Press Release: Antarctica split wins UK visit
An ancient secret under the icy white surface of Antarcticahas been revealed by a University of Sydney academic. Dr DietmarMüller, of the School of Geosciences, has written of the ground-breakingdiscovery in the latest edition of the prestigious Nature magazine.
“We have shown that the Antarctic continent was actuallytwo tectonic plates rather than one, in the recent geological past,” DrMüller said. The discovery, backed up by data collected on tworecent Antarctic expeditions with an internationalteam, solves a mystery which has long plagued geologists.
“In order to understand the dynamics of the Earth throughgeological time periods, we need to restore the positions of all tectonicplates, which divide the Earth's surface. Before, we always had alot of trouble carrying out these reconstructions because there were misfitswe couldn’t explain, particularly between the north and south islands ofNew Zealand."
“The North Island is part of the Australian plate andthe South Island is part of the Pacific plate and there’s been some 1000km of horizontal motion between them. The missing piece of the puzzlewas firstly to find out whether Antarctica was one or two plates, and secondly,determining how the two Antarcticas may have moved relative to each otherover millions of years."
Crucial to the discovery were marine geophysical datawhich involved mapping the magnetic field and imaging the topography androcks below the sea floor. Samples were taken from remote parts ofthe southern ocean north of the Ross Sea/Antarctica.
“One of the most exciting things we found was somethinglike a small ocean basin north of the Ross Sea. It is about 200 km wide and was formed when east and west Antarctica movedapart from each other between 43 and 26 million years ago. Duringthis time, molten rock spewed out of a huge fracture, or rift, coolingand then solidifying to form new ocean floor."
Dr Müller said being on the cruise and making thesediscoveries, one felt a bit like the early explorers discovering new lands. This area was one of the last frontiers, and has never been surveyed systematicallybefore."
The new plate tectonicmodel will also help scientists to better understand the uplift historyof the Transantarctic Mountains, which linethe ancient boundary between East and West Antarctica.
This project is partially funded by an International ResearcherExchange Scheme/Australian Research Council (IREX-ARC)grant. Dr Müller, who has been with the University of Sydneyfor six years, headed the Australian component of the team, which includedtwo 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