Australasian Science: Australia's authority on science since 1938

A Piece of North America Is Now in Queensland

Credit: Ruslan Olinchuk

Credit: Ruslan Olinchuk

By Adam Nordsvan, Zheng-Xiang Li & Bill Collins

Geologists have discovered rocks in northern Queensland that bear striking similarities to those found in North America, suggesting that part of northern Australia was actually part of North America 1.7 billion years ago.

The full text of this article can be purchased from Informit.

Throughout the Earth’s four-billion-year history, as continents shifted around the globe they periodically massed together to form super­continents. Most recently this occurred about 300 million years ago when the southern continents (Africa, South America, Australia and Antarctica) and India joined Eurasia and North America to form the supercontinent Pangea.

Three supercontinents existed in the past two billion years: Pangea (320–170 Ma), Rodina (900–700 Ma) and Nuna (1600–1400 Ma). In Nuna, the least-known supercontinent of the three, it has been proposed that the east coast of Australia was adjacent to either North America (Laurentia) or Siberia. Researchers around the globe are working to advance this latest frontier in supercontinent research.

Reconstructing the ancient supercontinents is not easy. Each continent consists of discrete blocks, separated from one another by sutures: zones of deformation where the blocks collided. Geologists must characterise the blocks and match them with other blocks from different continents. They also need to determine the age of the sutures in order to work out when when the blocks came together. In this way, the continents are like pieces of a global jigsaw puzzle that have to be matched together at distinct periods of time. It’s a 3D problem, plus time!

What makes the problem worse is that many of these...

The full text of this article can be purchased from Informit.