Simple constructions for deformation in transpression/transtension zones

McCoss, Angus

doi:10.1016/0191-8141(86)90077-5

Cited by 91 publications

(33 citation statements)

References 3 publications

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“…Mineral-filled veins and joints or open fractures are commonly mode I (extension) fractures. According to McCoss (1986), veins usually form as en echelon segment in any array indicating a component of shear. A joint is any thin planar fracture that is not a fault, bedding or cleavage surface (Suppe, 1985).…”

Section: Brief Review Of Fracture Terminologymentioning

confidence: 99%

The Fadnoun area, Tassili-n-Azdjer, Algeria: Fracture network geometry analysis

Zazoun

2008

Journal of African Earth Sciences

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Section: Brief Review Of Fracture Terminologymentioning

confidence: 99%

The Fadnoun area, Tassili-n-Azdjer, Algeria: Fracture network geometry analysis

Zazoun

2008

Journal of African Earth Sciences

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“…Possible field examples of such switching behaviour have been described by Hudleston et al (1988), Holdsworth (1989) and Tikoff & Greene (1997). Conversely, in transtension, the stretching direction is always horizontal, but the shortening direction switches from vertical to horizontal where ct < 20 ~ with increasing finite strain (McCoss 1986). Thus, if no kinematic partitioning occurs, any planar fabric switches from vertical to horizontal with increasing strain or vice versa if boundary-parallel wrench simple sheardominated high-strain zones form as a result of partitioning.…”

Section: Fabric Patterns and Structural Stylementioning

confidence: 99%

“…Fig. 6a -f;McCoss 1986;Fossen & Tikoff 1993;Fossen et al 1994;Tikoff & Teyssier 1994;Tikoff & Greene 1997). In monoclinic transpression zones where the bulk deformation follows the vertical stretch model of Sanderson & Marchini (1984), the strikes of the principal flattening surface (cleavage, schistosity, gneissosity) will vary with the non-coaxial component of the strain (Fig.…”

Section: Fabric Patterns and Structural Stylementioning

confidence: 99%

Transpression and transtension zones

1998

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Transpression and transtension are strike-slip deformations that deviate from simple shear because of a component of, respectively, shortening or extension orthogonal to the deformation zone. These three-dimensional non-coaxial strains develop principally in response to obliquely convergent or divergent relative motions across plate boundary and other crustal deformation zones at various scales. The basic constant-volume strain model with a vertical stretch can be modified to allow for volume change, lateral stretch, an oblique simple shear component, heterogeneous strain and steady-state transpression and transtension. The more sophisticated triclinic models may be more realistic but their mathematical complexity may limit their general application when interpreting geological examples. Most transpression zones generate flattening (k < 1) and transtension zones constrictional (k > 1) finite strains, although exceptions can occur in certain situations. Relative plate motion vectors, instantaneous strain (or stress) axes and finite strain axes are all oblique to one another in transpression and transtension zones. Kinematic partitioning of non-coaxial strike-slip and coaxial strains appears to be a characteristic feature of many such zones, especially where the far-field (plate) displacement direction is markedly oblique (<20 ~ to the plate or deformation zone boundary. Complex foliation, lineation and other structural patterns are also expected in such settings, resulting from switching or progressive rotation of finite strain axes. The variation in style and kinematic linkage of transpressional and transtensional structures at different crustal depths is poorly understood at present but may be of central importance to understanding the relationship between deformation in the lithospheric mantle and crust. Existing analyses of obliquely convergent and divergent zones highlight the importance of kinematic boundary conditions and imply that stress may be of secondary importance in controlling the dynamics of deformation in the crust and lithosphere.

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“…To determine the orientation of the principal axis of strain of the incremental strain ellipsoid, we use the geometrically simple construction proposed by McCoss (1986). We analyze the results in relation to the kinematics of finite structures observed in the field and discuss the structural data in view of geochronological SASZ data, as well as data obtained from models of extensional deformation in orogenic belts, with particular emphasis on the spatial and temporal relationship between extensional and compressional strain.…”

Section: Introductionmentioning

confidence: 99%