The origin of short-lived nuclides in the early solar system: implications for the assembly of terrestrial bodies

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences

Abstract

Short-lived isotope systems play a critical role in constraining the timescales of early solar system processes. They also potentially finger-print the stellar sources of material in the solar nebular and provide a mechanism for nebular collapse. In all these respects the constraints provided by the very short lived 26Al and 60Fe (with half-lives 0.75 and 1.5My respectively) are key. Furthermore, as major, refractory elements, these extinct isotopes once constituted an essential part of the accreting terrestrial planets and provided a significant early heat source to drive planetary differentiation. Recent work in the Fe-Ni system yield tantalising data, but highlight perennial problems in deconvolving time from initial heterogeneity when interpretting these short-lived systems. In this proposal we will explicitly address these issues by combining new high precision techniques in analysis of Fe-Ni, Al-Mg and U-Pb on same meteoritical objects (CAI and chondrules). We will thus determine the initial 60Fe and 26Al for samples absolutely dated by U-Pb and examine if this differs between meteorites groups. This will allow us to determine the magnitude of any nebular heterogeneity, assess its causes and robustly re-evaluate the chronology of the early solar system.

Publications

10 25 50
 
Description We have discovered that the short-lived nuclide, 60Fe (half-life 2.6 million years), believed by many to provide heat for planetary melting in the early solar system was not present insufficient abundances to be of significant importance. In contrast, the Ni isotopic composition of minor planets (planetesimals) represented by meteorites do show variability in their (non-radiogenic) Ni isotopic fingerprint, which must have been inherited from imperfect mixing of pre-solar material in the early solar system. We attempted to identify the type of star (the stellar source) in which the material which defines the solar system variability was derived. Our new approach identified a conventional 'type II' super nova as a potential source, different to the inferences of previous work.
We also opportunistically investigated the history of the slightly longer lived nuclide 182Hf (half-life 9million years) and its decay to 182W. We used these measurement to show a small (15 part per million) difference between ancient and modern terrestrial samples, which is entirely in keeping with the delivery of ~0.5% of the mass of the Earth as meteorites in a 'Late Veneer'. This bombardment, after formation of the Earth's core, brought with it all the currently accessible gold and precious metals currently available to humanity.
Exploitation Route Our demonstration of significant differences in bulk Ni isotopic compositions has led us and others to more closely explore the origin of material that leads to gross compositional differences in the solar system.
Our demonstration of the ability of new multi-collector inductively coupled plasma mass-spectrometers to make ~5 parts per million measurements opens up new vistas for a wide range of cosmochemical and geochemical applications.
The discovery of preservation of pre-Late Veneer material on Earth allows the mixing of Late Veneer material into the Earth's interior to be traced.
Sectors Aerospace, Defence and Marine,Education,Environment

 
Description Our findings have generated significant further research interest including ERC grant for PI, STFC grant for collaborators, post-doctoral position for PhD student of PI. There was considerable, international media interest in our findings about the Late Veneer.
First Year Of Impact 2011
Sector Education,Environment
Impact Types Cultural

 
Description ERC Advanced Grant
Amount € 3,490,000 (EUR)
Funding ID IsoNeb 321209 
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 05/2013 
End 04/2018
 
Description Collaboration with Martin Bizzarro 
Organisation University of Copenhagen
Department Centre for Star and Planet Formation
Country Denmark 
Sector Public 
PI Contribution We collaborated over high precision Ti isotopic measurements, that could be made as a logical extension of the proposed STFC work
Collaborator Contribution Provided separated Ti samples from a number of meteorites, which we analysed
Impact This lead to the Science paper by Trinquier et al already noted
Start Year 2008
 
Description Collaboration with Prof Sara Russell and Dr Erika Kurahashi 
Organisation Natural History Museum
Department Department of Mineralogy
Country United Kingdom 
Sector Public 
PI Contribution Dr Kurahashi used the Mg isotopic procedure we had established as part of this grant to try to help with her research into chondrule remelting. This work was then developed into the successful STFC grant ST/J001473/1
Collaborator Contribution Dr Kurahashi work in our laboratory for several months and in addition to exploring the work we had established herself experimented with the potential of laser ablation measurement of Mg isotopes
Impact Dr Kurahashi made several presentations at Met Soc meetings, including some work done at Bristol, but during her time with us, we had not sufficiently refined our procedures to resolve the questions she needed to answer.
Start Year 2010
 
Description Advised BBC for Wonders of Solar System 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Talked for an hour with Ben Wilson about the origin of isotopes

Formed a very minor part of information exchange to a major international TV series
Year(s) Of Engagement Activity 2010
 
Description Bath Geological Society "Violent birth of the Earth and the source of precious metals" 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact ~40 enthusiastic attendees, normally used to more geological presentation but interested about extra-terrestrial influences

n/a
Year(s) Of Engagement Activity 2012
 
Description European Association of Geochemistry Distinguished Lecturer in eastern Europe 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact I presented 4 talk in five locations Warsaw (Poland), Wroclaw (Poland), Sofia (Bulgaria) and Cluj (Romania) using the finding funded as part of this project. This trip was funded by the European Association of Geochemistry.

Significant interest generate and the profile raised of UK science in these emerging research nations
Year(s) Of Engagement Activity 2012
 
Description Evening talk to local Astronomy group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact ~1 hour talking describing the information isotopes can provide about the formation of the solar system

Members of the public were enthused
Year(s) Of Engagement Activity 2010
 
Description Media work following publication of nature article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact On publication of the Willbold et al article, our work was covered in the national and international (German, Portugese, Australian, French) press in hardcopy (notably Sun, Mirror, Mail in terms of circulation) and online. Matthias Willbold (PDRA) did many online interviews and I (Elliott PI) did a Radio 4 interview with the Material world.

Several podcast, broadcasts, online articles. Significant international impact.
Year(s) Of Engagement Activity 2011
 
Description Talks at International conferences. Between myself PI and the PDRA we gave 5 aural (including 2 keynote) talks in various international meetings on our results over the course of the project 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact We reached a wide audience on two continents in both geochemical and cosmochemical communities

n/a
Year(s) Of Engagement Activity 2009,2010,2011,2012