Evidence of early halokinesis in the Zechstein Group suggests the formation of Permian-Triassic carbonates build-ups offshore UK (Quad. 20-21)

The Upper Permian Zechstein Group comprises sequences of carbonate and evaporites, which extend over most of the onshore areas in North- West Europe, from Britain to Poland, and across the central and southern North Sea, bringing important economic value to hydrocarbon exploration. The nature and distribution of the evaporitic facies are key factors influencing the deposition, thermal evolution and the trap¬ping mechanism in the overburden section, as well as the sealing of the Early Permian-Carboniferous units under¬neath. The Zechstein Group includes source rocks from anoxic shale and microbialites, reservoirs from shallow water carbonate and several levels of seals from anhydrites and halite (Karnin et al., 1992; Cooke-Yarborough 1994; Slowakiewicz et al., 2013). The early salt movements have been tracked back to the Triassic and Jurassic (Glennie and Higham, 2003 and references therein), under different tectonic regimes between the Jurassic-Cretaceous rifting, to the Paleogene inversion, active in the remote foreland of the Alpine Orogeny. The lateral facies distribution has been largely described as a result of different subsidence rates and climatic fluctuation in the Zechstein Basin (Figure 1). Well data confirms the complex architecture of this basin at different scales (Geluk, 2000).