Processed multichannel seismic data in the Solomon Islands convergent zone, Southwest Pacific Ocean, acquired during the R/V Maurice Ewing survey EW9511 (1995)

A U.S.-Japan cooperative program to map crustal and perhaps upper mantle structures in the Solomon Islands convergent zone. Due to a major cable loss on the previous cruise the cable configuration varied between 112 and 128 channels as new sections were repaired or on-loaded (see cruise report). Japanese OBS's were used in this experiment along line SI-1. The primary objective of the MCS study and an independently proposed OBS study by Drs. K. Suyehiro and colleagues at the Ocean Research Institute in Tokyo, Japan, is to test two models for the formation of the Malaita anticlinorium - the deformed wedge of Cretaceous-Cenozoic pelagic limestone, basalt, and clastic rocks that most previous workers agree to be an emergent part of the Ontong Java Plateau. One model predicts tectonic wedging of the Solomon island arc beneath the Ontong Java plateau. A second, alternative model predicts a more familiar oceanic accretionary wedge geometry with northeastward (plateauward) offscraping and thrust imbrication of plateau rocks. Our proposed MCS-OBS study focusing on the Malaita anticlinorium and North Solomon trench will use state-of-the-art data acquisition and processing techniques to address fundamental questions concerning the subduction/accretion/fragmentation of oceanic plateaus at subduction zones and their deformational effects on the overriding island arc-including collision-related arc polarity reversal. Answers to these questions are important for understanding how oceanic plateaus may contribute to growth of continents through time and how subduction zones initiate by polarity reversal. Funded by NSF grant OCE9301608.