Structural investigations have shown that the basin fill of the Forlandsundet Graben, Svalbard, has suffered stronger deformation than previously assumed. From plate-tectonic reconstructions it is known that the basin was initiated in a regional, dextral transpressional environment. During its early history, the basin may have been wider than its present outline, and syn-depositional deformation of the basin sediments was common. Later, the basin fill was affected by regional folding and local thrusting, probably in relation to continued strike-slip movements. The most intense deformation is localized in certain areas which may have acted as restraining bends of the graben margin. This event was followed by mild inversion of the basin margins. The inversion is now traced as compressional, margin-vergent structures. Several systems of extensional fractures are developed. These clearly post-date the compressional event.

Roy H. Gabrielsen, Geological Institute, Dept. A., University of Bergen, Allégaten 41, N-5007 Bergen, Norway. Present address: Norsk Hydro Research Centre, Bergen, P.O. Box 4313, N-5028 Bergen, Norway;
Oddbjørn S. Kløvjan, Hild Haugsbø, Eigil Rasmussen & Pål H. Skott, Norsk Hydro a.s., Harstad Office, P.O. Box 31, N-9401 Harstad, Norway;
Peter S. Midbøe, Norsk Hydro a.s., Vækerø, P.O. Box 200, N-1321 Stabekk, Norway;
Arvid Nøttvedt, Norsk Hydro Research Centre, Bergen, P.O. Box 4313, N-5028 Bergen, Norway.