Monocline

block diagram of a monocline

A monocline is a step-like fold consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence.

possible modes of formation of monoclines

[edit] Formation

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 e.g. ^[1]

By mild reactivation of an earlier extensional fault during a phase of inversion causing folding in the overlying sequence e.g. ^[2]

As a form of fault propagation fold during upward propagation of an extensional fault in basement into an overlying cover sequence e.g. ^[3]

As a form of fault propagation fold during upward propagation of a reverse fault in basement into an overlying cover sequence e.g. ^[4]

^ Skuce,A.G. 1996. Forward modelling of compaction above normal faults: an example from the Sirtse Basin, Libya. In: Buchanan,P.G. and Nieuwland,D.A. (eds)Geological Society Special Publication, 99, 135-146.
^ Chadwick,R.A. 1993. Aspects of basin inversion in southern Britain. Journal of the Geological Society, 150, 311-322.
^ Willsey,S.P., Umhoefer,P.J. and Hilley,G.E. 2002. Early evolution of an extensional monocline by a propagating normal fault: 3D analysis from combined field study and numerical modeling.Journal of Structural Geology, 24, 651-669.
^ Finch,E., Hardy,S. and Gawthorpe,R.2003. Discrete element modelling of contractional fault-propagation folding above rigid basement fault blocks. Journal of Structural Geology, 25, 515-528.