Details of Award
NERC Reference : NE/Y002350/1
Micro-structural controls on oceanic core complex formation: IODP Exp 399 Atlantis Massif
Grant Award
- Principal Investigator:
- Dr M Harris, University of Plymouth, Sch of Geog Earth & Environ Sciences
- Grant held at:
- University of Plymouth, Sch of Geog Earth & Environ Sciences
- Science Area:
- Earth
- Marine
- Overall Classification:
- Unknown
- ENRIs:
- Biodiversity
- Environmental Risks and Hazards
- Global Change
- Natural Resource Management
- Pollution and Waste
- Science Topics:
- Tectonic Processes
- Faulting
- Mid-ocean ridges
- Ocean drilling
- Oceanic crust
- Plate tectonics
- Seafloor spreading
- Electron-Atom Scattering
- Scattering & Spectroscopy
- Chemical analysis
- Technol. for Environ. Appl.
- Abstract:
- The surface of the Earth is divided up into tectonic plates that have moved throughout Earth history and these plates are continually created and destroyed at the boundaries between plates. In the oceans, features called mid-ocean ridges create new volcanic seafloor along the boundaries between two diverging tectonic plates. These mid-ocean ridges creating a vast chain of underwater volcanoes that circle the oceans like the seams of a baseball. Whilst much of the growth of new seafloor is driven by magmatic processes at mid-ocean ridges, these regions are subjected to high stresses which deform the crust in various ways, primarily along linear features called faults. When erupted onto the seafloor, crack and faults within newly formed ocean crust allow seawater to percolate deep into the crust, where it is heated and reacts with the surrounding rocks to form new minerals. This process, called hydrothermal circulation, produces variably hot fluids rich in elements that become buoyant and exit the seafloor via vents, which host unique ecosystems. The conditions here are our closest comparison to the environments where life may have first developed. Studying the seafloor rocks therefore provides us with an unrivalled opportunity to study plate tectonic processes, the evolution of our planet, and the emergence of life on Earth. To study these mid-ocean ridges we require samples of the seafloor. One way these samples can be accessed is through scientific drilling by the International Ocean Discovery Programme (IODP), which recovers rock core samples drilled from beneath the seafloor. IODP Expedition 399 will sample the Atlantis Massif ocean core complex at 30N on the Mid-Atlantic Ridge, which forms the plate boundary between the North American and Eurasian plates. The speeds of these plates are unusually slow. Consequently, seafloor spreading along the Mid-Atlantic Ridge is accommodated by deformation rather than magmatism. Large detachment faults bring rocks from deep in the crust to the seafloor creating domal structures called oceanic core complexes. These detachment faults promotes fluid circulation, and a positive feedback develop whereby fluids react with the fault rocks creating new, but weak secondary minerals that promote further deformation. Whilst we know a link between deformation and fluid flow exists, the grain scale mechanisms responsible for this link are poorly understood. In this project we will investigate the controlling grain-scale deformation mechanisms of detachment faulting, via microstructural analyses of fault rock samples collected on Expedition 399. We predict that the deformation mechanisms will change over time due to hydrothermal activity, which produces weak, low-friction secondary minerals. We will investigate the types of secondary alteration minerals present in the detachment fault, and how those minerals influenced deformation. We also predict that deformation mechanisms will change over time due to a reduction in temperature, which changes the mechanical properties of minerals. We will therefore constrain the temperatures at which the observed deformation occurred to understand if and how deformation evolved during cooling. Microstructural analyses will be conducted at the University of Plymouth and University of Cardiff with state-of-the-art electron microscopy techniques including electron backscatter diffraction (EBSD) and electron dispersive spectroscopy (EDS). These techniques quantitatively constrain grain-scale deformation mechanisms, deformation temperatures and mineral chemistry, by measuring the crystal structure and chemistry of deformed rock samples. Our research will provide a new understanding of the processes which control the detachment faults. This is vital for understanding the relationships between deformation and hydrothermal activity at slow-spreading ridges, and the controls that those processes have on plate tectonics and hydrothermal ecosystems.
- NERC Reference:
- NE/Y002350/1
- Grant Stage:
- Awaiting Termination
- Scheme:
- Directed (RP) - NR1
- Grant Status:
- Active
- Programme:
- UK IODP Phase4
This grant award has a total value of £42,398
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Investigators | DA - Estate Costs | DI - Staff | DA - Other Directly Allocated | DI - T&S |
|---|---|---|---|---|---|---|
| £3,377 | £7,475 | £220 | £1,699 | £22,075 | £2,078 | £5,475 |
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