*2.2. Restoration of Faults*

Several algorithms exist for restoring the structural evolution of basins. The different algorithms result in different basin and fault geometries, which again impact the calculated thermal history. Commonly, basin modeling simplifies the structural reconstruction of basins, e.g., by not reconstructing the faults through time, regardless the fact that hydrocarbons often accumulate in complex geological structures associated with faults [26]. According to Dula [40] reconstruction with simple inclined antithetic shear of 20◦ is one of the methods that best represents the observed fault shape, but all tested reconstruction methods in that study gave adequate results.

The present study utilizes vertical shear as a standard fault reconstruction method. However, different segments of simple shear, including inclined antithetic and synthetic shear are explored (Figure 2). Furthermore, we investigate how the different resulting geometries impact the thermal history. Because BMT restore faults solely by vertical shear, and the software Move (Petex Ltd.) does not have the ability to perform thermal and maturation modeling, both Move and BMT were used to model the structural development of the section. In the restoration process BMT and Move both use the backstripping process, which removes layers one by one and decompact the underlying sequences based on the given porosity-depth trend for the assigned lithology/lithologies. The porosity calculations are based on exponential functions (cf., [37]) and the same values are used in both softwares (Table 2). Move is a commercial software restoring geological cross sections by kinematic algorithms. Six algorithms are available for fault restoration, these are: simple shear, fault parallel flow, fault bend fold, fault propagation fold, trishear, and detachment fold. BMT is a non-commercial basin modeling software with the ability to perform fault restoration (by vertical simple shear) so that structural effects on temperature estimates are accounted for (cf., [26]).

**Figure 2.** Illustration of the technique of (**a**) vertical simple shear, (**b**) antithetic inclined simple shear and (**c**) synthetic inclined simple shear. Antithetic simple shear results in a broader basin compared to for instance synthetic shear. Modified after Fossen [41].

In our study Move was used to restore the fault by antithetic and synthetic inclined shear. The tested angles for inclined shear are summarized in Table 1. The resulting reconstructions from Move are replicated in BMT by utilizing a "volume editing" function (cf., [26]). This method enables calculations of the thermal histories for the different restoration methods. All models have the same starting geometry. However, through restoration by different algorithms the paleo geometries will differ and so will the temperature histories.
