Table 1.

The full suite of stratigraphic horizons used for backstripping, plus their age and associated bulk lithologies (used to constrain decompaction)

Horizon No.Horizon nameAge (Ma)% sand (interval above horizon)% shale (interval above horizon)
1Base Quaternary1.82080
2Top Balder Formation54595
3Base Tertiary651090
4Intra-Upper Cretaceous72.4595
5Top Lower Cretaceous98.9595
6Base Cretaceous1402080
7Intra-Upper Jurassic*1552080
8Top Middle Jurassic1702080
9Top Basement2505050
  • * Interpolated synrift horizon, half-distance between horizons 6 and 8. Broadly equivalent to the top of the Heather Formation (base of the Kimmeridge Clay/Draupne Formation).

  • Extrapolated as an isochore 2 km below the mapped Top Triassic. The Top Triassic is not included in the backstripping model because of a restriction (up to 10) on the number of horizons which can be included.