Wessex Basin

[4] With the large interest in the hydrocarbon exploration of the area, data became more readily available, which improved the understanding of the type of inversion tectonics that characterize this basin.

[6] By mid Cretaceous the active crustal extension ceased and the region underwent a period of unfaulted subsidence in part due to the thermal relaxation effects from the earlier lithospheric action.

[3] Inversion began starting in the late Cretaceous and carried on through Cenozoic times coinciding with the Alpine orogeny happening at the now convergent boundary of the African and Eurasian plates.

[3] Starting at the basement of the structure, the area of interest overlies Variscan externides consisting of Devonian and Carboniferous sediments in imbricated thrust sheets.

[3] After the conclusion of the initial Hercynian deformation, normal reactivation of these same faults occurred along with differential subsidence beginning in the late Carboniferous as a direct result from the northwest/southeast trending wrench movements.

[4] The basin's inversion mechanism can be traced back to the movements of the Alpine orogeny that resulted in a series of monoclines along the boundary faults and the uplift of pre-Cenozoic sediments.

[3] Former structural highs underwent inversions to become areas where large amounts of sediments began being deposited, while also slowly deepening to the basement faults.

[3] Additionally, Eocene paleosols created during the late Cretaceous south of the Purbeck- Isle of Wight fault zone is a direct contrast of the marine sediments of the same age to the north.