Principles of shortening in salt basins containing isolated minibasins

Abstract

Shortening styles in salt-influenced basins can vary markedly, with the volume and distribution of salt prior to shortening being a key control. Here, we use a suite of physical models to examine styles of thin-skinned regional shortening in settings where the preshortening structure comprised minibasins surrounded by salt ('isolated- Highlights• In settings with isolated minibasins and a high salt volume, shortening induces salt flow.• The flow of salt contributes to the translation, tilt and rotation of minibasins during shortening.• A variety of factors control the amount and timing of minibasin translation, tilt and rotation during shortening.• The controls include, among others: boundary conditions, salt pressures, basesalt relief and whether primary and secondary welds have formed.• Fold-and-thrust belts in salt basins can vary in style, being strongly influenced by the volume and distribution of precursor salt.

From Salt‐Bearing Rifted Margins to Fold‐And‐Thrust Belts. Insights From Analog Modeling and Northern Calcareous Alps Case Study

“…After large‐transport thrusting, deformation transferred to the salt wall‐minibasin province. There, contractional deformation focusses on salt walls whereas minibasins are translated, jostled and eventually collided (Duffy et al., 2017, 2021) and rotated (Callot et al., 2016; Duffy et al., 2021; Ferrer, 2012; Rowan & Vendeville, 2006; Santolaria, Granado, et al., 2021) whilst broadly preserving their original architecture (Rowan & Vendeville, 2006). During salt wall squeezing, inherited roof thickness played a significant role.…”

“…Squeezing results in salt wall closure and secondary welding (e.g., Nilsen et al., 1995; Vendeville & Nilsen, 1995; Rasmussen et al., 1998; Ferrer, 2012; Roma, Ferrer, et al., 2018; Santolaria, Ferrer, et al., 2021; this work). Squeezing of vertical salt walls flanked by trough‐like minibasins results in relatively simple secondary welds, commonly localized along the maximum lateral expansion of minibasins (Duffy et al., 2021; Ferrer, 2012; Roma, Ferrer, et al., 2018; Rowan & Vendeville, 2006; Santolaria, Granado, et al., 2021). Conversely, in our models, the uneven inherited geometry of the salt walls and their flanks led to variable secondary weld geometries and tectonostratigraphic relations: interdigitated diapir shoulders and wings (Figures 11c and 11b), pinched secondary minibasins (Figure 8b) and welds that put in contact younger sequences with the oldest layers of the modeling package (Figure 8c).…”

“…Salt accumulations commonly localize deformation due to the inherent weakness of it (Weijermars et al, 1993;Letouzey et al, 1995;Rowan & Vendeville, 2006;Dooley et al, 2009;Ferrer, 2012;Duffy et al, 2018;Roma, Vidal-Royo, et al, 2018;Granado et al, 2021;. As observed in other analog modeling programs, salt bodies represent weak discontinuities within the modeling sand package that absorb most of the horizontal contraction (e.g., Koyi, 1988;Nilsen et al, 1995;Roca et al, 2006;Rowan & Vendeville, 2006;Callot et al, 2012;Ferrer, 2012;Duffy et al, 2018Duffy et al, , 2021among others). All in all, our results evidence the role played by the inherited passive margin architecture and especially the distribution of the model salt: (a) thick, distal raft model salt promote decoupling of the sub-and supra-salt deformation and the formation of a large-transport, source fed-thrust, (b) in the diapir-minibasin province, salt-walls localize deformation and account for most of the shortening accommodated in this area and (c) the distal model salt pinch-out control the deformation in the foreland.…”

Interplay between base‐salt relief, progradational sediment loading and salt tectonics in the Nordkapp Basin, Barents Sea – Part II

“…The sediment input and loading direction had shifted from the east to the NW and had caused the formation of mini‐basins to the northwest and intense salt evacuation to the south together with the rotation of the mini‐basins where base‐salt relief also facilitated the differential salt flow (Figures 13A3–B3, 14A9–A11, and 15A3–B3). The mini‐basin rotation also depends on the progradational sedimentation direction and contraction (Figures 8b,c and 9b) (Callot et al., 2016; Duffy et al., 2021; Fernandez et al., 2020). The salt depletion and sediment accumulation were now mainly focused in the CNB segment, and were gradually minimised within the NENB and SWNB segments (Figure 6b; Table 5).…”

The Role of Salt Tectonics in the Energy Transition: An Overview and Future Challenges

“…In the case of minibasins, recent studies have shown how minibasins exhibit complex subsidence and rotation histories as a result of, amongst others: tectonic shortening, interactions with base-salt relief, translation down salt-detached slopes, and mechanical interactions with other minibasins (e.g. Fernandez et al, 2020;Jackson et al, 2020;Duffy et al 2021). Such processes will have significant implications and thus should be constrained when reconstructing minibasin palaeo-topography.…”