Major and trace elements, Sr-Nd-Pb isotope data of lavas from D. João de Castro seamount, Azores

The D. João de Castro seamount is located on the ultraslow diverging Terceira Rift, Azores. D. João de Castro is a young central volcano (<0.5 Ma) with recent volcanic and hydrothermal activity. The central volcano is located on a volcanically active fissure zone where two volcanic ridges extent rift-parallel from the edifice. Submarine lava samples and volcanic glasses were taken from D. João de Castro volcano and the adjacent submarine volcanic ridges (N and NW Castro Ridges). Samples range from the uppermost flanks at ~300 m water depth to ~1350 m water depth at the NW and N Castro Ridges. Samples were taken by TV-guided grab (GEOMAR Helmholtz-Zentrum für Ozeanforschung) and with a Remotely Operated Vehicle (ROV MARUM Quest 4000) during cruises M113 and M128 with the German research vessel R/V Meteor in 2015 and 2016, respectively. Major element concentrations of all lavas were analyzed in order to estimate the compositional variability of the edifice and the volcanic ridges. Trace element and Sr-Nd-Pb isotopes analyses where then carried out on selected lavas to reconstruct the mantle source signatures and the conditions of melting under which lavas from D. João de Castro formed. The sampling of these volcanic formations was designed to improve our understanding of how central volcanoes are formed in oceanic rift systems.