Details of Award
NERC Reference : NE/J006068/1
FEC Recovery for Co-Chief Scientists Duties for Prof Damon A.H. Teagle and Petrologist Dr Michelle Harris; IODP Expedition 335 Superfast 4
Grant Award
- Principal Investigator:
- Professor DAH Teagle, University of Southampton, Sch of Ocean and Earth Science
- Grant held at:
- University of Southampton, Sch of Ocean and Earth Science
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Environmental Risks and Hazards
- Global Change
- Natural Resource Management
- Science Topics:
- Earth Resources
- Hydrogeology
- Mantle & Core Processes
- Tectonic Processes
- Volcanic Processes
- Abstract:
- The mid-ocean ridges form a chain of mountains in the oceans that circuit the Earth like seams on a baseball. These ridges are the constructive plate boundaries where new ocean crust is formed by plate tectonic spreading. This is the major process by which the Earth releases its internal heat, and ~60% of the Earth's surface was formed in the past 180 million years. Because magma is erupted onto and intruded into the ocean crust at ~1200 deg C, seawater that percolates into the crust becomes vigorously heated, commonly resulting in submarine geysers known as black smokers that disgorge >350 deg C, sulfide-rich fluids. There is a very close relationship between magma and hydrothermal "hot water" circulation. Because the ocean ridges are beneath >2000 m of water many of the processes related to their formation remain poorly understood. Scientists using submersibles can observe only the most recently erupted lavas. Geophysicists can make measurements of the ocean crust using seismic velocities (the speed that waves travel through rocks), but their results must be calibrated against actual rocks to be understood. Sampling the sub-surface of the ocean crust requires deep drilling and the recovery of basement rock cores has been a major goal of scientific ocean drilling since the 1960s. Ancient oceanic rocks preserved on land, known as ophiolites, suggest that the ocean crust is made of three basic layers: erupted lavas, commonly with pillowed shapes, that overly vertical intrusions known as sheeted dikes, which overly, coarse-grained gabbroic rocks that are crystallized magma chambers. To date only two scientific drill holes have penetrated the completely through lavas into the dikes; ODP Holes 504B and 1256D. IODP Expeditions 309-312 returned to Hole 1256D in 2005 and deepened that hole to >1500 m, completely through the lavas, dikes, and into the dike-gabbro transition. Hole 1256D in the eastern Pacific Ocean, was drilled into crust that formed at a very fast spreading rate (>200 mm/yr), because gabbros were correctly predicted to be at their shallowest there. Although only ~20% of the global ridge axis is spreading at fast spreading rates (>80 mm/yr full rate), 60% of the current ocean basins and ~30% of the Earth's surface was formed by fast spreading. Crust formed at fast spreading rates should be relatively uniform, therefore drilling at a single location can be reasonably extrapolated to describe a significant portion of the Earth's crust. This hole is now at a depth where we will be able to sample gabbros for the first time in intact ocean crust. These rocks make up two thirds of the oceanic basement formed in ancient magma chambers. However, the volume and geometry of such magma chambers are poorly known. Also poorly known is the influence of seawater percolating down through the crust on cooling the lower crust and removing heat generated during crystallization. Other fundamental parameters such as the geological meaning of Seismic Layer 3 and the Layer 2/3 boundary, as well as the contribution of the lower oceanic crust to seafloor magnetic anomalies remain poorly understood. The cores and geophysical data recovered on IODP Expedition 335 from Hole 1256D will provide a unique resource for understanding the igneous construction of the ocean crust. By making careful descriptions linked with shipboard (and post-cruise) chemical analyses we will be able to calculate the size of magma chambers, the physical conditions of fluid-rock interactions, and calibrate remote regional seismic and magnetic geophysical measurements. This will lead a significantly improved knowledge of how the oceanic crust is constructed and ages away from the ocean ridges, and test long-standing, competing models magmatic accretion and hydrothermal cooling.
- NERC Reference:
- NE/J006068/1
- Grant Stage:
- Completed
- Scheme:
- Directed (Research Programmes)
- Grant Status:
- Closed
- Programme:
- UK IODP
This grant award has a total value of £75,708
FDAB - Financial Details (Award breakdown by headings)
| Indirect - Indirect Costs | DA - Estate Costs | DI - Staff | DA - Other Directly Allocated |
|---|---|---|---|
| £13,427 | £6,080 | £55,668 | £533 |
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