The Jeanne d'Arc Basin, located at the northeastern part of the Grand Banks of Newfoundland, is a Mesozaic failed-rift basin containing in excess of 22 km of sedimentary fill. Despite a period of vigorous exploration activity initiated by the discovery of the giant-class Hibernia oil field in 1979, the lithostratigraphic nomenclature is not yet standard. This has led to a plethora of lithostratigraphies used by various industry groups, government agencies, and academia, a situation that has caused communication problems. A new lithostratigraphic nomenclature is proposed for the Mesozaic rocks older than the Late Cretaceous Dawson Canyon Formation. The nomenclature consists of 17 formations (14 new), 3 members (new), and 2 markers (new). The sedimentary evolution of the Jeanne d'Arc Basin is a response to the structural framework of the basin and to regional tectonic episodes related to the breakup of Pangea. Two periods of rifting, the first dominated by deposition of evaporites and the second by coarse clastics, are separated by a tectonically quiet period characterized by the deposition of fine clastics and limestones. A two-stage transition to a passive continental margin followed when fine clastics and minor chalky limestones were deposited. Major reserves of oil have been discovered in the basin. The oil was generated after continental breakup in shales deposited at the end of the tectonically quiet period and is now trapped mainly in stacked sandstone reservoirs deposited during the second period of rifting. Geological and geochemical data indicate that perhaps as little as 10 percent of potential recoverable reserves have been discovered.

Late Paleozoic reconstructions of the North Atlantic juxtapose the eastern margin of the Grand Banks with the continental margin off Iberia. Comparison of the geology of the Grand Banks region with results from ODP Leg 103 on the Galicia margin improves our understanding of the Mesozoic-cenozoic tectonic evolution of these regions and provides new constraints on pre-drift fits.The Grand Banks region is underlain by Paleozoic and Precambrian rocks of the Appalachian Orogen, which were rifted, eroded, and buried during Mesozoic and Cenozoic tectonic episodes related to formation of the North Atlantic Ocean and the Labrador Sea. The Carson Basin along the eastern margin of the Grand Banks contains Triassic and Jurassic evaporites overlain by Jurassic and Cretaceous carbonate and clastic rocks that were deeply eroded during the mid-Cretaceous. This unconformity is overlain by a comparatively thin and undeformed sequence of Cretaceous-Tertiary fine-grained marine elastics. Since the mid-Cretaceous, the outer portion of the Carson Basin has subsided to oceanic depths and now underlies the slope-rise zone. Comparison of the seismic stratigraphy of the Carson Basin with that of the Galicia margin indicates similar tectonic histories and depositional environments from Triassic to Tertiary time. Seismic-reflection data have been used to map the minimum seaward extent of continental crust, and this boundary lies approximately along a "headland to headland" line between the Newfoundland Ridge and Flemish Cap. Regional juxtaposition of these margin segments is geologically reasonable, but the evidence for continental crust beneath the slope and rise southeast of the Grand Banks precludes fitting Galicia Bank in this zone.

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A series of Mesozoic sedimentary basins extends across the broad continental shelf of Newfoundland. So far it has been demonstrated that only the Jeanne d'Arc Basin and environs contain potentially commercial quantities of oil and gas. The development in this area of hydrocarbon source rocks, reservoir rocks, source rock maturity, and hydrocarbon migration and trapping mechanisms was controlled by the cyclic development of extensional forces related to the opening of the North Atlantic Ocean. Geophysical exploration of the Grand Banks region began in the early 1950s. The first industry seismic program for the Jeanne d'Arc Basin was undertaken by Amoco in 1965. Drilling in the Jeanne d'Arc Basin and environs began in 1971 and, after a hiatus from 1975 to 1978, drilling activity peaked in 1984. A total of 67 wells have been drilled, and over 150 000 km of seismic data have been recorded in the study area to the end of 1989. In Part I of the report, 15 hydrocarbon exploration plays are defined by area and type of trap and by the lithostratigraphic horizon providing the reservoir facies. In Part II, seismic and well data for each play are used as input data in statistical estimations of the total and remaining hydrocarbon potential of the Jeanne d'Arc Basin and environs.

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