Press Release: Antarctica split wins UK visit
An ancient secret under the icy white surface of Antarctica has been revealed by a University of Sydney academic. Dr Dietmar Müller, of the School of Geosciences, has written of the ground-breaking discovery in the latest edition of the prestigious Nature magazine.
“We have shown that the Antarctic continent was actually two tectonic plates rather than one, in the recent geological past,” Dr Müller said. The discovery, backed up by data collected on two recent Antarctic expeditions with an international team, solves a mystery which has long plagued geologists.
“In order to understand the dynamics of the Earth through geological time periods, we need to restore the positions of all tectonic plates, which divide the Earth's surface. Before, we always had a lot of trouble carrying out these reconstructions because there were misfits we couldn’t explain, particularly between the north and south islands of New Zealand."
“The North Island is part of the Australian plate and the South Island is part of the Pacific plate and there’s been some 1000 km of horizontal motion between them. The missing piece of the puzzle was firstly to find out whether Antarctica was one or two plates, and secondly, determining how the two Antarcticas may have moved relative to each other over millions of years."
Crucial to the discovery were marine geophysical data which involved mapping the magnetic field and imaging the topography and rocks below the sea floor. Samples were taken from remote parts of the southern ocean north of the Ross Sea/Antarctica.
“One of the most exciting things we found was something like a small ocean basin north of the Ross Sea. It is about 200 km wide and was formed when east and west Antarctica moved apart from each other between 43 and 26 million years ago. During this time, molten rock spewed out of a huge fracture, or rift, cooling and then solidifying to form new ocean floor."
Dr Müller said being on the cruise and making these discoveries, one felt a bit like the early explorers discovering new lands. This area was one of the last frontiers, and has never been surveyed systematically before."
The new plate tectonic model will also help scientists to better understand the uplift history of the Transantarctic Mountains, which line the ancient boundary between East and West Antarctica.
This project is partially funded by an International Researcher
Exchange Scheme/Australian Research Council (IREX-ARC)
grant. Dr Müller, who has been with the University of Sydney
for six years, headed the Australian component of the team, which included
two Phd students from the university.
(If you or your library is a subscriber to NATURE, you can download the full text of the paper as html of pdf file).
ABC The Lab:
News in Science online
New findings
on Antarctica's ancient dance
Maps of Antarctica
Action at Sea
Geophysical images
Scenery of McMurdo
Computer
animation of plate motions
Author details:
1 Scripps Institution of Oceanography
La Jolla, CA 92093-0215
2 California Institute of Technology
Mail Stop 252-21
Pasadena, CA 91125
3 School of Geosciences
Building F05
The University of Sydney
NSW 2006, Australia
4 Geological Survey of Japan
1-1-3 Higashi
Tsukuba
Ibaraki 305-8567, Japan