Annotated record of the detailed examination of Mn deposits from DSDP Site 113, Leg 12 (Cores 113-3, 113-11)

Seismic reflection profiles across the Labrador Sea by Vema-19 and Charcot-S had revealed a rugged basement topography almost entirely buried by sediments up to 2000 meters thick. It was first suggested that this was the median valley of a mid-Labrador Sea ridge where oceanic crust was generated during the last phase of opening of the Labrador Sea but which is now virtually inactive and covered by sediment. The choice of a site where basement could be dated by sampling sediments that were believed to be the same age as the basement was difficult. Site 113 was eventually chosen in a local valley 8 kilometers south of a small knoll believed, from the Vema-ll record, to be a basement high.