Physical models of fault-propagation folds /
Fault propagation folds form in compressional terraces ics.
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1998.
|
| Subjects: |
| Summary: | Fault propagation folds form in compressional terraces ics. and are the result of simultaneous folding and fault propagation. The resulting asymmetric fold has a steep to overturned forelimb and units may locally thicken or thin with continued fault displacement. The structure may also have an asymmetric syncline in the football of the thrust fault. Few structures are exposed and subsurface data is limited due to the difficulty in imaging beneath the overthrust block. As a result, several kinematic models have been proposed to explain the origins of fault-propagation folds. Although the kinematic models allow for thickening and thinning of layers, the deformation mechanisms responsible are still unconstrained, and the models do not show how different lithologies will respond to the inferred boundary conditions. In this study, physical models are used to investigate the effects of lithology and layering on deformation in basement- involved fault-propagation folds. All models produced a fault- propagation fold with a deformed football syncline and hanging wall anticline. In configurations containing a thick lower ductile unit the ductile layer absorbs a large amount of forcing block or ''fault'' displacement. This promotes folding in the overlying competent unit. In configurations with thin ductile units, there is less area available in the ductile unit to accommodate forcing block displacement. As a result, faulting initiates in the competent units at low displacements. The lead deforms internally by layer-parallel shear. If the lead layer is of sufficient thickness, it will accommodate all fault displacement and not transmit it to the limestone. If the lead layers are relatively thin, they accommodate less fault displacement and strains from the propagating forcing block are transferred to the surrounding limestone layers. In contrast, the clay deforms internally by layer-parallel shear and faulting. The clay layers accommodate limited fault displacement and transmit the associated strains to the overlying limestone layers. Changing the lithology and layering between configurations illustrates how fold geometry and kinematic development in rock models of basement-involved fault-propagation folds is dependent upon the deformation mechanisms, shear strength and thickness of layers in the overlying stratigraphy. |
|---|---|
| Item Description: | "Major subject: Geology". Vita. |
| Physical Description: | xiii, 120 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references: pages 113-115. |