Monocline

Amonocline(or, rarely, amonoform) is a step-likefoldin rockstrataconsisting of a zone of steeperdipwithin an otherwise horizontal or gently dipping sequence.

Formation

Monoclines may be formed in several different ways (see diagram)

By differentialcompactionover an underlying structure, particularly a large fault at the edge of abasindue to the greater compactibility of the basin fill, the amplitude of the fold will die out gradually upwards.^[1]
By mild reactivation of an earlierextensional faultduring a phase ofinversioncausing 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 areverse faultin basement into an overlying cover sequence.^[4]

Examples

Waterpocket FoldinCapitol Reef National Park,Utah^[5]
Comb Ridgein southernUtah^[6]
Grandview-Phantom Monocline inGrand Canyon,Arizona^[7]
Grand HogbackinColorado^[8]
Lebombo Mountainsin Southern Africa^[9]
Lapstone Monocline in theBlue Mountains (Australia)^[10]
Beaumaris Monocline inVictoria (Australia)^[11]
Purbeck Monoclineon theIsle of Purbeck,Dorset, England^[12]
Fore-Sudetic Monocline, Poland^[13]
Sindh Monocline,Pakistan^[14]
Torres Flexure, southernBrazil^[15]

References

^Skuce, A.G. (1996)."Forward modelling of compaction above normal faults: an example from the Sirte Basin, Libya"(PDF).In Buchanan, P.G.; Nieuwland, D.A. (eds.).Modern Developments in Structural Interpretation, Validation and Modelling.Special Publications. Vol. 99. London: Geological Society. pp. 135–146.ISBN 978-1-897799-43-7.Archived fromthe original(PDF)on 2012-03-16.
^Chadwick, R.A. (1993)."Aspects of basin inversion in southern Britain".Journal of the Geological Society.150(2): 311–322.Bibcode:1993JGSoc.150..311C.doi:10.1144/gsjgs.150.2.0311.S2CID 131396080.
^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(4): 651–669.Bibcode:2002JSG....24..651W.doi:10.1016/S0191-8141(01)00120-1.Archived fromthe original(PDF)on 2011-07-20.Retrieved2011-01-09.
^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(4): 515–528.Bibcode:2003JSG....25..515F.doi:10.1016/S0191-8141(02)00053-6.
^"Geology".Capitol Reef National Park.National Park Service.23 December 2017.Retrieved1 March2018.
^"Comb Ridge, Utah".earthobservatory.nasa.gov.2019-11-24.Retrieved2021-10-22.
^Abbott, Lon; Cook, Terri (2004).Hiking the Grand Canyon's Geology.Seattle: The Mountaineers Books. pp. 99–114.ISBN 978-0-89886-895-1.
^Murray, Frederick N. (1967). "Jointing in Sedimentary Rocks along the Grand Hogback Monocline, Colorado".The Journal of Geology.75(3): 340–350.Bibcode:1967JG.....75..340M.doi:10.1086/627261.JSTOR 30071521.S2CID 128672429.
^Klausen, M.B. (2009). "The Lebombo monocline and associated feeder dyke swarm: Diagnostic of a successful and highly volcanic rifted margin?".Tectonophysics.468(1–4): 42–62.Bibcode:2009Tectp.468...42K.doi:10.1016/j.tecto.2008.10.012.
^"L001: Lapstone Monocline".Heritage places and items.Office of Environment and Heritage,Government of New South Wales.Retrieved1 March2018.
^"61. Beaumaris Cliffs 3 - Monocline".Sites of Geological and Geomorphological Significance.Agriculture Victoria. 8 June 2017.Retrieved1 March2018.
^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.Bibcode:1997PrGA..108..257N.doi:10.1016/S0016-7878(97)80011-9.
^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.
^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.
^Seth, H. (2018).Tectonic Deformation of Flood Basalt Provinces.Springer.ISBN 978-3-319-67704-0.

[Skuce-1] Skuce, A.G. (1996)."Forward modelling of compaction above normal faults: an example from the Sirte Basin, Libya"(PDF).In Buchanan, P.G.; Nieuwland, D.A. (eds.).Modern Developments in Structural Interpretation, Validation and Modelling.Special Publications. Vol. 99. London: Geological Society. pp. 135–146.ISBN 978-1-897799-43-7.Archived fromthe original(PDF)on 2012-03-16.

