Transpressional inversion due to episodic rotation of extensional stresses in Jeanne d’Arc Basin, offshore Newfoundland

Variations in structural architecture indicate that a ninety degree rotation of extensional stresses occurred between multiple Mesozoic rift phases, resulting in local structural inversion in the Jeanne d’Arc Basin on the Grand Banks of Newfoundland, offshore eastern Canada. NW-SE-orientated extension caused dip-slip movement on NE-SW-trending en echelon faults during the Late Triassic to earliest Jurassic rift episode. These en echelon faults appear to have been separated by tilted basement relay ramps in accommodation zones rather than by cross-strike transfer faults. NE-SW-orientated extension during the mid-Aptian to late Albian rift episode resulted in oblique-slip reactivation and linkage of the earlier normal faults. Transpressional stresses were generated by oblique-slip motion at restraining bends in Jeanne d’Arc Basin faults. Structural responses include: ‘pop-up’ blocks between upward-diverging faults; reverse faults separating overlapping ‘shingles’ of strata; forced folds in strata overlying deep-seated faults; and wrench-related folds trending oblique to through-going transfer fault zones. Salt and shale layers are seen to act as horizons of fault detachment, modifying the transmission of tectonic stress and strain from the basement into the sedimentary cover. The transpressional mechanism and direction of strike-slip motion are confirmed through recognition of associated transtensional structures located along fault strike at nearby releasing bends. Transpressional structures in the Jeanne d’Arc Basin are recognizable over a wide range of scales from relatively large-scale reverse faults visible on seismic data to small-scale reverse faults seen in core.