Do oceanic subduction zone systems have multiple arc/backarc cycles?

• Applicants: Professor Dr. Kaj Hoernle; Professorin Dr. Heidrun Kopp
• Subject Area: Geophysics ; Geology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564896509

Oceanic volcanic arcs and backarcs make up a significant portion of the seafloor, representing important regions of element transfer from the earth’s interior to its surface. How arcs and backarcs initiate, evolve and eventually die and the processes that control the long-term history of arc-backarc systems remain poorly understood. The seafloor north of New Zealand hosts a sequence of remnant arc ridges and backarc basins: Norfolk Ridge, Norfolk Basin, Three Kings Ridge and South Fiji Basin. We propose a multidisciplinary study to understand the tectonic, structural, temporal, and geochemical evolution of these arc-backarc sequences. We seek to test a preliminary model that involves subduction rollback and extension, leading to three distinct cycles of arc splitting and backarc basin formation to ultimately generate the present-day Tonga-Kermadec arc and Lau-Havre Trough backarc basin system. Our study will provide unprecedented insights into mantle and crustal processes causing and accompanying subduction initiation and volcanic arc/backarc evolution and cessation.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 2520: Infrastructure area - Research Vessels
• Co-Investigator: Dr. Christian Timm