BLOG 3: Goals of the voyage
3D map of Lanceolata Seamount indicating planned route through sea floor terrain
3D map of Lanceolata Seamount
By Chris Meagher
Some of the largest mountains in Australia are below the surface of the water resting on a 5 km deep seabed. Many of these underwater mountains (or seamounts) were formed from hotspot volcanoes millions of years ago, and scientists are hoping that this voyage will provide them with vital information about how these massive edifices came into existence.
While Volcanoes most commonly form at the edges of tectonic plates, hotspot volcanoes form away from plate boundaries and are thought to occur over particularly hot areas of the semi-liquid mantle found below the Earth’s crust. Hotspot volcanoes form in chains as the tectonic plates which makeup the Earth’s crust, move over the mantle. The Hawaiian Island chain is the most famous of these; however, Australia boasts a number of its own hotspot volcano mountain chains, and the current voyage is tracing the path of the Balleny hotspot which currently resides below the Balleny Islands in Antarctica.
Underwater topography map
Scientists use underwater topography maps to determine the best sites to collect ancient volcanic rocks.
The existence of hotspots and tectonic plate theory was only agreed upon about 50 years ago so this is a relatively young branch of science, and geologists and volcanologists are hoping that the current voyage will allow them to understand more about tectonic plates and hotspot volcanoes in particular.
The seamounts are being examined in two ways on this voyage. Firstly sonar technology is used to develop detailed maps of the underwater topography (or bathymetry). The size and shape of the seamounts provide clues about their formation. Scientists also use these maps to determine the best sites to collect ancient volcanic rocks using deep-water dredge baskets which are lowered many kilometres under the water surface.
This data will help scientists piece together how the tectonic plates have been moving over the last 80 million years. It will also help them to determine the role of the Balleny hotspot in the breakup and fragmentation of the Gondwana supercontinent into present day Australia, Antarctica, India and South America.