 13:40 UTC
Last Modified: 27 Feb 2024 12:26 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Wozniakiewicz, Penelope J..

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