and moderately rotated Upper Triassic to Lower Cretaceous beds within the rift basin were subsequently buried beneath a relatively unstructured cover of Upper Cretaceous and Tertiary strata. These latter minimally deformed strata were deposited on the newly established passive margin. The current passive margin conditions were established when the last rifted border to the three-sided promontory of continental crust underlying the Grand Banks bathymetric feature formed along its northeast margin near the start of Late Cretaceous times. Geology and hydrocarbon prospectivity Effective combinations of a number of geological factors must occur for a basin to have generated, trapped and preserved hydrocarbons (oil and/or gas). The nature of the sediments deposited during and after the three rift episodes which affected the Jeanne d'Arc Basin and the numerous complex structures formed in response to the changing stress regimes through Mesozoic time have proven critical to the basin's hydrocarbon prospectivity. First, large volumes of halite salt of the Argo Formation were precipitated in the basin during the Late Triassic to earliest Jurassic. These salt beds with interbeds of dolomite were precipitated atop and adjacent to continental clastic facies (alluvial plain sandstones and red shales) of the Eurydice Formation. The presence of this thick salt unit throughout the Jeanne d'Arc Basin has been an important factor in subsequent structural deformation and hydrocarbon trap formation during later rift episodes. It provided a widespread interval of low shear strength which acted as a sub-horizontal detachment horizon between vertically stacked zones of strain. Consequently, precipitation of salt during the first Mesozoic rift episode resulted in partial isolation of crustal extension from extension and creation of structural traps of the overlying sedimentary column during subsequent rift episodes recognized in the Jeanne d'Arc Basin. One element that is absolutely essential for successful exploration and development is the presence of a stratigraphic unit that is capable of hydrocarbon generation. The presence of an excellent quality Upper Jurassic source rock in the Jeanne d'Arc Basin was first identified in well cuttings from the Egret K-36 exploration well. This Kimmeridgian package of organic-rich, thinly interbedded and finely laminated marlstones and calcareous shales was formally defined as the Egret Member of the Rankin Formation. These economically important beds have been demonstrated to be present across the Jeanne d'Arc Basin. Microscopic analyses identified abundant bituminous/liptinitic detrital material and a lack of terrestrial organic matter. These characteristics indicate that the Egret Member is dominated by