|
Fault Geometry and Associated Processes |
Centre Armorican d’Etude Structurale des Socles, (Laboratoire C.N.R.S. Conventionné à l’Universite de Rennes), Campus de Beaulieu, 35042 RENNES Cédex, France
Laboratoire de Tectonique, Université de Paris VII, 4 Place Jussieu, 75007 PARIS, France
In a preliminary series of experiments, using physical models mechanical processes of extensional tectonics have been investigated at various scales. By a suitable choice of model materials, experiments were performed at low cost in a natural gravity field. Upper layers of the lithosphere were modelled using sand; lower layers, using silicone putties of two different densities; the mantle asthenosphere was modelled using honey. The models deformed under their own weight or under absolute horizontal tension. Rates of extension were controlled using a stepper motor. Surface deformation and faulting were monitored using 35 mm time-lapse photography. Lower lithosphere topography was photographed through the transparent asthenosphere. Fault patterns in models with lithosphere only, were observed by serial sectioning. Otherwise, the brittle-ductile interface was observed after suctioning off the sand.
Simple experiments with uniformly extended sand layers only show that; (i) spacing of normal faults is a measure of the layer thickness; (ii) the length of fault trace increases with the amount of downthrow; and (iii) faults tend to form domino domains. Some experiments with a brittle layer on a ductile substrate show a mechanism of passive rifting where; (i) major faults occur in conjugate pairs, defining rift valleys; (ii) minor faults localize additional extension in rift-valley floors; and (iii) isostatic uplift of the viscous substrate causes uplift and tilting of rift rims. In freely floating continents, gravitational spreading leads to: (i) highly localized extension and thinning at continental margins and (ii) internal rifting.
This article has been cited by other articles:
 |
|
 |
|
  L. Mattioni, L. Le Pourhiet, and I. Moretti Rifting through a heterogeneous crust: insights from analogue models and application to the Gulf of Corinth Geological Society, London, Special Publications, 2006; 253: 213 - 231. [Abstract] [PDF]
|
|
|
|
|
|
T. Nalpas, D. Gapais, J. Verges, L. Barrier, V. Gestain, G. Leroux, D. Rouby, and J.-J. Kermarrec Effects of rate and nature of synkinematic sedimentation on the growth of compressive structures constrained by analogue models and field examples Geological Society, London, Special Publications, 2003; 208: 307 - 319. [Abstract] [PDF]
|
|
|
|
|
|
H. Fossen, T. Odinsen, R. B. Faerseth, and R. H. Gabrielsen Detachments and low-angle faults in the northern North Sea rift system Geological Society, London, Special Publications, 2000; 167: 105 - 131. [Abstract] [PDF]
|
|
|
|
|
|
T. Roman-Berdiel, A. Aranguren, J. Cuevas, J. M. Tubia, D. Gapais, and J.-P. Brun Experiments on granite intrusion in transtension Geological Society, London, Special Publications, 2000; 174: 21 - 42. [Abstract] [PDF]
|
|
|
|
|
|
T. Roman-Berdiel Geometry of granite emplacement in the upper crust: contributions of analogue modelling Geological Society, London, Special Publications, 1999; 168: 77 - 94. [Abstract] [PDF]
|
|
|
|
|
|
G. Schreurs and B. Colletta Analogue modelling of faulting in zones of continental transpression and transtension Geological Society, London, Special Publications, 1998; 135: 59 - 79. [Abstract] [PDF]
|
|
|
|
|
|
P. G. Thomas, P. Allemand, and N. Mangold Rheology of planetary lithospheres: a review from impact cratering mechanics Geological Society, London, Special Publications, 1997; 121: 39 - 62. [Abstract] [PDF]
|
|
|
|
|
|
K. R. McClay Recent advances in analogue modelling: uses in section interpretation and validation Geological Society, London, Special Publications, 1996; 99: 201 - 225. [Abstract] [PDF]
|
|
|
|
|
|
M. Verschuren, D. Nieuwland, and J. Gast Multiple detachment levels in thrust tectonics: Sandbox experiments and palinspastic reconstruction Geological Society, London, Special Publications, 1996; 99: 227 - 234. [Abstract] [PDF]
|
|
|
|
|
|
J. D. Van Wees, S. Cloetingh, and G. de Vicente The role of pre-existing faults in basin evolution: constraints from 2D finite element and 3D flexure models Geological Society, London, Special Publications, 1996; 99: 297 - 320. [Abstract] [PDF]
|
|
|
|
|
|
D. Barr Subsidence and sedimentation in semi-starved half-graben: a model based on North Sea data Geological Society, London, Special Publications, 1991; 56: 17 - 28. [Abstract] [PDF]
|
|
