Details of Award
NERC Reference : NE/J018031/2
The violent making of the Earth - exploring the birth and infancy of a terrestrial planet using isotope geochemistry
Fellowship Award
- Fellow:
- Professor M Willbold, The University of Manchester, Earth Atmospheric and Env Sciences
- Grant held at:
- The University of Manchester, Earth Atmospheric and Env Sciences
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Environmental Risks and Hazards
- Natural Resource Management
- Global Change
- Science Topics:
- Earth Resources
- Planetary Surfaces & Geology
- Volcanic Processes
- Mantle & Core Processes
- 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.
- NERC Reference:
- NE/J018031/2
- Grant Stage:
- Completed
- Scheme:
- Advanced Fellow (FEC)
- Grant Status:
- Closed
- Programme:
- Advanced Fellow
This fellowship award has a total value of £431,343
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Estate Costs | DI - Staff | DA - Other Directly Allocated | DI - T&S |
|---|---|---|---|---|---|
| £55,860 | £123,284 | £49,816 | £187,768 | £4,044 | £10,576 |
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