During Ocean Drilling Program Leg 129, two sites (800, 801) were drilled in Pigafetta Basin and one site (802) in East Mariana Basin, West Central Pacific. At all three sites, a thick (192–211 m) Cretaceous succession of dominantly volcaniclastic sediments was encountered, and at site 802 a further 222 m of Miocene-Pliocene volcaniclastics were drilled. These sediments are composed mainly of volcaniclastic material that has been resedimented downslope by various mass-flow processes including slumps, debris flows and turbidity currents. Sedimentary structures and textural variations observed in the recovered section can be used to calibrate the corresponding high-resolution Formation Micro-Scanner (FMS*) images and Dipmeter Micro-resistivity readings. Gamma ray log shapes show grain size evolution within a facies. Fining-upwards and coarsening-upwards grain size trends are observed for some sequences of turbidites and debrites. No obvious change in grain size is observed through massive structureless sandstones. CCA (calcium yield in decimal fraction) and CSI (silicon yield in decimal fraction) readings from the geochemical combination logs, correlated with visual compositional data, are useful to define calcareous and siliceous turbidite facies. This combination of wireline logs has been used in the poorly recovered intervals of volcaniclastic section in the ODP Leg 129 sites to improve significantly our understanding of basinal sedimentation and tectonics in the area.