Lower crustal structure of the East Irish Sea from deep seismic reflection data

Deep near-normal incidence reflection profiles across the East Irish Sea show that the middle and lower crust are dominated by dipping reflectors with a NE-SW strike. The northward dipping Iapetus suture can be traced and contoured beneath the Solway Firth where it projects upward beneath the Peel and Solway Firth basins. South of the suture there are both northward and southward dipping reflectors. These are considered to be related to Early Devonian (Acadian) deformation. Although the Carboniferous was deposited in basins with a broadly NE-SW trend there is no clear evidence of reactivation of earlier structures during either Carboniferous sedimentation or Variscan inversion. The faults that controlled Permian and Mesozoic basin development in the East Irish Sea are at a high angle to Caledonian and Acadian trends and are considered to be juvenile structures which developed in the late Westphalian.