Deep Sea Drilling Project Legs 59 and 60 drilled 15 sites along an east-west transect at 18°N from the West Philippine Basin to the Mariana Trench (Fig. 1) in order to study the nature and genesis of the back-arc, marginal basins and the remnant and active arcs of the region. Leg 59 drilled at five sites at the western end of the traverse: Site 447 in the West Philippine Basin; Site 448 on the Palau-Kyushu Ridge; Sites 449 and 450 in the Parece Vela Basin; and Site 451 on the West Mariana Ridge. Penetration into basaltic basement of these sites was 183.5 meters at 447 (8 basalt flows); 623 meters at 448 (46 basalt flows, sills, and dikes and volcaniclastic units); 40.5 meters at 449 (2 basalt flows); 7 meters at 450 (1 basalt intrusion); and 4 meters of basalt breccia at 451 overlain by 861 meters of volcaniclastic sedimentary rocks.

Supplement to: Wood, D A; Mattey, David P; Joron, Jean Louis; Marsh, Nicholas G; Tarney, J; Treuil, M (1981): A geochemical study of selected samples from the basement cores recovered at Sites 447, 448, 449, 450, and 451, Deep Sea Drilling Project Leg 59. In: Kroenke, L; Scott, R; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 59, 743-752