What can trigger destabilizing of Atlantic passive margins?

• Applicant: Dr. Marzieh Baes, Ph.D.
• Subject Area: Geophysics
• Term: from 2019 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432168024

Despite continued efforts to understand subduction initiation processes it is still enigmatic how, where and when new subduction zones form. Some localities such as intra-oceanic transform faults/fracture zones, extinct mid-oceanic ridges and passive margins have been proposed as likely sites where new subduction zones are likely to begin. Geological observations confirm subduction initiation along some of the proposed locations. However, lack of Cenozoic examples makes subduction initiation along passive margins more controversial, even though the concept continues to be widely promulgated. The broad acceptance of passive margins as favourable site for trench formation comes from the key role that they play in Wilson cycle, which explains the repeated opening and closing of ocean basins in geological time. The conversion of a passive margin into an active one is vital in the closing phase of the Wilson cycle. Most previous modelling studies have not succeeded in simulating conversion of an old passive margin into a subduction zone with realistic parameters. Here we aim to contribute to progress on this important geo-scientific problem by addressing the following questions:- What are the conditions under which an old oceanic lithosphere adjacent to a passive continental margin can spontaneously collapse and begin to subduct?- If spontaneous subduction initiation is impossible, can mantle flow associated with past and present subduction zones convert a passive continental margin into a subduction zone? - Given our answers to the first two questions, are any modern passive margins likely to convert into subduction zones in the near future?We will answer these questions by using sophisticated 3d numerical models. The aim is to construct models with realistic parameters and assumptions. We believe that answering the above questions will be a big step forward in understanding how subduction zones might begin along old passive margins, which is one of the most ambiguous issues in geosciences.

• DFG Programme: Research Grants
• International Connection: Switzerland, USA
• Co-Investigators: Professorin Dr. Andrea Hampel; Professor Dr. Stephan V. Sobolev, Ph.D.
• Cooperation Partners: Professor Dr. Taras Gerya; Professor Dr. Robert J. Stern