ABSTRACT

The tectonic evolution of the Grand Banks involved several episodes of rifting and sequential development of the continental margin. The dominant period of rifting and basin formation in the central Grand Banks was late Callovian to Aptian. Extensional failure of the central Grand Banks crust probably occurred along a shear zone that dipped gently to the west. Listric normal basinforming faults merge at depth with this detachment system. The listric Murre fault soles at 26 km (16 mi), creating the very deep Jeanne d′Arc basin. Cross-basin transfer faults accommodated different amounts and rates of extension and resulted in the conspicuous offset pattern and funnel-shaped geometry of the Jeanne d′Arc basin. The Hibernia oil field is associated with one of these structural salients.

The stratigraphy of the Jeanne d′Arc basin and the Hibernia oil field is a direct response to this tectonic and structural framework. Large-scale, unconformitybounded sequences correspond to major plate reorganizations and zipper-type opening of the Atlantic Ocean. Smaller scale adjustments to episodic extension are expressed in multiple stacking of depositional sequences.The broad-scale evolution of the synrift succession involved the early deposition of limestones and oil-prone shales. About 10-12 m.y. later, rifting climaxed, resulting in floods of coarse terrestrial material from the rift shoulders.The characteristics of these depositional systems reflect a pervasive structural control affecting the distribution of facies tracts. Dip-slip movement on basinbounding faults and cross-basin transfer fault trends were equally important. A profound structural modification of the Hibernia structure occurred in late Barremian time when a major detachment developed within the basin fill. This structural modification and associated antithetic and synthetic faulting in the hanging wall largely controlled reservoir distribution and the maturation, migration, and trapping of hydrocarbons.

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