A new theory to explain the formation of the mountains of Western Europe will be unveiled in Melbourne today (Wednesday).
Until now, geoscientists worked on the basis that mountain ranges such as the Alps were formed when the tectonic plates carrying Europe and Africa came into collision.
But Gideon Rosenbaum, a PhD student from Monash University, and his supervisor Gordon Lister have found that the mountains were formed when smaller, faster moving fragments of continents came into collision about 30 million years ago.
Mr Rosenbaum said the fragments were about the size of Tasmania or Corsica.
“We’ve reconstructed the movements of the tectonic plates in the Western Mediterranean, and the results have forced us to re-think all our theories on how this area was formed,” he said.
“It’s been a big surprise to the geoscience community. We were thrilled to see the complexity of tectonic movements that occurred as mountain ranges were built during a relatively short period of time.”
Mr Rosenbaum said he used a reconstruction tool (PlatyPlus) developed by Monash University computer team to develop computer-based movies showing the tectonic history of the region.
“Soon after we started putting data together, we realized that fragments of Italy, North Africa and Spain moved independently over the last 30 million years. The southern part of Italy, for instance, was originally located adjacent to the southern coast of France, a distance of 800 km from its present position”.
Mr Rosenbaum is one of sixteen young scientists presenting their discoveries to the media, public and students for the first time, at Fresh Science. He will describe his discoveries with the help of an animated movie at a media conference at the Melbourne Museum.
Photographs and a reconstruction movie of the western Mediterranean are available.
PhD student School of Geosciences, Monash University
Migration of Mediterranean Mountain Ranges
Reconstruction of the Evolution of the Alpine Belt in the Western Mediterranean Region.
We developed an animated model illustrating the formation of the western Mediterranean mountains since 30 million years ago. We demonstrate that these mountains didn’t form because of a collision between Africa and Europe, as previously thought. Rather, they resulted from movements of continental fragments (e.g. southern Italy) that were originally located near southern France and travelled across the Mediterranean Sea.
The origin of mountain ranges is commonly attributed to the movement of tectonic plates towards each other. One of the classic examples for the occurrence of such processes is the Alpine-Himalayan mountain range, which stretches for over 10,000 km, from Spain to Southeast Asia, and is considered to represent a zone of collision between continental tectonic plates. The western part of this mountain range, in the western Mediterranean region, is commonly related to the collision between Africa and Europe. Our investigation shows that this in not the case.
The study area is located between Africa and Europe, which have been slowly moving towards each other since 120 million years ago. The mountain range is divided to several segments that encircle the western Mediterranean Sea. Our research focused on the origin and the evolution of these mountain segments. This has been done by analysing geological structures at all scales, the timing and nature of volcanic activity, the magnetic properties of rocks and the seismic behaviour of the crust and upper mantle. We have used this synthesis to define constraints, in time and space, for occurrences of regional geological processes . Accordingly, we have developed a computer-based model showing the evolution of the western Mediterranean region for the last 30 million years.
Our results show the progressive development of mountain ranges in the western Mediterranean region. Mountain building processes took place in a broad zone between Africa and Europe, and were accompanied by very little motion of Africa with respect to Europe. The majority of tectonic activity involved large horizontal motions of numerous continental blocks. Some of these blocks (e.g. the rocks of Calabria in southern Italy) moved over distances of more than 800 km (!) in a right angle to the direction of the motion of Africa relative to Europe.
Our reconstruction model illustrates a fundamental flaw in the application of plate tectonics as an explanation for the evolution of mountain ranges. Mountain ranges in the western Mediterranean did not form as a result of collision between Africa and Europe. Rather, the mountains evolved during complex tectonic interactions that included horizontal movements of subduction zones (areas where tectonic plates plunge beneath each other), opening of small seas, motions of small continental blocks and final incorporation of these blocks into the mountain range.
Address: School of Geosciences, Monash University School of Geosciences, Monash University PO Box 28E, Melbourne, 3800 VIC