The violent making of the Earth - exploring the birth and infancy of a terrestrial planet using isotope geochemistry
Lead Research Organisation:
Imperial College London
Department Name: Earth Science and Engineering
Abstract
This project aims to estimate the chemical composition of the Earth, which will contribute to our understanding of how it was formed. Knowing the chemical composition of the Earth is a fundamental parameter to almost every model in natural science, such as climate, atmospheric, oceanographic or solid Earth research. When estimating the composition of the Earth, scientists are facing a dilemma. We only have access to the very top part of the solid Earth, also called crust, which makes up only 0.5% of its mass. The remaining 99.5% are represented by the Earth's mantle and core and are beyond our reach, often buried more than 100km below the surface. Estimating the chemical composition of the entire Earth is therefore a complex and daunting task, fraught with large uncertainties, but essential to questions such as the Earth's contents of precious metals and how the key ingredients to life, particularly carbon and water, were delivered to our planet.
The Earth grew by collisions with its neighbouring planetary bodies some 4.6 billion years ago. The energies involved in these violent impacts were sufficient to melt the entire growing planet causing dense molten iron to sink to the centre and to form the Earth's core. Together with the iron, this process also stripped all precious metals, like gold and platinum, from the mantle leaving it devoid of these elements. After about 100 million years, these planetary collisions ceased and gave way to low-energy impacts of smaller asteroids. It has been suggested that this late asteroid shower, also called 'late veneer', not only delivered most of the ingredients essential for life, but also replenished the precious metal content of the mantle.
Some of the asteroids escaped incorporation into planets and have been circling the Sun unharmed for nearly 4.6 billion years. They therefore represent remnants of the building blocks that formed the Earth. Fragments of such asteroids are still falling to Earth as meteorites. They hold important clues as to what the bulk composition of the Earth was, before it separated into a core, mantle, and crust.
Over the past 40 years, the view persisted that the Earth has, on average, a chemical composition similar to that of meteorites. However, recent research showed that the rocks on Earth show a relative enrichment in the isotope 142-neodymium compared to these extraterrestrial rocks. It is therefore possible, that the Earth also has a completely different chemical composition. If true, our current models for the formation and evolution of the Earth have to be fundamentally revised.
Here, I will follow a different and novel approach of exploring this question: If one would know the composition of the crust, core, and mantle, one could simply 're-constitute' them into the composition of the whole Earth. Rocks of the crust are accessible and we know their composition. Based on geophysical evidence we also know the size of the core and we can estimate that it consists of almost 100% iron. The vital information that is still missing, is the composition of the mantle! I have developed two new analytical methods that will allow me to answer exactly this question. I will use them to measure lavas that originated in the mantle and erupted on the seafloor. For the first time, it will be possible to estimate the composition of the mantle and to calculate the composition of the Earth. The result will tell me, what the composition of the Earth's building blocks was and, ultimately, allow me to explore how the Earth was formed. Yet, I can take these studies a step further. My measurements will also show, how the precious metal-rich 'late veneer' was stirred back into the mantle and to what degree alternative explanations, such as leaking of hot iron melt from the core into the mantle, are alternative explanations of why the precious metals are so surprisingly "abundant" today.
The Earth grew by collisions with its neighbouring planetary bodies some 4.6 billion years ago. The energies involved in these violent impacts were sufficient to melt the entire growing planet causing dense molten iron to sink to the centre and to form the Earth's core. Together with the iron, this process also stripped all precious metals, like gold and platinum, from the mantle leaving it devoid of these elements. After about 100 million years, these planetary collisions ceased and gave way to low-energy impacts of smaller asteroids. It has been suggested that this late asteroid shower, also called 'late veneer', not only delivered most of the ingredients essential for life, but also replenished the precious metal content of the mantle.
Some of the asteroids escaped incorporation into planets and have been circling the Sun unharmed for nearly 4.6 billion years. They therefore represent remnants of the building blocks that formed the Earth. Fragments of such asteroids are still falling to Earth as meteorites. They hold important clues as to what the bulk composition of the Earth was, before it separated into a core, mantle, and crust.
