Origin and influence of the Top Dinantian surface of the UK southern North Sea

Seismic reflection data, Bouguer gravity data, well information and velocity data were interpreted over the entire UK sector of the southern North Sea. The seismic data were depth converted and 2D gravity modelled to help determine the Top Dinantian and the location and trend of deep-seated intrusives. By correlating and further interpreting these it is evident that many Top Dinantian faults and some intrusions have an Acadian trend. Major and more deep-seated NNW-SSE trending lineaments were also delineated and are taken to represent a basement with a Charnoid trend. The "northward" movement of the Midlands microcraton probably formed Acadian faults in the southern North Sea and reactivated the NNW-SSE lineaments. The resulting interference pattern was to play an important role in the later development of the basin. Offshore intra-Dinantian differential movement in a dextral shear system that re-used Acadian faults, resulted in the formation of the Flamborough Head and South Hewett basins. Consequences of the sinistral reactivation of the NNW-SSE trending lineaments and most overlying Acadian faults during Variscan tectonism was the development of en echelon Top Dinantian folds along the western parts of the southern North Sea, the formation of Reidel shears at Top Dinantian level and the development of Reidel flakes. This last phenomenon is used to explain the more widespread regions of uplift and depression during tectonism. The structure at Top Dinantian level is further complicated by the significant local tectonic control of Acadian granites. Rotliegend deposition in the Sole Pit basin may have been influenced by the extensional reactivation of Acadian faults and the boundary between aeolian/wadi and sabkha sediments approximately coincides with E-W Variscan displacement zones. Zechstein salt diapirism and Mesozoic deposition was initiated and influenced by the reactivation of Acadian and Variscan faults