Monocline

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block diagram of a monocline
The Grandview-Phantom Monocline in the Grand Canyon, Arizona
Monocline 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[edit]

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]

Examples[edit]

See also[edit]

References[edit]

  1. ^ Skuce, A.G. (1996). "Forward modelling of compaction above normal faults: an example from the Sirte Basin, Libya". In Buchanan,P.G.; Nieuwland,D.A. Modern Developments in Structural Interpretation, Validation and Modelling (PDF). Special Publications. 99. London: Geological Society. pp. 135–146. ISBN 978-1-897799-43-7. Archived from the original (PDF) on 2012-03-16. 
  2. ^ Chadwick, R.A. (1993). "Aspects of basin inversion in southern Britain". Journal of the Geological Society. 150: 311–322. Bibcode:1993JGSoc.150..311C. doi:10.1144/gsjgs.150.2.0311. 
  3. ^ Willsey, S.P.; Umhoefer,P.J.; Hilley,G.E. (2002). "Early evolution of an extensional monocline by a propagating normal fault: 3D analysis from combined field study and numerical modeling" (PDF). Journal of Structural Geology. 24: 651–669. Bibcode:2002JSG....24..651W. doi:10.1016/S0191-8141(01)00120-1. 
  4. ^ Finch, E.; Hardy,S.; Gawthorpe,R. (2003). "Discrete element modelling of contractional fault-propagation folding above rigid basement fault blocks". Journal of Structural Geology. 25: 515–528. Bibcode:2003JSG....25..515F. doi:10.1016/S0191-8141(02)00053-6. 
  5. ^ "Geology". Capitol Reef National Park. National Park Service. 23 December 2017. Retrieved 1 March 2018. 
  6. ^ Abbott, Lon and Cook, Terri (2004). Hiking the Grand Canyon's Geology. Seattle: The Mountaineers Books. pp. 99–114. ISBN 0-89886-895-5. 
  7. ^ Murray, Frederick N. (1967). "Jointing in Sedimentary Rocks along the Grand Hogback Monocline, Colorado". The Journal of Geology. 75 (3): 340–350. JSTOR 30071521. 
  8. ^ Klausen, M.B. (2009). "The Lebombo monocline and associated feeder dyke swarm: Diagnostic of a successful and highly volcanic rifted margin?". Tectonophysics. 468: 42–62. Bibcode:2009Tectp.468...42K. doi:10.1016/j.tecto.2008.10.012. 
  9. ^ "L001 : Lapstone Monocline". Heritage places and items. Office of Environment and Heritage, Government of New South Wales. Retrieved 1 March 2018. 
  10. ^ "61. Beaumaris Cliffs 3 - Monocline". Sites of Geological and Geomorphological Significance. Agriculture Victoria. 8 June 2017. Retrieved 1 March 2018. 
  11. ^ Nowell, D.A.G. (1997). "Structures affecting the coast around Lulworth Cove, Dorset and syn-sedimentary Wealden faulting". Proceedings of the Geologists' Association. 108 (4): 257–268. doi:10.1016/S0016-7878(97)80011-9. 
  12. ^ Kluska, B.; Rospondek, M.J.; Marynowski, L.; Schaeffer, P. (2013). "The Werra cyclotheme (Upper Permian, Fore-Sudetic Monocline, Poland): Insights into fluctuations of the sedimentary environment from organic geochemical studies". Applied Geochemistry. 29: 73–91. Bibcode:2013ApGC...29...73K. doi:10.1016/j.apgeochem.2012.09.010. 
  13. ^ Memon, A.D.; Siddiqui, I.; Memon, A. (1999). "Tectonics of the Sindh monocline, Pakistan and their effects on hydrocarbons". Mehran University Research Journal of Engineering and Technology. 18 (2): 87–96. 
  14. ^ Seth, H. (2018). Tectonic Deformation of Flood Basalt Provinces. Springer. ISBN 978-3-319-67704-0. 

External links[edit]