Annotated record of the detailed examination of Mn deposits from DSDP Leg 56 (Holes 434B and 436)

The Japan Trench area was identified a favorable place for studying convergent margins during the initial deliberations of the IPOD Active Margins Panel. The Leg 56-57 DSDP drill sampling along the Japan Trench transect has indicated that material tectonically accreted during the present convergent episode is limited to a surprisingly small zone. The limits seem well established by the seaward extent of crust with continental thickness and lithologies and by the age and thickness of a terrigenous slope apron covering the presumed but probably unsampled accreted oceanic material.