Scientific ocean drilling in the Australasian region: a review
Extensive scientific ocean drilling in the Australasian region for 50 years has generated public-domain geoscience knowledge on a scale that no other science program could. Predominantly continuous coring, commonly to depths of 1000 m or more below the sea bed, has revealed the nature and origin of the continental margins, the plateaus and ridges, and the deep ocean, and put them into their plate-tectonic context. Many Australian and New Zealand scientists have played important roles in the 50 two-month regional expeditions, including building the international proposals that led to them. Large International teams aboard ship exchanged ideas and often formed long-term scientific partnerships. Most are not formally marine geoscientists or marine microbiologists. Scientists from Australia and New Zealand were also involved in numerous expeditions outside this region, but this is not their story. There have been ground-breaking results addressing global questions, such as the nature and history of plate tectonics, subduction zones and island arcs, spreading centres and polymetallic ore deposits, ocean basins and ridges, and subseafloor microbiology. Without this research, relatively little would be known about the geological history of the oceans and indeed of the continents over the last ca 150 million years. The most widely researched field has been oceanographic and climate history, which depends on plate-tectonic configuration, the thermal circulation from the Equator to the poles, and the links and constraints of deep-water circulation in the oceans. The change from a generally warm globe during the existence of Gondwana to a cooling globe after Antarctica became isolated from the rest of that supercontinent at about 33 Ma, when the deep-water Antarctic Circumpolar Current developed, cutting off the warm water and leading to a complete reorganisation of oceanic currents. Microbiological studies have shown that large communities of microbes occur deep within oceanic sediments, and also where hot fluids vent from young oceanic spreading centres and submarine island arcs.
KEY POINTS
Lithospheric plate creation and destruction is outlined in the Australasian region.
The history of the isolation of Antarctica, icehouse and global current systems are summarised.
Mantle plume (hotspot) evolution is presented.
Feeder zones of hydrothermal systems and their novel biology are given.
Lithospheric plate creation and destruction is outlined in the Australasian region.
The history of the isolation of Antarctica, icehouse and global current systems are summarised.
Mantle plume (hotspot) evolution is presented.
Feeder zones of hydrothermal systems and their novel biology are given.
