Skip to Main Content
Book Chapter

Mechanics of thin-skinned fold-and-thrust belts: Insights from numerical models

By
Glen S. Stockmal
Glen S. Stockmal
1
Geological Survey of Canada, Natural Resources Canada, 3303 33rd Street NW, Calgary, Alberta T2L 2A7, Canada
Search for other works by this author on:
Christopher Beaumont
Christopher Beaumont
2
Dalhousie Geodynamics Group, Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada
Search for other works by this author on:
Mai Nguyen
Mai Nguyen
2
Dalhousie Geodynamics Group, Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada
Search for other works by this author on:
Bonny Lee
Bonny Lee
2
Dalhousie Geodynamics Group, Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada
Search for other works by this author on:
Published:
January 01, 2007

In order to investigate the development of structures at scales smaller than that of an entire belt, we examined aspects of the mechanics of thin-skinned fold-and-thrust belts in cross section using an arbitrary Lagrangian-Eulerian frictional-plastic finite-element model. A series of models, beginning with the deformation of a thick uniform layer above a thin weak layer on a fixed base, sequentially illustrates the effects of including flexural isostatic subsidence, strain-softening, multiple layers of strong and very weak materials, and finally erosion and sedimentation. These continuum models develop thin shear zones containing highly sheared material that approximate fault zones. The corresponding structures are similar to those in fold-and-thrust belts and include: far-traveled thrust sheets, irregular-roof and smooth-roof duplexes, back thrusts, pop-ups, detachment folds, fault-bend folds, break thrusts, and piggyback basins. These structures can develop in-sequence or out-of-sequence, remain active for extended periods, or be reactivated.

At the largest scale, the scale of the wedge, the finite-element model results agree with critical wedge solutions, but geometries differ at the sub-wedge scale because the models contain internal structures not predicted by the critical wedge stress analysis. These structures are a consequence of: (1) the complete solution of the governing equations (as opposed to a solution assuming a stress state that is everywhere at yield), (2) the initial finite-thickness layers, (3) the spatial and temporal variations of internal and basal strength, and (4) the coupling between surface processes and deformation of the wedge. The structural styles produced in models involving feedback with surface processes (erosion and sedimentation) are very similar to those mapped in the foothills of the southern Canadian Rockies and elsewhere. Although syndeformational sediments have been removed by postorogenic erosion across the foothills belt, evidence of the interaction between surface processes and deformation is preserved in the structural style.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Whence the Mountains? Inquiries into the Evolution of Orogenic Systems: A Volume in Honor of Raymond A. Price

James W. Sears
James W. Sears
Search for other works by this author on:
Tekla A. Harms
Tekla A. Harms
Search for other works by this author on:
Carol A. Evenchick
Carol A. Evenchick
Search for other works by this author on:
Geological Society of America
Volume
433
ISBN print:
9780813724331
Publication date:
January 01, 2007

References

Related

Citing Books via

Related Book Content
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal