The Post Triassic uplift and erosion history of the Southwestern UK

The passive continental margins which surround the North Atlantic region have been subject to widespread post-Triassic exhumation, the timing, magnitude and causes of which are debated. Exhumation of up to 6km (but more generally ≤3km) has been shown to have affected the Western UK Continental Shelf. This region contains a series of intra-plate extensional basins which formed during Permian-Jurassic rifting. Using a combination of palaeothermal (apatite fission-track analysis and vitrinite reflectance data) seismic and compaction data, this study has revealed an exhumation history of far greater complexity than previously suspected across the Southwest UK, with regional kilometer-scale exhumation episodes beginning during the Upper Triassic-Lower Jurassic (215-195Ma), Lower Cretaceous (140-120Ma), early Paleogene (75-55Ma), Eocene-Oligocene (35-20Ma) and Neogene (20-10Ma). Upper Triassic-Lower Jurassic exhumation appears confined to the footwalls of major basin bounding faults, suggesting footwall uplift was the principal cause of this episode of exhumation. Lower Cretaceous exhumation corresponds with continental breakup SW of Britain, suggesting a causative link. Early Paleogene exhumation was coeval with the Laramide phase of Alpine orogeny suggesting a causative link and additionally, marked heterogeneities in the pattern of this exhumation have been identified, casting doubt on the previously invoked role of plume-related epeirogenesis. Eocene-Oligocene and Neogene exhumation coincides temporally with the Pyrenean and Late Alpine compressional episodes. Seismic data shows that early and late Cenozoic exhumation was probably caused by compressional deformation related to Alpine orogenesis and/or Atlantic ridge-push. These observations imply that events at plate margins have exerted the primary control upon intra-plate exhumation in the Southwest UK onshore and offshore basin system with local faults providing an important control on the distribution of this exhumation

Name dc:type.qualificationname

d_ph

Level dc:type.qualificationlevel

d_ph

Grantor dc:publisher.institution

University of Birmingham

Year dc:date.issued

2011

Author dc:creator

• Kelly, John Edward

• GE Environmental Sciences
• GB Physical geography