Over the past 40 years, the view persisted that the Earth has, on average, a chemical composition similar to that of meteorites. However, recent research showed that the rocks on Earth show a relative enrichment in the isotope 142-neodymium compared to these extraterrestrial rocks. It is therefore possible, that the Earth also has a completely different chemical composition. If true, our current models for the formation and evolution of the Earth have to be fundamentally revised.
Here, I will follow a different and novel approach of exploring this question: If one would know the composition of the crust, core, and mantle, one could simply 're-constitute' them into the composition of the whole Earth. Rocks of the crust are accessible and we know their composition. Based on geophysical evidence we also know the size of the core and we can estimate that it consists of almost 100% iron. The vital information that is still missing, is the composition of the mantle! I have developed two new analytical methods that will allow me to answer exactly this question. I will use them to measure lavas that originated in the mantle and erupted on the seafloor. For the first time, it will be possible to estimate the composition of the mantle and to calculate the composition of the Earth. The result will tell me, what the composition of the Earth's building blocks was and, ultimately, allow me to explore how the Earth was formed. Yet, I can take these studies a step further. My measurements will also show, how the precious metal-rich 'late veneer' was stirred back into the mantle and to what degree alternative explanations, such as leaking of hot iron melt from the core into the mantle, are alternative explanations of why the precious metals are so surprisingly "abundant" today.
Planned Impact
The results of this study and the new methods that are to be applied will be of interest not only to academics but also to the general public, industry, and policy makers:
1) Press/Media/Museums/Science education/Lay scientific organisations/Wider public
The massive media attention that followed the publication of my most recent research on the early geological history of the Earth in the journal 'Nature' demonstrated that my research produces results, which are of interest to the wider public. There is a general public interest in natural sciences, as shown by the large number of popular scientific journals and TV programs in the UK and worldwide. The origin of our planet is a regular theme of such productions. Yet, we still know only very little about this crucial time of Earth's history and, accordingly, new scientific results on this topic are readily embraced by the media.
I anticipate that the new scientific results of the proposed project will contribute to creating an improved public awareness of the processes that play a role in how the Earth and the planets were formed. I know that the press, TV and radio media, as well as lay science organisations are keen on disseminating this information. Therefore, important immediate beneficiaries of the project will be news channels, radio programmes, newspapers, popular scientific journals, scientific TV programs, natural history museums, geography/geology education programs in schools, and lay geologists and meteoriticists associations.
2) Commercial private sector
Industry: Nanotechnology is a fast-growing commercial sector, with an estimated 3 to 4 new products being released to the market every week. The Ce method that I recently developed, and which will be used in this project, can also be applied to the isotopic tracing of engineered CeO2 nanoparticles, based on radiogenic differences in their isotopic composition. This application will be developed in collaboration with Dr Mark Rehkämper and may be of great interest for this industry sector.
Mining companies: An immediate result of the study will be to what extent the resources of precious metals that we find today in ore deposits, are due to the addition of meteoritic material to the early Earth. As such, the outcomes of this study will be of wider interest to commercial companies dealing with the mining of precious ore resources.
3) Policy makers
With the increased concern about manmade climate change, it is essential to understand the natural response of Earth systems to rapid climate change in the past, in order to predict what might happen in the future. Such future scenarios, based on high-quality data and open scientific findings, are integral to policy decisions about climate change prevention and mitigation. One of the methods that I recently developed, and which will be used in this project, will be applied to improve palaeo-oceanographic and palaeo-climate models (in collaboration with Dr Tina van de Flierdt). This work will have an immediate impact for the climate research community and this will transmit later to policy makers.
1) Press/Media/Museums/Science education/Lay scientific organisations/Wider public
The massive media attention that followed the publication of my most recent research on the early geological history of the Earth in the journal 'Nature' demonstrated that my research produces results, which are of interest to the wider public. There is a general public interest in natural sciences, as shown by the large number of popular scientific journals and TV programs in the UK and worldwide. The origin of our planet is a regular theme of such productions. Yet, we still know only very little about this crucial time of Earth's history and, accordingly, new scientific results on this topic are readily embraced by the media.
