GEOSCIENCE

Marine geoscience is the study of sea-bed materials and the processes which have formed them. Geoscientists are engaged in a wide variety of applied investigations offshore, with many working in oil and gas exploration.

Geochemists provide critical information about the character of fossil fuels and the beds that have generated them, while palaeontologists study the age and character of key strata. Petroleum geologists and geophysicists search for fossil fuels using evidence such as the type, thickness, and organic content of sediments, the structural form of sedimentary basins, and possible migration paths by which oil and gas might reach suitable reservoirs in porous sedimentary beds.

Geophysicists use indirect methods such as seismic reflection profiling to map and evaluate subsurface strata, while geologists use drill samples. For seismic profiling, artificial shock waves are produced by explosives or compressed air. Geophysicists measure the time for sound waves to travel through and return from different layers of rock, and use computers to produce both cross-sections through the earth and maps of key beds. Other geophysical techniques utilise variations of the earth's magnetic and gravitational fields to interpret the nature of the underlying strata.

Mineral exploration companies search the sea for deposits of gold, tin and diamonds. Gravel and sand will soon be extracted from the sea bed in preference to mining rivers and coastal dunes. Some companies are assessing the feasibility of mining valuable metals from nodular manganese and iron concretions from the deep ocean floor.

Study of sea-bed materials using corers, sonar, submersibles, remote vehicles and other technology provides vital information to marine engineers for designing offshore or coastal structures, such as harbours, oil platforms, pipelines, and telecommunications cables. The transport of sediment is also important to coastal engineering. In examining these processes, engineers call on physical oceanographers to provide information on waves and tidal and other water currents. The erosion, transport and deposition of sediment in the coastal zone can result in eroded shorelines, the formation of beaches, and siltation of bays, all of which are important considerations in coastal management.

As a consequence of exciting developments in technology, marine geoscience is changing rapidly and offers many new frontiers and challenges. Expected areas of growth include oil and gas exploration, offshore engineering, environmental management and remote sensing technology.

The primary training required is in the physical sciences (geology, chemistry and geography), usually combined with mathematics and physics. An alternative is engineering or training in science-law. Geoscientists are employed by oil and mineral exploration companies, engineering companies, universities, environmental consulting groups, government geological surveys, and public works departments. Many have both offshore and onshore responsibilities.

Photos: (top) Deploying instruments in an operation from the purpose-built ship (below) RV Rig Seismic.