The Jeanne d'Arc Basin is an offshore sedimentary basin located about 340 kilometres (210 miles) to the basin centre, east-southeast of St. John's, Newfoundland and Labrador. This basin formed in response to the large scale plate tectonic forces that ripped apart the super-continent Pangea and also led to sea-floor spreading in the North Atlantic Ocean. This basin is one of a series of rift basins that are located on the broad, shallow promontory of continental crust known as the Grand Banks of Newfoundland off Canada's east coast. The basin was named after a purported 20 metres (11 fathoms) shoal labelled as "Ste. Jeanne d'Arc" on out-dated bathymetric charts and which was once thought to represent a local exposure of basement rocks similar to the Virgin Rocks.
Basin formation The upper crust beneath the wide shoals of the Grand Banks region is composed of old Precambrian and Paleozoic strata that were moderately deformed by compression during the collisions of ancient continental plates during final assembly of the super-continent Pangea in Devonian to Carboniferous times. Later, these old 'basement' rocks were subjected to multiple episodes of stretching during the Mesozoic and the strain of that extension was expressed in growth of large rips in the rock fabric known as faults. The crust was thinned in areas of stretching and the synchronous growth of faults allowed those areas to subside; that is, to sink relative to surrounding areas, thereby creating rift basins. The Jeanne d'Arc Basin is one of these areas of rift subsidence that is bounded and transected by extensional faults which record the plate tectonic history of the North Atlantic region. As the Jeanne d'Arc rift basin subsided, it was gradually in-filled with sediments eroded from adjacent areas of crustal uplift. Characteristics of the sedimentary basin fill and their relationships to the extensional history of the Jeanne d'Arc Basin have been variably described by numerous authors with general agreement on the applicability of rift concepts to the basin. There are, however, divergent conclusions regarding the number of Mesozoic rift episodes which affected the Jeanne d'Arc Basin (i.e. two or three), their ages of initiation and duration, and the orientations of extensional stresses that created different fault sets active during the rift episodes. Rift episodes were followed by initiation of sea-floor spreading first to the south, then to the east, and finally to the northeast of the Grand Banks area. Widely faulted 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.
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