Testing The Influence of Brittle-viscous Multilayers On Faulting During Rifting In Analogue Models
Abstract
Analogue model experiments analyzed by computerized tomography (CT) were per- formed to test the influence of brittle-viscous multilayers on faulting during rifting. In each experiment a lower viscous layer was placed over the entire base of the model, whereas a second upper viscous layer separated lower brittle materials from upper brittle strata. Parameters such as thickness, lateral changes and position of viscous layers had a profound influence on the style of extensional structures. The presence of two viscous layers interbedded at different levels within the brittle layers resulted in the development of two independent, decoupled conjugate fault systems in upper and lower brittle strata. Width between conjugate faults reflects the depth to the viscous layer. With increasing extension, synthetic normal faults (dipping towards the extend- ing mobile wall) in the lower brittle strata became preferentially active and fault blocks rotated about horizontal axes. Rotations of these fault blocks and accompanied lateral viscous flow caused additional fault development U locally with a reverse slip com-
ponent - in upper brittle strata. Continued extension eventually led to local linkage between faults in lower and upper brittle strata. Lateral termination of the upper vis- cous layer resulted in the development of extensional transfer zones in surface view and in horizontal sections at depth. Location and orientation of these transfer zones are directly linked to the geometry of the upper viscous layer. Where the initial bound- ary of the upper viscous layer was parallel to the extension direction, the strike of the transfer zone was also parallel. Where this boundary was oblique, the transfer zone also formed oblique.- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.5255S