Abstract - The growth of normal faults in periodically layered sequences with varying strength
contrast and at varying confining pressure is modeled using the distinct element method.
The normal faulting models are composed of strong layers (bonded particles) and
weak layers (nonbonded particles) that are deformed using a predefined fault at the base
of the sequence. The model results suggest that faults in sequences with high strength
contrast at low confining pressure are highly segmented because of different types of
failure (extension versus shear failure) in the different layers. The degree of segmentation
decreases as the strength contrast decreases and confining pressure increases. Faults at low
confining pressure localize as extension (mode I) fractures within the strong layers and are
later linked via shallow dipping faults in the weak ones. This leads to initial staircase
geometries that, with increasing displacement, cause space problems that are later resolved
by splaying and segmentation. As confining pressure increases, the modeled faults show a
transition from extension to hybrid to shear fracture and an associated decrease in fault
refraction, with a consequent decrease in fault surface irregularities. Therefore the mode of
fracture which is active in the strong layers of a mechanical multilayer at a particular
confining pressure exerts an important control on the final fault geometry.
Journal of Geophysical Research 112, B10404, 2007.