GEOSCIENCE

Marine geoscience is the study of sea-bed materials and the processes that have formed them. Marine geoscientists investigate a broad range of topics ranging from the origin and permanence of ocean basins to the assessment of resources on and beneath the sea floor.

Geologists work directly with marine geophysicists in studying the earth beneath the sea bed to determine the type of rocks present and their geological history. Exploration techniques include collection and analysis of samples and direct probing of the subsurface by drilling. Palaeontologists use fossils, especially microfossils, to determine the age of strata. Geochemists use the ratios of various elements' isotopes to determine the origin of certain materials and the temperature at which they formed. Sedimentologists interpret the source of ocean floor sediments and the mode of their transport and deposition. Geophysicists use indirect methods such as seismic reflection to investigate subsurface materials. Explosives or compressed air produce shock waves which penetrate the rocks below, and the time it takes sound waves to travel through and bounce off different layers of rock provides information about their nature. Other routine geophysical techniques utilise variations in magnetic and gravitational fields and heat flow patterns within the earth to interpret the nature of the underlying crust.

Petroleum geologists use all these data to assess the likelihood that fossil fuel reservoirs are present beneath the sea bed. Mineral exploration companies also search the sea floor for metal deposits. Sedimentary deposits of gold have been discovered offshore and the feasibility of mining heavy metals, such as nodular concretions of manganese, from the ocean floor is being assessed. Marine geoscientists also study the sea-bed materials of the continental shelf and coastal regions to assist marine engineers design offshore and nearby structures. The movement and distribution of sediment in the coastal zone are important areas of study that are critical to management of the coastal zone.

Marine geoscience is a field which is changing rapidly, particularly in response to innovations in technology and equipment. Australia is a participant in the Deep Sea Drilling Project, which is a world-wide program that is yielding new and exciting information, especially from the deep oceans. Relatively recent application of specialised technology has revealed that sea-bed sediments contain a remarkably complete record of environmental change.

Organisations employing marine geoscientists include various commonwealth and state government departments such as the Australian Geological Survey Organisation, industrial corporations including petroleum exploration companies, geological and engineering consultants, and academic institutions.

Photo: The research vessel Joides Resolution, the drilling ship of the international Ocean Drilling Program, which is run by a consortium of countries including Australia.