I anticipate that the new scientific results of the proposed project will contribute to creating an improved public awareness of the processes that play a role in how the Earth and the planets were formed. I know that the press, TV and radio media, as well as lay science organisations are keen on disseminating this information. Therefore, important immediate beneficiaries of the project will be news channels, radio programmes, newspapers, popular scientific journals, scientific TV programs, natural history museums, geography/geology education programs in schools, and lay geologists and meteoriticists associations.
2) Commercial private sector
Industry: Nanotechnology is a fast-growing commercial sector, with an estimated 3 to 4 new products being released to the market every week. The Ce method that I recently developed, and which will be used in this project, can also be applied to the isotopic tracing of engineered CeO2 nanoparticles, based on radiogenic differences in their isotopic composition. This application will be developed in collaboration with Dr Mark Rehkämper and may be of great interest for this industry sector.
Mining companies: An immediate result of the study will be to what extent the resources of precious metals that we find today in ore deposits, are due to the addition of meteoritic material to the early Earth. As such, the outcomes of this study will be of wider interest to commercial companies dealing with the mining of precious ore resources.
3) Policy makers
With the increased concern about manmade climate change, it is essential to understand the natural response of Earth systems to rapid climate change in the past, in order to predict what might happen in the future. Such future scenarios, based on high-quality data and open scientific findings, are integral to policy decisions about climate change prevention and mitigation. One of the methods that I recently developed, and which will be used in this project, will be applied to improve palaeo-oceanographic and palaeo-climate models (in collaboration with Dr Tina van de Flierdt). This work will have an immediate impact for the climate research community and this will transmit later to policy makers.
Publications
Willbold, M.
(2013)
The e182W Isotope Composition of the ca. 3920 Ma Acasta Gneiss Complex
in Mineralogical Magazine
Arevalo Jr., R.
(2013)
Keynote: Mantle Composition, Structure and Distribution of Radiogenic Power: Paradigms of the Earth's Interior
in Goldschmidt Abstracts
Arevalo R
(2013)
Simplified mantle architecture and distribution of radiogenic power
in Geochemistry, Geophysics, Geosystems
Hibbert, K.
(2013)
Searching for Evidence for Mo Isotope Fractionation in the Mantle
in Mineralogical Magazine
Hibbert K.
(2013)
Mass-dependent molybdenum isotopes in mid-ocean ridge basalts: A new mantle reference
in AGU Fall Meeting Abstracts
Elliott, T.
(2014)
Plenary: The Implications of a Non-Chondritic Terrestrial Mg Isotope Composition
in Goldschmidt Abstracts
Willbold M
(2015)
Tungsten isotope composition of the Acasta Gneiss Complex
in Earth and Planetary Science Letters
Willbold, M.
(2015)
The Tungsten Isotopic Composition of the Acasta Gneiss Complex
Willbold M
(2015)
High-Precision Mass-Dependent Molybdenum Isotope Variations in Magmatic Rocks Determined by Double-Spike MC-ICP-MS
in Geostandards and Geoanalytical Research
Description | More than 4 billion years ago, the Earth was a barren planet shocked by cataclysmic impacts of giant meteors and disrupted by planetary-scale volcanic eruptions. However, contrary to the more recent geological past less than 500 million years ago, we know where little about the geological processes that operated in the Early Earth and that may have completely transformed our planet into the one we know today. A ground breaking new technique has been developed that allows the high-precision measurement of tungsten (W) isotopes in geological samples. These analyses can be used to study the processes involved in the evolution of the Early Earth. |
Exploitation Route | Media: The findings of this project so far (origin of precious metals, evolution of the Early Earth) are highly topical and the media has been very interested in them. The outcomes of this study will therefore further the interest of the general public in Earth Sciences in particular and Natural Sciences in general. Research: The outcomes of the study have opened a new venue in study early geological processes on Earth and other terrestrial planets. As such, they will help other researchers inside and outside the immediate scientific community in their research. Technology: The methods and outcomes of this study may be used to understand how natural resources formed in the geological past. |
Sectors | Education Environment Culture Heritage Museums and Collections |
