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Meteorit Planetary Scien - 2024 - Daly - Brecciation at the grain scale within the lithologies of the Winchcombe Published.pdf (7.78 MB)

Brecciation at the grain scale within the lithologies of the Winchcombe Mighei‐like carbonaceous chondrite

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posted on 2024-05-14, 10:08 authored by Luke Daly, Martin D Suttle, Martin R Lee, John Bridges, Leon Hicks, Pierre‐Etienne MC Martin, Cameron J Floyd, Laura E Jenkins, Tobias Salge, Ashley J King, Natasha V Almeida, Diane Johnson, Patrick W Trimby, Haithem Mansour, Fabian B Wadsworth, Gavyn Rollinson, Matthew J Genge, James Darling, Paul AJ Bagot, Lee F White, Natasha R Stephen, Jennifer T Mitchell, Sammy Griffin, Francesca M Willcocks, Rhian Jones, Sandra Piazolo, Joshua F Einsle, Alice Macente, Lydia J Hallis, Aine O'Brien, Paul F Schofield, Sara S Russell, Helena Bates, Caroline Smith, Ian Franchi, Lucy V Forman, Phil A Bland, David Westmoreland, Iain Anderson, Richard Taylor, Mark Montgomery, Mark Parsons, Jérémie Vasseur, Matthias van Ginneken, Penelope J Wozniakiewicz, Mark J Burchell, Daniel Hallatt, Luke S Alesbrook, Vassilia Spathis, Richard Worden, Julie Behnsen, Kate Black

The Mighei‐like carbonaceous (CM) chondrites have been altered to various extents by water–rock reactions on their parent asteroid(s). This aqueous processing has destroyed much of the primary mineralogy of these meteorites, and the degree of alteration is highly heterogeneous at both the macroscale and nanoscale. Many CM meteorites are also heavily brecciated juxtaposing clasts with different alteration histories. Here we present results from the fine‐grained team consortium study of the Winchcombe meteorite, a recent CM chondrite fall that is a breccia and contains eight discrete lithologies that span a range of petrologic subtypes (CM2.0–2.6) that are suspended in a cataclastic matrix. Coordinated multitechnique, multiscale analyses of this breccia reveal substantial heterogeneity in the extent of alteration, even in highly aqueously processed lithologies. Some lithologies exhibit the full range and can comprise nearly unaltered coarse‐grained primary components that are found directly alongside other coarse‐grained components that have experienced complete pseudomorphic replacement by secondary minerals. The preservation of the complete alteration sequence and pseudomorph textures showing tochilinite–cronstedtite intergrowths are replacing carbonates suggest that CMs may be initially more carbonate rich than previously thought. This heterogeneity in aqueous alteration extent is likely due to a combination of microscale variability in permeability and water/rock ratio generating local microenvironments as has been established previously. Nevertheless, some of the disequilibrium mineral assemblages observed, such as hydrous minerals juxtaposed with surviving phases that are typically more fluid susceptible, can only be reconciled by multiple generations of alteration, disruption, and reaccretion of the CM parent body at the grain scale.

Funding

Making Habitable Worlds: The Formation and Evolution of Moons and Planets

Science and Technology Facilities Council

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The UK Fireball Alliance - building an all-sky UK meteor observatory

Science and Technology Facilities Council

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UK leadership in extraterrestrial sample return

Science and Technology Facilities Council

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The cosmic carbon observatory

Science and Technology Facilities Council

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ST/S000348/1; ST/R00143X/1

Strategic equipment bid: Ultra high-resolution 3D and 4D X-ray imaging

Engineering and Physical Sciences Research Council

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Planetary Science at The University of Manchester

Science and Technology Facilities Council

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History

Author affiliation

College of Science & Engineering/Physics & Astronomy

Version

  • VoR (Version of Record)

Published in

Meteoritics & Planetary Science

Volume

59

Issue

5. Special Issue: The science of the Winchcombe meteorite

Pagination

1068-1100

Publisher

Wiley

issn

1086-9379

eissn

1945-5100

Copyright date

2024

Available date

2024-05-14

Language

en

Deposited by

Professor John Bridges

Deposit date

2024-05-09

Rights Retention Statement

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