Geology and geophysical facilities

A major theme of geological and geophysical research in Antarctica is determining how the ice sheet responded to natural climate changes in the past to reduce uncertainty in predictions of future climate and sea level change. This is information for informing Government strategy for mitigating against these risks. Find out more in the ‘Science’ tab.

Using its dynamic positioning system, RRS Sir David Attenborough will be able to hold its position accurately even during rough seas to allow for effective sampling. She will be capable of supporting and deploying a range of geological and geophysical equipment.

Sediment coring

Undisturbed sea-floor sediments can reveal the past history of the Antarctic continent. Sampled from the ocean floor or from beneath ice shelves, these sediments can be taken back to the lab for analysis to aid investigations into ice-shelf thinning and retreat, sedimentary processes and oceanic circulation.

Research teams recover sediment cores from the seafloor using a variety of methods and instruments.

RRS Sir David Attenborough will be capable of handling a 40.6m OSIL giant piston corer, which will fit in standard shipping containers and will be able to recover sediment cores from the seafloor containing detailed records going back hundreds of thousands, if not a few million, years.

OSIL Giant Piston Corer aboard R/V Kaimei. Image courtesy of JAMSTEC.

Cores can also be collected in locations underneath floating ice shelves using hot-water drilling technology, giving researchers access to the seafloor even in places where the ocean is permanently covered by ice. Collecting and analysing cores gathered from a ship and through the ice helps to provide a more complete picture of previous ice sheet behaviour.

The RRS Sir David Attenborough will also feature a 12-core Oktopus MC12/100 multi-corer. This collects 60 cm of sediment, with an undisturbed surface, which can be sampled in detail. Using this technology, researchers can study parameters such as particle size, organic carbon content, microfossil assemblages, stable isotopes, trace metal contents, biomarkers and accumulation rate.

A multi-sensor core logging scientific container can be placed on board to open directly into the ship’s wet lab. This means that non-destructive analyses of the cores can be conducted onboard the ship before they are sampled.

Oktopus Mega Multi Corer
Oktopus Mega Multi Corer packed away

Magnetometer

Towed magnetometers are frequently deployed in the ocean during geoscience research cruises and are central to many geophysical studies. They can be used to produce a map of magnetic lineations, which contain a record of the rates and directions of sea-floor spreading.

Magnetometer data is the most important type of data for reconstructing the motions of tectonic plates, and played an important role in the widespread acceptance of plate tectonic theory in the 1960s.

The RRS Sir David Attenborough will be equipped with a state-of-the-art towed Overhauser magnetometer for use on geoscience cruises.

BAS geophysicist Tom Jordan prepares a magnetometer for deployment on the RRS James Clark Ross
BAS geophysicist Tom Jordan prepares a magnetometer for deployment on the RRS James Clark Ross

Gravity meter

The gravity meter will be installed close to the centre of motion of the vessel and will operate continuously, detecting small differences in the Earth’s gravity field that indicate variations in the geology beneath the sea floor. Gravity data are typically combined with seismic and magnetic observations to determine the locations and extent of igneous intrusions or the thickness of sediment accumulations.

Seismic facilities

Seismic profiling systems are an effective way of studying the structure and composition of the sediments and rocks below the sea floor. Acoustic signals from an air gun can penetrate layers of sediment and bedrock and are reflected to varying degrees by layers of different materials. An array of sensitive hydrophones towed behind the ship picks up the reflections of the air-gun signal from the seafloor and the layers below it. This data can be used to produce a profile of the seabed rocks rather than just the surface.

RRS Sir David Attenborough will be equipped with advanced generator-injected airguns as well as air compressors to facilitate research into the geology of the seafloor.

Air gun array being deployed on the RRS James Clark Ross
Air gun array being deployed on the RRS James Clark Ross

For other geological and geophysical capabilities, please see the section on the ship’s rock drilling capability and acoustic instruments. These are primary tools used by marine geoscientists.

Records of past climate, ecosystems and physical processes are preserved in seafloor sediments and the landforms on the Antarctic continental shelf. This area is essential for understanding how ice flow dynamics and long-term interactions between ice flow dynamics and the ocean surrounding Antarctica.

Polar research ships allow researchers to collect samples and data from remote locations using state-of-the-art sonar tools and specialised drills and corers. The resulting data include detailed maps of the seafloor that can shed light on past glacial processes and climatic changes.

Sediment cores collected from the seafloor can yield accurate records of past ecosystems and the way in which large-scale oceanic currents have changed over decades to millions of years. They also contain invaluable data about past climates – the giant piston corer that can be deployed from RRS Sir David Attenborough will be able to recover sediment cores over 40m deep. This allows for high-resolution data going back roughly half a million years, or more coarse-resolution information going back as long as 2.7 million years. Reconstructing past changes to the Antarctic ice sheet and ecosystems, particularly during periods of warming, is important for predicting future responses and its contribution to future sea-level rise. The results can also be used to test current models of future changes, by examining whether models can accurately reproduce the observed record of behaviour from sediment cores.

Autonomous underwater vehicles and remotely operated vehicles allow researchers access to study sites that are too dangerous or difficult to reach for people, such as glacier calving faces and the undersides of ice shelves. These regions are key to understanding the changes taking place in the Antarctic ice sheet, which could have global climatic repercussions. These vehicles can carry high-resolution sonar system and some ROVs can also collect push cores and vibrocores.