Structural setting, geological development and basin modelling in the Rockall Trough

Abstract

Evidence from wide-angle seismic data in the Irish sector of the Rockall Trough suggests that the basin is underlain by thinned continental crust which has undergone differential stretching. The upper crust has been thinned by a stretching factor of 8-10 while the middle and lower crust (and probably also the lithospheric mantle) was stretched by a factor of 2-3. The latter figure is suggested as being representative of the overall lithospheric stretching. Crustal modelling fails to demonstrate any significant effect of the Iceland plume on the development of the basin. The Rockall Trough contains up to 6 km of sedimentary strata. Well and seismic data from adjacent basins indicate that the succession in the basin is likely to be of Late Palaeozoic to Recent age. The pre-Cretaceous facies are suggested to be broadly similar to other basins of the Atlantic borderlands. Cretaceous and Tertiary strata show progressive clastic starvation as thermal subsidence outstripped sedimentation in the basin. Sandy facies are likely to be concentrated towards the faulted basin margins and the re-entrant regions where the basin margin changes orientation. Basin modelling, based on normal incidence and wide-angle seismic profiles from a number of areas in the Irish sector of the basin, demonstrates that the observed seismic geometries and subsidence patterns cannot be explained by a single rift episode in the Cretaceous. The best fit of possible models suggests that the basin developed in response to discrete rift episodes in the Triassic, Late Jurassic and Early Cretaceous.

A review of the NE Atlantic conjugate margins based on seismic refraction data

“…Therefore, RAPIDS line 1 (Vogt et al 1998;Shannon et al 1999) is shown in Figure 4c as a landward extension of line CAM77. The two lines are separated by 140 km, which may explain the difference in the crustal thickness where the models are joined.…”

“…However, the resolution of the data is not sufficient to determine the COB based on the lower-crustal velocity distribution. Published Barton & White 1997) and RAPIDS line 1 (after Vogt et al 1998;Shannon et al 1999). The inset map displays the age of the oceanic crust (after Gaina 2014; cf.…”

“…This is consistent with a thicker continental crust beneath the Rockall Basin. Along RAPIDS line 1, the continental crust is stretched to a thickness of 5-7 km in a 200 km-wide zone (Shannon et al 1999).…”

“…3c) that is characterized by a three-layered continental crust with a total thickness of 28 -30 km (Bunch 1979;Shannon et al 1999). The Hatton and Rockall banks are separated by the Hatton Basin.…”

Controls on the location of compressional deformation on the NW European margin

“…Funck et al (2008) identified an extension of the HVLC beneath the northern part of the Hatton Basin below crystalline crust about 10 km thick, and interpreted this to be due to magmatic additions to the crust rather than partial serpentinization of the upper mantle. Further south, a zone of HVLC has been detected beneath the Hatton continental margin, overlain by crust in which the lower layer has been completely attenuated (Vogt et al 1998;Shannon et al 1999). The HVLC can be traced southwards beneath the SDRs on Edoras Bank (Barton & White 1997).…”