Plume-induced subduction initiation: Insights from the south-western margin of the Caribbean

• Applicant: Privatdozent Dr. Sascha Brune
• Subject Area: Geophysics
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405341049

Subduction zones are main components of plate tectonics and around 90% of the plate driving forces stem from the negative buoyancy of sinking lithosphere in subduction zones. However, despite their vital role, it is still enigmatic how and where subduction zones form. In most of previous modeling studies a pre-existing weakness zone in the lithosphere, which is itself the product of plate tectonics, is a key ingredient for subduction initiation. A recently proposed scenario that is independent of any pre-existing weakness zone, is plume-induced subduction initiation, which can explain the beginning of the first subduction zone without the help of plate tectonics. According to this scenario, the arrival of a buoyant plume beneath oceanic lithosphere results in the formation of several slabs surrounding a newly formed plateau. However, many key aspects of this new scenario have not been investigated yet.The most important questions are:- What is the lithosphere’s response to plateau-plume interaction and which processes control lithospheric deformation? - What is the impact of regional extension on plume-plateau interaction? - How does an existing subduction zone near the plume-lithosphere interaction affect the dynamics of subduction initiation? Does it change the pattern of lithospheric deformation? If so, what is the effect of the subduction parameters such as dip angle and subduction rate in this process? - Which parameters play key roles for the formation of a single one-sided plume-induced subduction zone (instead of formation of several slabs around the newly formed plateau)?In this project, we will answer these questions by using cutting-edge 3-d numerical models. We apply our models to the geologically most recent example of plume-induced subduction at the south-western margin of the Caribbean plate, which occurred around 100 million years ago. We believe that answering the above questions will be a big step forward in understanding subduction initiation and in resolving major outstanding issues concerning the tectonic evolution of the Caribbean region.

• DFG Programme: Research Grants
• International Connection: India, Switzerland, USA
• Co-Investigator: Professor Dr. Stephan V. Sobolev, Ph.D.
• Cooperation Partners: Professor Dr. Taras Gerya; Professor Dr. Robert J. Stern; Professor Dr. Scott Whattam