Deep sea diapirs and bottom simulating reflector in Fairway Basin (SW Pacific)

A recent swath-bathymetry and geophysical survey of the R/V L'Atalante in t he Fairway Basin between Australia and New Caledonia allowed to confirm the Cretaceous age of the creation of the basin by continental stretching. Thi s first stage of opening of the Fairway Basin is associated with the deposi tion of a continuous salt/mud layer feeding today numerous diapirs, some of them piercing the 3 to 4 km thick sedimentary cover and reaching the seafl oor. In close link with this salt/mud layer a Bottom Simulating Reflector i ndicator of gas hydrates level occupies a 70 000 km(2) surface at about 500 to 600 m-depth beneath the sea floor. The coexistence of both BSR and diap irs suggests a thermogenic better than biogenic origin for the gas hydrates horizon.