block diagram of a monoclineThe Grandview-Phantom Monocline in the
Grand Canyon, ArizonaMonocline at
Colorado National MonumentMonocline formed at tip of small thrust fault, Brims Ness,
Caithness, Scotland
A monocline (or, rarely, a monoform) is a step-like
fold in rock
strata consisting of a zone of steeper
dip within an otherwise horizontal or gently dipping sequence.
Formation
Possible modes of formation of monoclines
Monoclines may be formed in several different ways (see diagram)
By differential
compaction over an underlying structure, particularly a large fault at the edge of a
basin due to the greater compactibility of the basin fill, the amplitude of the fold will die out gradually upwards.[1]
By mild reactivation of an earlier
extensional fault during a phase of
inversion causing folding in the overlying sequence.[2]
As a form of fault propagation fold during upward propagation of an extensional fault in basement into an overlying cover sequence.[3]
As a form of fault propagation fold during upward propagation of a
reverse fault in basement into an overlying cover sequence.[4]