The Vibration-Isolated Television (VIT) camera frame is suspended above the moonpool. The camera follows the drill string down to do various tasks such as survey the bottom for the best drill site and to view the condition of the hole or the re-entry cone.
Credit: Toshitsugu Yamazaki, Geological Survey of Japan
QUEENSLAND: Research into a chain of submarine volcanoes in the Pacific Ocean will lay the groundwork for scientists to reconstruct the geography of the Earth as it was millions of years ago, according to the results of a two-month expedition.
The Louisville Seamount Trail of volcanoes are thought to have been created up to 85 million years ago, as the Pacific oceanic plate passed over a ‘hotspot’ - a plume of material originating from a region deep within the mantle - according to David Buchs from The Australian National University in Canberra, who took part in the study.
“We obtained samples from different levels of the volcanoes, and this might provide key insights into their magmatic evolution. This will shed light on the dynamic processes in the Earth's mantle,” said Bruchs. “The study of these sediments will give insights into oceanographic and climatic change in the southern hemisphere 80 to 60 million years ago.”
Are hotspots really fixed in time?
Hotspots are normally regarded as fixed in relation to the moving plates. Scientists have used them as reference frames to trace the movement of the crustal plates, at rates of up to 100 mm a year, through geologic time.
Plate tectonics resulted in the break-up of ancient supercontinents, such as the huge southern landmass Gondwana, comprising Australia, Antarctica, South America, India and Africa.
“However, recent research revealed that the hotspot that created the Hawaiian-Emperor chain of volcanoes (containing over 80 undersea volcanoes and stretching over 5,800 km) to the north of the Louisville Seamount Trail might not have been stationary, but had moved about 15 degrees southward between 80 million and 50 million years ago,” said University of Queensland geochronologist Benjamin Cohen.
As part of the research crew on board the vessel JOIDES Resolution, Cohen added, “This has raised questions over whether these two Pacific plate hotspots can be used as fixed frames of reference.”
A moving frame of reference
Technicians on the research expedition drilled cores up to 522 m deep, into five Louisville volcanoes stretching over 4,300 km. The operation was performed in water depths of between 1,200 and 2,000 m. The team recovered more than 800 m of core material, comprising volcanic and sedimentary rocks.
The scientists will now begin analysing the material, which should, “tell us the ages of the Louisville volcanoes and the latitude at which they formed”, said Cohen.
“We will compare this information with the present hotspot location to see if the Louisville plume is fixed in the mantle or if it moves, as the Hawaiian hotspot seems to do.” One possibility is that the two hotspots have moved in concert, and could act as a moving frame of reference.
