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Planetary Science Workshop - How big and how many accretionary CM chondrite parent bodies were there?

12 July 2024 - 24 January 2025
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Event type:
Workshop, Hybrid
Organised by:
Geological Society Events, Online Training, Planetary
Hybrid In person at Burlington House and Virtual via Zoom
Event status:

Join us for this hybrid workshop aiming to tackle the unknown questions surrounding the CM chondrite parent bodies, led by Dr Martin Suttle of the Open University.

The workshop will be primarily in person, based within the Council Room of the Geological Society of London, with remote participation available. It will be composed of two non-consecutive meeting days: 12 July 2024 and 24 January 2025


The overall aims of the workshop are to act as a catalyst for UK-based collaboration in early solar system research, to progress our collective understanding of the large-scale structure of carbonaceous chondrite planetesimals, and to generate one or more focused peer-reviewed publications to be published in the Journal of the Geological Society of London.


The initial meet-up will act as the definition phase, in which the selected team (~20 researchers) will identify which of these key unknowns will form the focus of this collaboration and how these research questions can be addressed. This may involve splitting the group into sub-teams, each focused on distinct methods or subject areas. 

After the definition meeting, the research team will have a six-month gap during which the agreed work plans will be implemented (data collected and models built and refined etc.). The workshop will meet again for the discussion phase in which results will be shared, discussed and a plan agreed for the structure and content of the resulting scientific publications.

Application process

Potential applicants are asked to provide an anonymised statement of interest in the workshop via email to [email protected] by the closing date listed below. This statement of interest should answer the two questions given below, and your response should be no longer than 800 words:  
  1. How would you approach answering the research question: How big and how many accretionary CM chondrite parent bodies were there? You should outline what analytical techniques, numerical models, astronomical data or otherwise you would employ to provide quantitative constraints on at least one aspect (size or number of bodies) of this question. 
  2. What expertise could you contribute to this research team? 
Applications will be assessed blind by the workshop and GSL Science team, based solely on the responses provided. A long list of applicants will be invited to then supply an up-to-date CV with their skills and experience and confirm whether attendance is likely to be in-person or remote, if successful, so that the workshop team can build a collaborative team with complementary skills across career stages. We anticipate that at least 50% of the workshop team will be constituted of early-career researchers.


Applications for this workshop are open until 10 April 2024. A first sift of anonymised applications will be conducted during the w/c 8 April, where long-listed applicants will be asked to provide a CV for shortlisting purposes. We anticipate that final notifications will be made during the w/c 22 April 2024.

Workshop dates: 12 July 2024 & 24 January 2025.


The Mighei-like (CM) chondrites are the most abundant group of hydrated meteorites, representing approximately 25% of the carbonaceous chondrite (CC) class and approximately 0.9 % of all meteorites. Currently, >730 meteorites are classified as CM chondrites, giving a combined mass of >200 kg (The Meteoritical Bulletin, 2021). Numerous main-belt C-type asteroids show plausible spectroscopic links to the CM chondrites. Furthermore, CM chondrite and CM-like material is found abundantly as xenolithic clasts within other meteorite groups and occurs as a major component of the micrometeorite flux reaching Earth today. Research interest in the CM chondrites reflects their importance as a key component in our inventory of primitive outer solar system materials and as potential sources of water and organic matter which could have been delivered in large quantities to the surfaces of inner solar system terrestrial planets via impact events. Thus, the disruption and delivery of CM chondrite materials could have played a role in the astrobiological development of the early earth.

Petrographic and isotopic analysis of the CM chondrites reveals extensive parent body alteration. This demonstrates that the CM chondrites were geologically active bodies in their own right. Their secondary, hydrated mineralogy records a prolonged episode of hydrothermal alteration, operating at high water-to-rock ratios and modest temperatures. Many CM meteorites are also overprinted by a post-hydration thermal metamorphic event. Textural, crystallographic, and noble gas data suggest repeated low-intensity impact events affected the CM chondrites. Such events may have driven the post-hydration metamorphic heating. 

A final defining feature of the CM chondrite group is their highly brecciated textures. At the millimetre-scale, CM chondrite meteorites are composed of multiple interlocking endolithic clasts of CM chondrite material. These clasts reflect the diversity of the CM chondrite group, recording similar starting materials affected to different degrees by a protracted aqueous alteration event. The lithic clasts are held together by a weakly cemented fine-grained cataclastic matrix, itself composed of CM chondrite “debris”. These observations suggest the CM parent body, or at least one member of the CM chondrite group suffered a large-scale impact event, which catastrophically disrupted the parent body and produced numerous smaller secondary asteroids (rubble-pile bodies) as well as abundant fine-grained cosmic dust. Thus, the original accretionary CM chondrite parent body may no longer exist.

Research focus:

The microanalysis of CM meteorites (and CM-like micrometeorites) has led to significant progress in our understanding of the CM chondrite group, with particular attention directed towards their accretionary properties and parent body alteration history. By contrast, the larger-scale properties of the group, including the number of first-generation accretionary parent bodies, as well as their size and the internal structure remain poorly constrained. This Geological Society of London (GSL) planetary workshop aims to bring together researchers from across the UK (and further afield) who are interested in addressing these key unknowns. Through collaborative research using a mixture of sample analysis, numerical modelling and/or experimentation we intend to provide new quantitative constraints on the number and large-scale structure of the CM chondrite parent body (or bodies).

Geolsoc Contact

Conference Office

The Geological Society
Burlington House