Nankai Trough A complex interplay of deformational, diagenetic, and hydrologic processes massive sulfide deposits and associated ores in ancient marine sequences. This knowledge is necessary to create a new science base for mineral exploration on the continents. These types of deposits probably formed at convergent continental margins, rather than at mid-ocean ridges. Many represent multi-billion dollar resources. ODP will drill below both focused and diffuse outflow zones, into a likely seawater inflow, and will also drill a reference hole.
Plans call for one hole to be CORKed as a geochemical observatory.
The leg also requires microbiologists to study the deep biosphere. Emplacement rates of the largest LIPs may have approached the entire magma production rate of the global mid-ocean ridge system. Leg 193 is the first leg in a proposed two-leg program aimed at understanding the formation of the world's largest plateau. A transect of holes into basement across the Ontong-Java Plateau associated with initial mountain building processes occurs within accretionary prisms. Key questions relate to the distribution of deformation, the controls on what material is accreted and what is subducted, and the role of fluids and fluids flow in the prism's deformation.