Horse (geology)

Diagram showing development of thrust-bounded horses within a thrust duplex

A horse sits between the walls of this normal fault located near Upheaval Dome, Utah. The fault plane traces from the upper right to the lower left of the image. The horse is the broad lens-shaped feature in the rock defined by the splitting and rejoining of the trace of the fault plane. Some boudinage due to shearing is visible within the horse.

Horse is the geological technical term used for any block of rock completely separated from the surrounding rock either by mineral veins or fault planes. In mining the term refers to a block of country rock entirely encased within a mineral lode.^[1] In structural geology the term was first used to describe the thrust-bounded imbricates found within a thrust duplex.^[2] In later literature it has become a general term for any block entirely bounded by faults, whether the overall deformation type is contractional, extensional or strike-slip in nature.^[3]^[4]

References[]

^ Butler, F.H. 1911. The brecciation of mineral veins.
^ Dennis, J.G. 1967. International tectonic dictionary. AAPG Memoir 7, 196pp.
^ Root, K.G. 1990. Extensional duplex in the Purcell Mountains of southeastern British Columbia. Geology, 18, 419-421
^ Laney, Stephen E; Gates, Alexander E (1996), "Three-dimensional shuffling of horses in a strike-slip duplex: an example from the Lambertville sill, New Jersey", Tectonophysics, 258 (1–4): 53–70, doi:10.1016/0040-1951(95)00173-5

External links[]

"Horse. A miner's term" . New International Encyclopedia. 1905.

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[1] Butler, F.H. 1911. The brecciation of mineral veins.

[2] Dennis, J.G. 1967. International tectonic dictionary. AAPG Memoir 7, 196pp.

[3] Root, K.G. 1990. Extensional duplex in the Purcell Mountains of southeastern British Columbia. Geology, 18, 419-421

[4] Laney, Stephen E; Gates, Alexander E (1996), "Three-dimensional shuffling of horses in a strike-slip duplex: an example from the Lambertville sill, New Jersey", Tectonophysics, 258 (1–4): 53–70, doi:10.1016/0040-1951(95)00173-5

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v t 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-scale tectonics	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
Foliation and lineation	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
	3D fold evolution Paleostress inversion Paleostress Section restoration
Shear zone	Mylonite Pure shear Shear