Details of Award
NERC Reference : NE/T007192/1
NSFGEO-NERC: Quantifying evolution of magmatism and serpentinisation during the onset of seafloor spreading
Grant Award
- Principal Investigator:
- Dr G G Bayrakci, National Oceanography Centre, Science and Technology
- Grant held at:
- National Oceanography Centre, Science and Technology
- Science Area:
- Earth
- Overall Classification:
- Panel A
- ENRIs:
- Global Change
- Natural Resource Management
- Science Topics:
- Tectonic Processes
- Volcanic Processes
- Abstract:
- Over periods of hundreds of millions of years, Earth's surface is recycled via the fragmentation of continents to form new oceans and elsewhere the sinking of oceanic plates into the mantle beneath. The breakup of continents involves progressive stretching and thinning prior to final breakup and the formation of new oceanic crust from molten rock that rises from below, flanked by continental margins comprised of thinned continental crust. There is a range of continental margin types, varying from those where the underlying mantle starts to melt very early in the process and very large volumes are added to the crust, to those "magma-poor" margins where there is little evidence for such melting until the very end of the process. At these magma-poor margins, which are common globally, it has been found that the crust can thin to nothing and mantle rocks can be exposed at the seabed, where they react with seawater in a process called serpentinisation. This serpentinisation plays an important role in exchange of chemicals between the Earth's interior and the ocean, and may be particularly intense around geological faults. While the final stages of thinning of the continental crust have been studied extensively over the past three decades, the transition from exposing mantle at the seabed through to forming new oceanic crust by the eruption of molten rock has been less well studied. Even designing such a study can be challenging because it is often unclear how wide this transition is. Also, because such mantle exposure has also been found in the middle of the oceans, this transition may be more complicated than often assumed. Our project will use a novel combination of geophysical techniques to study this final stage of continental breakup at a magma-poor continental margin southwest of the UK. There, crust that seems from all available data to be "normal" oceanic crust lies within about 150 km of crust confirmed by drilling to be continental. A region of serpentinised mantle, now overlain by up to around 1 km of mud, lies in between. For the first time in such a location, we will use electromagnetic waves, generated from a towed source, to measure the electrical resistivity of the crust and serpentinised mantle. Electromagnetic waves are strongly attenuated by seawater, so the source must be powerful and must be towed close to the seabed. We will use a combination of towed sensors, that are most sensitive to structures just below the seabed, and seabed detectors that can measure tiny fluctuations in electrical and magnetic fields at distances of up to tens of kilometres from our source, and thus allow us to probe deeper. We will also use some of the same seabed receivers to detect sound waves travelling through the crust from a source towed close to the ship, and to detect lower-frequency electromagnetic waves that are generated by natural sources and penetrate deeper into the Earth. The data that we collect will allow us, via the use of powerful computer programmes, to construct models of the variation of both sound speed and electrical resistivity in the crust and in the upper few tens of kilometres of the mantle beneath. These parameters provide a powerful combination because they are sensitive in different ways to the nature of the rocks. The electrical resistivity is particularly sensitive to the presence of water, and also of a mineral called magnetite that can be formed during the process of serpentinisation. The sound velocity is less sensitive to the presence of water but can be more sensitive to variations in the minerals present. From our models, we expect to be able to distinguish the continental crust and mantle, the oceanic crust and mantle, and the nature of the materials in between. We will then link these observations to computer models of the physical and chemical processes occurring as continents break apart. Thus we will find out how the formation of new oceanic crust actually starts.
- Period of Award:
- 1 Jan 2023 - 31 Dec 2025
- Value:
- £127,234 Split Award
Authorised funds only
- NERC Reference:
- NE/T007192/1
- Grant Stage:
- Awaiting Event/Action
- Scheme:
- Standard Grant FEC
- Grant Status:
- Active
- Programme:
- Standard Grant
This grant award has a total value of £127,234
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Estate Costs | DI - Staff | DI - T&S |
|---|---|---|---|---|
| £6,199 | £44,492 | £9,396 | £64,503 | £2,642 |
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