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

Abstract

Analog modeling is used to study the role played by the inherited salt-sediment architecture of a salt-bearing rifted margin, developed by minibasin downbuilding and margin-scale gliding, and then incorporated into a fold-and-thrust belt system influenced by surface processes. Inherited salt bodies localize contractional deformation at different scales and the salt-sediment architecture determines structural styles of fold-and-thrust belts. In our analog models, a large-transport thrust detached along allochthonous model salt (silicone polymer) accumulated in a former distal raft system. And the squeezing of salt walls, together with the tilting of minibasins, accounted for most of the shortening in a salt wall-minibasin province. Shortening and surface processes promote the extrusion and erosion of about 75% of the original model salt. The role played by salt tectonics during the contraction of salt-bearing rifted margins could be underestimated because of the low salt-sediment ratio found in fold-and-thrust belts. Our modeling results are compared with and assist in the interpretation of a section along the Northern Calcareous Alps.