Figure 2. A. Line X-X' showing ISC earthquakes occurring between 1964 and 1990 with Mb in the range of 4.5 to 5.5 in the northern Solomon Islands (SI) (see Figure 1 for location of X-X', Y-Y' and Z-Z'). Larger open circles indicate earthquakes with Mb = 6.0. Dotted lines in all three sections indicate inferred top of subducting plates. Gray area in all three sections represents approximate cross sectional area of the Malaita "anticlinorium" (MA), an accretionary wedge formed by offscraping of basalt and pelagic sediment from the active subduction of the Ontong Java oceanic plateau (OJP) at the North Solomon trench (NST). B. Line Y-Y' roughly parallel to our MCS/OBS line showing earthquakes in the central Solomon Islands. Incipient subduction of the Louisiade Plateau (LP) is occurring at the San Cristobal trench (SCT) along the southeastern edge of the Solomon island arc. C. Line Z-Z' showing earthquakes in the southern Solomon Islands. Intense seismicty and higher relief is attributed to local convergence between Ontong Java and Louisiade Plateaus on opposite sides of the Solomon island arc. D. Near trace plot of multi-channel seismic line collected during EW95-11 across the North Solomon trench (location on Fig. 1). Folds and active thrusts breaking seafloor sediments indicate ongoing subduction of the Ontong Java oceanic plateau. Parallel reflectors are inferred to be post-Middle Eocene to Recent pelagic sedimentary rocks. More discontinuous reflectors in packet 2 are inferred to be Lower Cretacous to Middle Eocene pelagic sediments and poorly resolved section in packet 3 is inferred to be Lower Cretaceous basaltic basement of the OJP. Packet 1 is being accreted to form the Malaita "anticlinorium" or accretionary prism while packets 2 and 3 are subducted with the level of detachment near presumed Middle Eocene cherts above volcanic basement of the OJP.

From:
Mann, P., Coffin, M., Shipley, T., Cowley, S., Phinney, E., Teagan, A., Suyehiro, K., Takahashi, N., Araki, E., and Miura, S., 1996, Researchers investigate fate of oceanic plateaus at subduction zones: EOS, Transactions of the American Geophysical Union, v. 77, no. 30, July 23, 1996, p. 282-3.

Copyright 1996 American Geophysical Union. Further electronic distribution is not allowed.