COMPRESSIVE TECTONISM ALONG THE EASTERN MARGIN OF MALAITA ISLAND (SOLOMON-ISLANDS)

New bathymetric and geophysical data were collected in the region east of the island of Malaita during the SOPACMAPS II cruise of the French research vessel L'ATALANTE. This region, part of the Malaita Anticlin orium was interpreted as a piece of oceanic crust from the Ontong Java Plateau obducted over the old Solomon Islands are during collision be tween the Pacific and Australian plates. It has been generally accepte d that convergent motion between the Australia and Pacific plates sinc e the Late Miocene was absorbed exclusively along the San Cristobal tr ench, southwest of the Solomon Islands Are. Bathymetry, imagery, and g eophysical data (magnetism, gravity, seismic) acquired during the SOPA CMAPS II survey allow us to classify the successive parallel ridges ma pped within the region as being recent volcanic, oceanic crust, or def ormed sedimentary ridges. Seismic profiling provides evidence of succe ssive compressive events along the Malaita margin caused by the relati ve motion between the Solomon Islands and the Pacific plate. The main phase of convergence probably occurred during Oligocene-early Miocene time, but some relative motion between the two domains are still being absorbed along the East Malaita boundary. The existence of active fau lting in the sedimentary cover throughout the region and the present-d ay deformation of the outer sedimentary ridge is a good illustration o f this phenomenon.