Leg 190 is the first of a two-leg program of drilling along two transects in the Nankai Trough, the
type example of a convergent margin accreting a thick section of clastic sediments. The proposed
sites will define the interrelationship of the dynamics of deformation and fluid flow processes in an
accretionary prism characterized by thick terrigenous sediments. In situ measurements, including
logging while drilling, will provide critical information on stress, pore pressures, and permeability.
Sealing holes with advanced circulation obviation retrofit kits (ACORKs) will establish the
framework for long-term observation of fluid flow parameters and fluid geochemistry. Our
integrated structural, geochemical, and physical properties program will fully characterize the
factors controlling development of this accretionary prism.
Leg 190 will focus on core recovery from sites in undeformed to highly deformed zones along the
transects to investigate variability in deformational and hydrologic character. A second leg in 2001,
Leg 196, will involve logging the sites drilled on Legs 131 and 190 to obtain a first-order picture
of how physical properties change during accretion, as well as emplacing ACORKs for long-term
monitoring of fluid flow processes.
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