MARIA S. MERIAN MSM70

The BATHYCHEM cruise aims to undertake high-resolution mapping and dense rock sampling of the poorly investigated intraplate volcanism along the Bathymetrists Seamount Chain and its corresponding fault zones; Cape Verde Ridge and Guinea Fracture Zone. Intraplate volcanism, in contrast to mid-ocean-ridge (MOR) oceanic crustal basalts, is formed by low degrees of mantle melting under thick lithosphere and thus has a unique and distinct major element, trace element and isotopic composition. Magmatism associated with the emplacement of this seamount province did not only directly alter the composition of the underlying lithosphere, but the magmatism triggered local structural changes and fluid flow causing large-scale hydrothermal activity, which would have modified the original composition of the lithosphere. The formation of the Bathymetrists Seamounts may have affected the composition of oceanic crust that has a wide range of ages from 30 to >100 Ma and thus has been exposed to variable degrees of seafloor alteration during the evolution of the seafloor. This project aims at characterizing the structure, age and composition of the Bathymetrists Seamounts and adjacent areas to understand their origin and formation mechanism, which will allow a better assessment of how intraplate volcanism modifies the structure and composition of oceanic lithosphere through time.