The major science areas identified (see for example the IMAGES Programme and IODP Initial Science Plan) are:
- Earth’s Surface Environmental Change, Processes and Effects
- The Deep Biosphere & Sub-Seafloor Ocean
- Solid Earth Cycles & Geodynamics
European science initiated or leads many of the fields in which ocean coring has, or will, contribute vital information. Marine coring science topics of immediate importance to Europe and having a, traditionally, strong European component include:
Ocean climate dynamics and impacts on continental climates
Elucidation of the controls on climate and climate change needs high-resolution records with a spatial distribution capable of capturing specific local responses and global transmission of climate variables. Records of past changes in oceanic thermohaline circulation, atmosphere-ocean interactions, and land-ocean climate linkages will be particularly important to climate modelling.
Arctic and Antarctic oceans: Control of climate and ocean circulation
The Arctic is particularly sensitive to global climatic change, but its climatic and biogeochemical records are virtually unknown. Freshwater transport from the Arctic is likely to have a major effect on the global thermohaline circulation in ways that we are not yet able to predict, as are the effects of sea-ice in the Arctic and Antarctic realms.
Ocean biogeochemistry and the carbon cycle
Oceanic biological carbon cycling is central to carbon budgets but neither the role of limiting micronutrients nor the feedback between ocean biogeochemistry, climate and greenhouse concentration are resolved.
Deep biosphere
The recent discovery by European scientists of the existence of a deep subsurface microbial population down to more than 500 m depths, comprising ~ 10% of the surface biomass, has major implications for biogeochemical fluxes, diagenesis and hydrocarbon generation, and the origin and evolution of life. It is also important as a potential source of organisms for biotechnology.
Gas hydrates
Ocean coring has confirmed that gas hydrates (a solid water-methane phase) found in the top few hundred metres of oceanic sediments contain about twice as much carbon as is contained in all known fossil fuels and hence are a potential economic source of hydrocarbons. The hydrates are dynamic systems fed by biological and thermogenic methane sources. Coring has revealed past catastrophic global releases of methane possibly triggered by climate change and responsible for intense, but short-lived, climatic warming and catastrophic tsunamis.
Geodynamo and the Earth’s magnetic field
High-resolution palaeomagnetic records recovered by ocean coring are providing an inter-hemispheric age control on sediments, independent of fossil evolution and stratigraphy which at very fine scale may be not globally continuous or synchronous. They also give important new information on the behaviour of the geodynamo, origin of the Earth’s magnetic field. These areas have ramifications for both surficial and solid Earth processes. Records of Earth’s magnetic field are required to unravel the relation between frequency and nature of paleointensity changes and changes in climate and biological development and deep-Earth processes, and shorter-term geodynamic cycles are linked to major natural hazards (earthquakes, tsunamis and explosive volcanic eruptions).
Ocean seismic arrays and oceanic sub-surface observatories
Developments in instrumentation and communication underpin recent and proposed installations of instruments to make long-term measurements of environmental parameters at the seafloor (e.g. Monitoring the Mid-Atlantic Ridge MOMAR). These observatories will provide critical monitoring of active processes (e.g. fluid movement below the seabed), as well as larger scale experiments such as allowing the distribution of seismometers to the maximum advantage in viewing the 3D structure of our planet.
Ocean ridge processes
Ocean ridges dominate both global magmatic budgets and hydrothermal exchanges of heat and chemical elements to the oceans. Coring will be crucial for resolving hydrothermal geochemical fluxes, the interplay between magmatic, tectonic and hydrothermal processes in the construction and evolution of oceanic crust, and the mechanisms that control the movement of the Earth’s mantle, its melting and incorporation into new lithosphere.
Seismogenic zone, subduction, mountain building and erosion
The hydrology and mechanical behaviour of the seismogenic zone above subduction zones is vital to understanding seismic hazards in an environment where 80% of the world’s damaging earthquakes (and resulting tsunamis) occur, and where a significant proportion of the global population and a major part of the global economy is at risk. The new Japanese drill ship will make this environment accessible for the first time.
Deformation of the continents: Volcanic and non-volcanic rifted margins
Continental deformation is a major, fundamental geological process. The rheology of the lower crust and upper mantle and how these determine strain partitioning in continental evolution are poorly known. As mountains are built, they are continuously eroded, and the products are deposited as sediments in deep-sea fans that are accessible only by coring. Coring the complete sedimentary record of the evolution of mountain belts available in deep sea fans, and sampling the deeper parts of continental margin extensional regimes, which contain the records of early continental break-up, will contribute enormously to understanding these first-order geological processes, including the proposed link between mountain belt uplift and global climate change.
