Abstract

Wrinkle ridges (linear, asymmetric topographic highs) are common physiographic features on the Moon, Mars, and Mercury. We describe here some terrestrial features of similar morphology and scale that have formed under compressional stress systems similar to planetary wrinkle ridges. All of the terrestrial analogs are produced by the anticlinal folding of rocks above reverse faults that shallow and typically break the surface. Characteristics common to both terrestrial and planetary ridges include (1) a linear, asymmetric antiformal shape; (2) tension cracks and grabens along the hinges of the antiform; (3) overlapping, en echelon lobes; (4) reversals of the sense of asymmetry along strike; (5) occurrence in compressional environments; and (6) similarity to features produced during compression of various materials in laboratory scale models. These similarities strongly suggest that planetary wrinkle ridges result from deformation associated with shallow thrust faults that either break or come close to the surface. Kinematic models capable of explaining the development of wrinkle ridges include (1) anticlinal folding of rocks over a buried thrust fault that may subsequently propagate to the surface and (2) fault-bend folding of upper-plate rocks over the surface-flattening bend of a thrust fault.

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