HR: 1330h
AN: T12A-0437    [PDF]
TI: Diffuse Extension and the Formation of Non-Volcanic Mesozoic Rift Basins in the Northeast Atlantic
AU: * O'Reilly, B M
EM: bor@cp.dias.ie
AF: Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin, 2 Ireland
AU: Readman, P W
EM: pr@cp.dias.ie
AF: Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin, 2 Ireland
AB: Mesozoic rifting associated with regionally diffuse lithospheric extension occurred across the North Atlantic region and typically led to the formation of non-volcanic rift basins and margins. The deformation occurred over normal temperature or cooler asthenosphere at low strain rates and involved components of pure and simple shear. Two end-member sedimentary basin types are recognized as part of a kinematically coherent system of elements within the extended lithosphere between eastern North America and the European platform. These are compartmentalized by transfer/transform faults. The deep water Rockall and Porcupine Basins overlie lithosphere where large amounts of strain was focused into the upper-mid crust producing greater amounts of syn-tectonic subsidence. Abrupt discontinuities in the velocity field across regional transform fractures generated rotational strains in the southern Rockall and Porcupine Basins, while in the Celtic/Irish Sea Basins the stretching is lower (typically $\beta$ $<$ 2) and the strain field is largely translational. The cool thermal regime and the low strain rate inhibited basaltic melt production and led to the embrittlement of the upper lithosphere. The deformation drove seawater circulation and the exhumation and serpentinisation of mantle peridotites particularly along the regional transform fractures linking both the Porcupine and Rockall Basins. Strengthening of the lithosphere during this early phase of diffuse regional extension in the North Atlantic may have caused changes in the pattern of plate motion and mantle convection in the mid to late Cretaceous.
DE: 8100 TECTONOPHYSICS
DE: 8109 Continental tectonics--extensional (0905)
DE: 8159 Rheology--crust and lithosphere
DE: 9335 Europe
DE: 9609 Mesozoic
SC: Tectonophysics [T]
MN: 2003 Fall Meeting