Seismic imaging of the Macquarie Ridge Complex: A search for incipient subduction
Subduction initiation is a crucial step in the global subduction cycle, but it remains one of the unresolved challenges of plate tectonics. Nearly half of all active subduction zones initiated during the Cenozoic (last 65 million years) which underlines the importance of this process in driving the evolution of the Earth’s surface, including the formation of oceans, continental accretion, rifting, subduction and plate reorganisation. Yet, we still do not have a basic understanding of how subduction zones nucleate, and how we transition from an incipient subduction setting to one in which subduction is self-sustaining. One of the primary reasons for this state of affairs is that we lack high quality data which are capable of constraining structure and processes in the crust and upper mantle where subduction initiation is thought to be occurring.
The goal of this project is to shed new light on the process of subduction initiation by carrying out a large seismic imaging experiment on and around Macquarie Island, which sits above the Macquarie Ridge Complex (MRC) in the southwest Pacific. Although originally thought to be part of the divergent mid-ocean ridge system, the MRC in now known to be a manifestation of the transpressive forces that arise from the relative motion between the Australian and Pacific plates. East- directed incipient subduction is thought to occur near the northern and southern ends of the MRC, but it is unclear what is happening near the central region where Macquarie Island is located.
https://eos.org/features/deploying-a-submarine-seismic-observatory-in-the-furious-fifties
https://www.antarctica.gov.au/news/2021/shaking-up-earthquake-science-on-macquarie-island/
https://cosmosmagazine.com/earth/earth-sciences/seismometers-update-sea-floor-macquarie-ridge/
Collaborators: T. Winder, H. Tkalcic, C. Eakin, M. Coffin, J. Stock
Grant: NERC Standard G100006