Description | The findings of this study help to address the question of the origin of precious metals in the Earth's crust and mantel. This is a highly popular topic and has been picked up by the media. The PI has given several interviews to news reporters and TV production companies, all interested in gaining insights into the processes and theories involved. As a result, the findings of this study have been used in various magazine and news articles as well as TV productions. The PI has provided information regarding the general context as well as more specific models about the origin of precious metals based on the findings of this project (see details in 'Common Outcomes'). He has also made an appearance in a TV production by a Japanese TV channel. Apart from this, the PI has given several public lectures, delivered professional presentations at conferences/universities and is currently in the process of publishing the first outcomes of this project in high-imapct peer-reviewed journals. The results may have opened a new window into Early Earth research. Although the findings are discussed within the scientific community there is general consensus that the results are highly topical and important for our understanding of early geological processes. |
First Year Of Impact | 2013 |
Sector | Education,Culture, Heritage, Museums and Collections |
Impact Types | Cultural Policy & public services |
Description | Standard grant (NI) - Testing the 'wet versus dry' late veneer hypothesis |
Amount | £332,000 (GBP) |
Funding ID | NE/L004011/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 08/2014 |
End | 09/2017 |
Title | Mass-dependent Mo isotope analyses in geological samples |
Description | Novel chromatographic technique for the highly-efficient isolation of Mo from geological samples for high-precision isotope analyses |
Type Of Material | Technology assay or reagent |
Year Produced | 2013 |
Provided To Others? | Yes |
Impact | Kick-off of a wide range of possible future applications of this method to geological and planetary research questions. Publication of method in high-impact, peer-reviewed analytical journal (under review). |
Title | Radiogenic W isotope measurements in geological samples |
Description | Novel chromatographic technique for the highly-efficient isolation of W from geological samples for high-precision isotope analyses. |
Type Of Material | Technology assay or reagent |
Year Produced | 2013 |
Provided To Others? | Yes |
Impact | Kick-off of a wide range of possible future applications of this method to geological and planetary research questions. |
Description | Mo isotope systematics in the terrestrial mantle |
Organisation | University of Bristol |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Provided analytical data for key geological samples. Data interpretation. |
Collaborator Contribution | Provided key geological samples. Data interpretation. |
Impact | Publication of data in peer-reviewed journal. |
Start Year | 2013 |
Description | Mo isotope systematics in the terrestrial mantle |
Organisation | University of Montpellier |
Country | France |
Sector | Academic/University |
PI Contribution | Provided analytical data for key geological samples. Data interpretation. |
Collaborator Contribution | Provided key geological samples. Data interpretation. |
Impact | Publication of data in peer-reviewed journal. |
Start Year | 2013 |
Description | W isotope systematics in the Archean terrestrial crust |
Organisation | University of Bristol |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Provided analytical data for key geological samples. Data interpretation. Produced scientific output in form of peer-reviewed journal contribution. |
Collaborator Contribution | Provided key geological samples. Provided meta-data for samples. Data interpretation. |
Impact | Peer-reviewed research paper (under review). Public lectures. Scientific contribution and advise to news-paper articles and TV productions. |
Start Year | 2012 |
Description | W isotope systematics in the Archean terrestrial crust |
Organisation | University of Colorado Boulder |
Country | United States |
Sector | Academic/University |
PI Contribution | Provided analytical data for key geological samples. Data interpretation. Produced scientific output in form of peer-reviewed journal contribution. |
Collaborator Contribution | Provided key geological samples. Provided meta-data for samples. Data interpretation. |
Impact | Peer-reviewed research paper (under review). Public lectures. Scientific contribution and advise to news-paper articles and TV productions. |
Start Year | 2012 |
Description | Astronomical Society of Manchester - Public Lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Constructive discussion amongst the audience attending the session. Recognition of research carried out by the research group. Improved understanding of research carried out at the University of Manchester. |
Year(s) Of Engagement Activity | 2015 |
Description | BBC News Magazine article |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Scientific input/advise for a magazine article published on the BBC homepage on the 19/09/2013. Feedback/questions from the general public via email. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.bbc.co.uk/news/magazine-22904141 |
Description | Bath Geological Society - Guest Lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Lecture given to members of the public with general interest in Earth Sciences. Positive feedback from the members of the Society. |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.bathgeolsoc.org.uk |
Description | Feature contribution to TV programme "Cosmic Front NEXT", NHK Japan |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Contribution (filmed interview) to Japanese TV programme "Cosmic Front NEXT". To be broadcasted in December 2015. |
Year(s) Of Engagement Activity | 2015 |
URL | http://www.nhk.or.jp/space/cfn/ |
