Geology of the southern North Sea
[3] The overall saucer-shaped geometry of the southern North Sea Basin indicates that the major faults have not been actively controlling sediment distribution.
[3] The Caledonian event occurred due to the collision of three land masses – Laurentia, Baltica, and Avalonia – which would eventually lead to the creation of Pangea.
[5] Late Permian deposition of evaporites created the Zechstein supergroup which act as a salt cap for the fine grained sediment.
[1][6] During this era the end of extensional tectonics had been well constrained in the southern North Sea basin; the extension occurred from the late Carboniferous to the Triassic.
[5] Due to the Kimmerian phase uplift in the northern portion of the North Sea, it allowed subsidence and deposition to fill the basin, creating sandstone.
This inversion event was followed by deposition of upper Carboniferous red beds, which pass up into sands of the Permian Rotliegend Group; these are overlain by evaporites of the Zechstein Supergroup.
[1] Since the orogeny reactivated the Mesozoic rifts it permitted the Zechstein salts to act as a buffer or detachment layer separating two structural regimes,[3] which can lead to traps for natural resources.
Through time eventually Avalonia coming from the south closing the Iapetus ocean, collided with the two landmasses to create a T-junction giving an East to West trend in the southern portion.
The tectonic event comprised the entire Ordovician and into the early Devonian, the Caledonian rocks are the basement of the current North Sea.
[3] The second phase, the Sudetian, was of volcanic event and extrusive metamorphic and igneous rocks with uplift and mild folding of grabens in the vicinity which lead to inversion.
[3] The break up of Pangea occurs during the Kimmerian tectonic phase for most of the Mesozoic, until the early-mid Cretaceous, this marks the start of creating the present position of our continents today.
[10] Regional uplift and erosion allowed the unconformity to appear in the late Triassic and depositing the Cromer Knoll and chalk groups.
Within the southern North Sea basin this plays a huge role in the oil and gas industry because the tectonic events throughout the geologic timescale allowed these halokinesis structures to trap areas of natural resources.
The German basin can be categorized as a salt wall which is a linear diapiric structure possibly related either to basement faulting or to the controlling effect of regional dip, and the English basin is categorized as a salt pillow type of structure, developed in association with thinning of overlying beds but without diapiric effects.
[3] The sandstone deposited prior to the Zechstein evaporites are essentially the area in which the oil industry is pulling the natural resources from due to high quality seal from the salt diapirs and pillows which acted as a buffer between structural segments.
