Whale basin is part of the southern Grand Banks Mesozoic extensional mosaic. Basins in this domain were generated by cratonic extension before and during opening of the western Atlantic Ocean.

Long, relatively straight basement extension faults form the boundaries of Whale basin and are also important intrabasin elements. Some of these large faults are parallel to the trend of Paleozoic Appalachian tectonic elements, upon which the Mesozoic structures are superposed. The Mesozoic faults cut thick successions of Triassic and Jurassic terrigenous clastic strata and carbonates deposited during phases of crustal extension. A regional, planar unconformity separates those beds from drift-phase Aptian and younger rocks composing a seaward-thickening continental terrace wedge.

Immense, systematically aligned evaporite diapirs have intruded the synextensional rocks along basin-bounding faults and above clusters of sub-evaporite basement faults. A few small diapirs have risen from intrusive walls and penetrated terrace-wedge cover rocks.

Seismic evidence from Whale basin and other Grand Banks basins indicates that the geometries and motions of basement extensional faults can impose significant influences on the patterns, amounts, and times of salt intrusion. The diapiric patterns developed during rifting can be maintained by intraplate extension during postrift, passive-margin evolution.