--> Abstract: The Effect of Cover Strength on Extensional Fault Propagation, by Emma Finch, Rob Gawthorpe, and Stuart Hardy; #90039 (2005)
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The Effect of Cover Strength on Extensional Previous HitFaultNext Hit Propagation

Emma Finch1, Rob Gawthorpe1, and Stuart Hardy2
1 Manchester University, Manchester, United Kingdom
2 Universitat de Barcelona, 08028 Barcelona, Spain

A discrete element technique has been developed to investigate the effect of cover strength on the propagation of blind normal faults of varying dip. Slip on the basement Previous HitfaultNext Hit is initially observed through the growth of an upward-widening monocline in the cover where the width of the monocline increases as Previous HitfaultNext Hit dip decreases. Increased slip results in the monocline being breached by a single, through-going structure, where strain localises onto a single Previous HitfaultNext Hit producing hangingwall synclines and footwall anticlines. Previous HitFaultNext Hit propagation and folding in the cover are also strongly controlled by the strength of the overburden material. A reduction in the strength of the cover results in: a) the width of the monocline above the Previous HitfaultNext Hit tip increasing, b) more noticeable footwall thinning and hangingwall thickening of beds and c) a reduction of the rate of Previous HitfaultNext Hit propagation into the cover. Structures observed from multi-layer experiments demonstrate that the more competent layers dominate basement Previous HitfaultNext Hit propagation through the overburden, producing complex structural relationships. Faults develop along layer boundaries and are not necessarily linked to the basement Previous HitfaultNext Hit at depth. Inclusion of syn-tectonic sedimentation results in a marked difference in both the rate and style of Previous HitfaultNext Hit propagation. As sedimentation rates are increased the time to develop a single through-going structure increases and an increase in the coherence of the sediment reduces the rate of Previous HitfaultTop propagation.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005