Map-view interference of monoclinal folds

Outcrop observations and laboratory experiments show that many small chevron folds form by interference of monoclinal kink bands in multilayer buckling. Kink-band interference has also been proposed for some map-scale folds. Furthermore, fault-related folding provides additional mechanisms of monoclinal fold generation, other than buckling, and thus makes kink-band interference all the more conceptually plausible as a significant large-scale process. In this paper we document several relatively simple examples of map-scale monoclinal fold interference, including three interfering monoclines of the Colorado Plateau, a seismically-imaged example in the Perdido foldbelt of the Gulf of Mexico, and a more complex example from seismic mapping in the Santa Barbara Channel, California. Kink-band interference has normally been analyzed in cross section. Here we emphasize the map-view phenomena and present a simple balanced three-dimensional model of the interference geometry, treating the monoclines as two independent kink bands, which does not depend of the kink-band folding mechanism. This model predicts the shape of the jog produced by crossing monoclines and is used to help evaluate the role of interference in the map-view geometry of our examples. The documentation of these simple examples supports the concept that more complex monoclinal fold interference could be a significant phenomenon in the upper crust.