Development of N.W. Europe's Southern Permian Gas Basin

non-associated gas, most of which is found in Early Permian Rotliegend sandstones. The most important source of this gas is Carboniferous coal deposited in a proto-Tethys foredeep basin. Where the coals were overlain by Rotliegend esert sands and by Late Permian Zechstein halite, he scene was set for creating important reservoirs for gas. Deformation of the reservoir and seal to create a trap, and the generation and migration of Carboniferous gas, resulted from the structural history of the area, which was shaped in part by underlying crustal blocks and zones of crustal weakness. Much of this history was related to events most clearly expressed beyond the limits of N.W. Europe in the North Atlantic and Tethys: (1) E.-W. tension, which gave rise to the oblique-slip-induced subsidence of many sub-basins within the Southern Permian Basin, caused the consecutive creation of the Viking-Central graben system and Rockall Trough, and ended with the crustal spreading of the Atlantic Ocean; and (2) the early Mesozoic opening of Tethys, its Cretaceous closure and nsuing Alpine orogeny, which induced inversion in many areas of the Southen Permian Basin that are now gas bearing