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We used two-dimensional finite element models to explore different configurations of weak layers in undeformed sedimentary sequences to investigate the occurrence of three characteristic types of thrust configurations: ramp-flat; imbricate; and duplex. In our models, we embedded two low-friction weak layers with a finite spatial extent in a sequence of stronger rock. These two weak layers were initially horizontal, were separated vertically by 1 km, and were arranged in three different relative positions to each other. When the models were deformed and these weak layers developed into decollements, they interacted to produce one of the three types of thrust faults as a function of their initial configurations. When the tips of weak layers were separated by a large gap (>10 km), only the lower-level decollement became active, producing imbricate thrusts. When the two weak layers overlapped for a large distance (>10 km), they simultaneously became active decollements, producing duplexes in the overlapped zone. When the gap or overlap was small ( |
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