Using laterally compatible cross sections to infer fault growth and linkage models in foreland thrust belts. (March 2017)

• Record Type: Journal Article
• Authors: Watkins, Hannah; Butler, Robert W.H.; Bond, Clare E.
• Is Part Of: Journal of structural geology. Volume 96(2017:Mar.)
• Page Start: 102
• Page End: 117
• Publication Date: 2017-03
• Subjects: Fold-thrust -- Laterally compatible cross-section -- Thrust growth -- Thrust linkage -- Displacement transfer -- French Alps; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2017.01.010
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: We investigate changes in shortening, displacement and fold geometry to understand the detailed along-strike structural variation within fold-thrust belts, and infer thrust growth and linkage mechanisms. Field observations from the Vercors in SE France are used to characterise deformation style in the region. Parallel cross sections are constructed, analysed and used to create shortening and thrust displacement profiles from the northern to southern Vercors. Sections show changes in structural style and shortening accommodation from thrust-dominated in the north to fold-dominated in the south. The total shortening distance in the Vercors does not change significantly along strike (3400–4650 m), however displacements along individual thrust zones do vary significantly and displacement profiles show a range in displacement gradients (16–107 m/km). Despite relatively simple shortening patterns in the Vercors, sections show a more complex 3D internal structure of the fold-thrust belt. Thrust displacements and geometries suggest both large-scale thrust zones and small-scale thrusts are soft linked, transferring displacement along strike through transfer zones. Short, soft-linked thrust segments indicate an intermediate stage of thrust growth and linkage, well documented for normal fault systems, which form prior to the formation of thrust branches and hard-linked displacement transfer. Graphical abstract: Highlights: We construct parallel cross sections through the Vercors foreland thrust belt. Cross sections are analysed to ensure lateral continuity. Displacement profiles show displacement transfer between thrust zones. Fault properties suggest thrusts evolve through soft-linked and hard-linked stages.