Susanne Buiter, Geological Survey of Norway
Abstract: The geodynamic evolution of continental margins
The geodynamic evolution of continental margins
The motions of continental plates over geological times reshape Earth’s surface, forming mountains where plates converge and rifts where they move apart. This destruction and creation of continental margins tends to occur in similar locations over time, thereby leading to the closing and opening of oceans in a process commonly referred to as the Wilson Cycle. A classic example is the Wilson Cycle in the North Atlantic region where closure of the Iapetus Ocean led to continent-continent collision in the Silurian and formation of the Caledonian mountain belt. After a long period with several rifting phases, the present-day North Atlantic Ocean opened nearby the Caledonian collision zone in the early Cenozoic. In fact, most, if not all, of the present-day rifted continental margins of the Atlantic and Indian Oceans formed on former collision zones. This is probably not surprising since collision zones contain structural, compositional and thermal inheritances that would favour localisation of rifting. But how does such collisional inheritance impact continental rifted margins? In this lecture, we will review geodynamic experiments of the formation, evolution and destruction of continental plate margins. We first discuss fault interaction processes and the sensitivity of model plate margins to choices of crustal rheology and plate velocities. We then show how mountains can become rifts and rifts could become mountains. Our experiments raise the question of the level of structural complexity models need to reach for meaningful comparisons to geological and geophysical observations of continental margins.
Submitted by: S.J.H. (Susanne) Buiter | Co-authors: John Naliboff