Description | Geologists' Association - Guest Lecture |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Guest lecture given to members of the public. Very positive feedback from members of the Society. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.geologistsassociation.org.uk |
Description | Guest Speaker University of Cambridge |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Guest seminar speaker at the Department of Earth Sciences, Cambridge. Positive feedback from students attending the seminar. |
Year(s) Of Engagement Activity | 2012 |
URL | http://www.esc.cam.ac.uk |
Description | Guest Speaker at ETH Zürich |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Guest speaker at departmental seminar. Positive feedback from peers and students that have attended. |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.erdw.ethz.ch/index_EN |
Description | Guest Speaker at University of Manchester |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Guest speaker at departmental seminar. Positive feedback from peers and students attending the presentation. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.seaes.manchester.ac.uk |
Description | Guest speaker at University of Bonn (Germany) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Talk engaged students in participating in my research field. Audience asked several questions. Students contacted me several days afterwards concerning questions related to the general subject area. |
Year(s) Of Engagement Activity | 2015 |
Description | Presentation IARC symposium |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Participants in your research and patient groups |
Results and Impact | University-internal symposium to further interdisciplinary research. Sparking ideas for new research proposals. |
Year(s) Of Engagement Activity | 2013 |
Description | Science Festival Event 2015 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Public outreach 'Science Festival Event' at the Manchester Museum comprising visual as well as practical examples of research carried out. Visitors to the booth were very interested in the reattach topic asking follow-up questions as well as related questions. Possibility of having attracted pupils to take up Earth Science studies. |
Year(s) Of Engagement Activity | 2015 |
URL | http://www.manchestersciencefestival.com/whatson/thehitchhikersguidetothesolarsystem |
Description | Science Uncovered Event 2015 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | Public outreach 'Science Uncovered Event' at the Manchester Museum comprising visual as well as practical examples of research carried out. Visitors to the booth were very interested in the reattach topic asking follow-up questions as well as related questions. Possibility of having attracted pupils to take up Earth Science studies. |
Year(s) Of Engagement Activity | 2015 |
URL | http://events.manchester.ac.uk/event/event:hno-id8uglqd-6ffd2a/science-uncovered-manchester |
Description | Scientific Adviser - news article (Die Zeit) |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Scientific adviser to news article published in nationwide German newspaper. Feedback from general public via email. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.zeit.de/wissen/2013-10/gold-entstehung-geowissenschaft |
Description | Scientific Adviser - news article (Tagesspiegel) |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Scientific adviser to a newspaper article published in nationwide German newspaper. Feedback from public via email. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.tagesspiegel.de/wissen/edles-metall-die-spur-des-goldes/9007574.html |
Description | Scientific Adviser BBC World 'Really Cool Stuff' - TV 360production |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Scientific advise for the production of a TV series. Increased interest in Natural Sciences. |
Year(s) Of Engagement Activity | 2013 |
URL | http://www.bbc.co.uk/mediacentre/worldwide/160513coolstuff |
Description | Scientific Adviser Nova (PBS) 'Treasures of the Earth' - TV Pioneer Productions |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Scientific advise to production of TV series (PBS); filming commences in Feb 2015 with interviews/filming at the University of Manchester taking place shortly thereafter. Furthers general interest in Natural Sciences. |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.pioneertv.com |
Description | Session organiser 2015 Goldschmidt Conference |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Constructive discussion amongst the audience attending the session. Initiation of further collaborations. International recognition of research carried out by the research group. |
Year(s) Of Engagement Activity | 2015 |
URL | http://goldschmidt.info/2015/program/programViewThemes#session20b |
Description | Session organiser Goldschmidt Conference 2013 |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Organiser of session at international research conference. Constructive discussion amongst the audience attending the session. |
Year(s) Of Engagement Activity | 2013 |
Description | Session organiser at 2015 Goldschmidt conference |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | Constructive discussion amongst the audience attending the session. Initiation of further collaborations. International recognition of research carried out by the research group. |
Year(s) Of Engagement Activity | 2015 |
URL | http://goldschmidt.info/2015/program/programViewThemes#session20b |