The research team, including scientists from the Universities of Southampton and St Andrews in the UK, Australia's Curtin University, and the Geological Survey of Western Australia, carried out a detailed field investigation at the Murchison greenstone belt in Western Australia, home to some of the world's oldest and best-preserved remnants of the Earth's early crust.
The team found evidence suggesting that the ancient continents were formed through a process of continental growth by amalgamation of smaller landmasses, termed 'cratons', that grew through time by accretion of newly formed volcanic arcs.
The study also indicates that the ancient volcanic arcs formed on the edges of oceanic plates rather than on the present continental margins. Volcanic arcs formed on oceanic plates commonly become detached and may later collide with continental margins to form new mountain belts, such as the Andes.
Lead author Dr Nick Timms, Associate Professor in the School of Ocean and Earth Science at the University of Southampton, says:
"Our results suggest that the ancient continents formed by amalgamation of many small landmasses and were composed of different rock types to those found in modern continents, which are dominated by granite. Understanding the early continents is important, because they shaped the evolution of the Earth's atmosphere and gave rise to the first ecosystems."
The research, part-funded by the Natural Environment Research Council (NERC), is published in the journal Nature Geoscience.
