Extensional fault-propagation folding and base-level change as controls on growth-strata geometries
✍ Scribed by Rob Gawthorpe; Stuart Hardy
- Book ID
- 104165319
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 578 KB
- Volume
- 146
- Category
- Article
- ISSN
- 0037-0738
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✦ Synopsis
Outcrop and analogue modelling studies indicate that upward widening zones of distributed deformation, often monoclinal folds, form above blind normal faults and are particularly common features at the depositional surface during the early stages of rifting. With increasing displacement (strain), such folds are cut by faults as they propagate upwards into the cover. We use a kinematic model of fault-propagation folding above a blind extensional fault, together with a sedimentary model of coarsegrained clastic deposition, to investigate growth-strata geometries associated with fault-tip monoclines. In particular, we consider coarse-grained deltaic deposition where sedimentary geometries are markedly different from the simple sub-horizontal 'fill-to-the-top' sedimentation used in most growth-strata models. For a given fault dip and slip rate, growth-strata geometries are strongly influenced by the fault-propagation to slip ratio ( p/s) and the width of the zone of distributed deformation. However, base-level changes also act as fundamental controls on sequence development. The results of a number of experiments compare favourably to well-documented examples of growth-strata. This study highlights the importance of integrating structural and stratigraphic studies in interpreting both fault/fold kinematics and the controls on stratigraphy; kinematic studies need to address the depositional geometry of stratal surfaces, whereas sequence stratigraphic interpretation of stratal patterns must deconvolve tectonic rotation and translation from depositional architecture.