[andy-2] Chadwick, R.A. (1993)."Aspects of basin inversion in southern Britain".Journal of the Geological Society.150(2): 311–322.Bibcode:1993JGSoc.150..311C.doi:10.1144/gsjgs.150.2.0311.S2CID 131396080.

[willsey-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(4): 651–669.Bibcode:2002JSG....24..651W.doi:10.1016/S0191-8141(01)00120-1.Archived fromthe original(PDF)on 2011-07-20.Retrieved2011-01-09.

[finch-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(4): 515–528.Bibcode:2003JSG....25..515F.doi:10.1016/S0191-8141(02)00053-6.

[NPSCapitol-5] "Geology".Capitol Reef National Park.National Park Service.23 December 2017.Retrieved1 March2018.

[6] "Comb Ridge, Utah".earthobservatory.nasa.gov.2019-11-24.Retrieved2021-10-22.

[7] Abbott, Lon; Cook, Terri (2004).Hiking the Grand Canyon's Geology.Seattle: The Mountaineers Books. pp. 99–114.ISBN 978-0-89886-895-1.

[Murray1967-8] Murray, Frederick N. (1967). "Jointing in Sedimentary Rocks along the Grand Hogback Monocline, Colorado".The Journal of Geology.75(3): 340–350.Bibcode:1967JG.....75..340M.doi:10.1086/627261.JSTOR 30071521.S2CID 128672429.

[Klausen2009-9] Klausen, M.B. (2009). "The Lebombo monocline and associated feeder dyke swarm: Diagnostic of a successful and highly volcanic rifted margin?".Tectonophysics.468(1–4): 42–62.Bibcode:2009Tectp.468...42K.doi:10.1016/j.tecto.2008.10.012.

[NSW_Gov-10] "L001: Lapstone Monocline".Heritage places and items.Office of Environment and Heritage,Government of New South Wales.Retrieved1 March2018.

[VRO1-11] "61. Beaumaris Cliffs 3 - Monocline".Sites of Geological and Geomorphological Significance.Agriculture Victoria. 8 June 2017.Retrieved1 March2018.

[Nowell1997-12] 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.Bibcode:1997PrGA..108..257N.doi:10.1016/S0016-7878(97)80011-9.

[KluskaEtAl2013-13] 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.

[MemonEtAl1999-14] 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.

[Seth1-15] Seth, H. (2018).Tectonic Deformation of Flood Basalt Provinces.Springer.ISBN 978-3-319-67704-0.

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v t e Structural geology
Underlying theory	Deformation mechanism Lamé's stress ellipsoid Mohr–Coulomb theory Mohr's circle Overburden pressure Rock mechanics Strain Strain partitioning Stress Stress field Tension
Measurement conventions	Brunton compass Inclinometer Orthographic projection Rake Stereographic projection Strike and dip
Large-scaletectonics	Accretionary wedge Allochthon Autochthon Back-arc basin Continental collision Convergent boundary Décollement Divergent boundary Extensional tectonics Fault block Fenster Fold and thrust belt Fold mountains Foreland basin Graben Half-graben Horse Horst Horst and graben Intra-arc basin Inversion Klippe List of tectonic plate interactions Mélange Mountain formation Nappe Obduction Orogeny Passive margin Plate tectonics Pull-apart basin Rift valley Rift Saddle Strike-slip tectonics Structural basin Suture Syneclise Terrane Thick-skinned deformation Thin-skinned deformation Thrust tectonics
Fracturing	Columnar jointing Dike Exfoliation joint Fissure Joint Vein
Faulting	Cataclasite Cataclastic rock Detachment fault Disturbance Fault mechanics Fault scarp Fault trace Thrust fault Transfer zone Transform fault
Foliationandlineation	Cleavage Compaction Crenulation Fissility Oblique foliation Pressure solution Rock microstructure Slickenside Stylolite Tectonic phase Tectonite
Folding	Anticline Chevron Detachment fold Dome Homocline Monocline Syncline Vergence
Boudinage	Competence
Kinematic analysis	3D fold evolution Paleostress inversion Paleostress Section restoration
Shear zone	Mylonite Pure shear Shear
Category

Formation

Examples

See also

References