Budget of a complete section of oceanic lithosphere at the Vema fracture zone

• Applicant: Professor Andreas Stracke, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 564896262

The project "VEMANTLE" will recover rocks from several stratigraphic profiles that expose the entire oceanic lithosphere along the Vema fracture zone (VTZ) in the Atlantic. Despite previous studies of rocks from the VTZ, no assessment of the compositional variation and total compositional budget of the entire section of ocean lithosphere, and the temporal variability of the parameters and processes of oceanic lithosphere formation exist. Detailed mapping and ROV sampling of several profiles through the entire oceanic lithosphere at variable distance from the active ridge axis (i.e., increasing lithospheric age) will allow assessing the structural relationships and will recover representative rock samples from all lithologic units (extrusive basalts, intrusive gabbroic rocks, and mantle peridotites). It will also extend the sampling record to older lithospheric ages (up to ~30 Myr). The recovered samples will provide the first representative estimate of the bulk composition of the entire oceanic lithosphere and its secular compositional variation and allow a detailed assessment of the extent and mechanisms of hydrothermal alteration within the different lithologies of the oceanic lithosphere. In addition to structural information from the detailed bathymetry, the planned post-cruise petrological, chemical (major and trace element concentrations) and isotopic (radiogenic Sr-Nd-Hf-Pb and stable S-O-Fe-Mo isotope ratios) data will be used to investigate how structural and thermal conditions within the mantle and crust, and secular changes in mantle composition influence magma supply, magmatic evolution, hydrothermal alteration, and the compositional budget of the oceanic lithosphere. The results will provide novel constraints on elemental cycling between mantle, oceanic crust, and seawater, and the composition of the oceanic lithosphere that is eventually subducted back into the mantle, which is a crucial parameter for understanding the compositional evolution of Earth’s mantle.

• DFG Programme: Infrastructure Priority Programmes
• Subproject of: SPP 2520: Infrastructure area - Research Vessels
• International Connection: Finland, Italy
• Co-Investigators: Professor Dr. Wolfgang Bach; Dr. Felix Genske
• Cooperation Partners: Professor Dr. Christoph Beier; Professor Dr. Marco Ligi