Stretching lineations in transpressional shear zones: an example from the Sierra Nevada Batholith, California

doi:10.1016/S0191-8141(96)00056-9

Journal of Structural Geology

Volume 19, Issue 1, January 1997, Pages 29-39

https://doi.org/10.1016/S0191-8141(96)00056-9 Get rights and content

Abstract

Ductile shear zones and associated stretching lineations are generally considered to be the result of two-dimensional, simple shear deformations, with stretching lineations interpreted to rotate into parallelism with the direction of tectonic transport with increasing deformation. However, stretching lineations perpendicular to the inferred tectonic transport direction are displayed by some shear zones. Field studies in the Sierra Nevada batholith have revealed a single shear zone (the Rosy Finch-Gem Lake shear zone) that contains both steeply-plunging stretching lineations in older metamorphosed sedimentary and granitic rocks, and shallowly-plunging stretching lineations in syntectonic granitoids. Dextral sense-of-shear indicators are found in all these units and deformation occurred simultaneously along the length of the shear zone.

Theoretical strain modeling indicates that stretching lineations can be either horizontal or vertical within transpressional shear zones. To investigate the kinematics of three-dimensional deformation, we examine the role of stretching lineations which form as a result of finite strain, including the possibility of partitioning a component of the strike-slip movement onto shear bands. Comparing the field data with the strain modeling, we interpret the along-strike variation in lineation behavior within the Rosy Finch-Gem Lake shear zone to be a result of the differences in finite strain recorded by different units. The older units, showing steeply-plunging lineation, have recorded more finite strain across a narrower shear zone than the syntectonic granites which record shallowly-plunging lineations. We conclude that the orientation of the lineation within transpressional shear zones does not necessarily correlate with the transport direction, but may reflect along-strike variations in finite strain and/or strain partitioning.

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Citation Excerpt :
However, the ubiquity of shear bands and a-type flanking folds and the general lack of s-type flanking folds with geometries typical for transtension (e.g., Fig. 12a and b) in natural ductile shear zones raises some questions about the occurrence of transtensional shear. In fact, there are numerous examples of ductile shear zones from various tectonic settings for which quantitative strain analysis indicates transpressional flow (Talbot and Sokoutis, 1995; Tikoff and Green, 1997; Grasemann et al., 1999; Lin and Jiang, 2001; Czeck and Hudleston, 2003; Xypolias et al., 2003, 2018; Sengupta and Ghosh, 2004; Goscombe et al., 2005; Passchier et al., 2007; Sullivan and Law, 2007; Sarkarinejad et al., 2008; Gillam et al., 2013; Little et al., 2016; Carreras and Druguet, 2019). In contrast, transtensional flow in ductile shear zones is rarely deduced and typically supported by conceptual models derived from independent geological arguments (Krabbendam and Dewey, 1998; Whitney et al., 2007; Erkül et al., 2017).
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Stretching lineations in transpressional shear zones: an example from the Sierra Nevada Batholith, California

Abstract

Journal of Structural Geology

Tectonophysics

Journal of Structural Geology

Journal of Structural Geology

Tectonophysics

Journal of Structural Geology

Journal of Structural Geology

Journal of Structural Geology

Contrasts in the response to dextral transpression across the Quetico-Wawa subprovince boundary in northeastern Minnesota

Canadian Journal of Earth Science

Stretching lineation and transport direction in the Ibero-Amorican arc during the Siluro-Devonian collision

Geodynamica Acta

Lineation—a critical review and annotated bibliography

Geological Society, America Memoirs

Transpression: Anisotropy of magnetic susceptibility and fabric analysis in granitoids: the Cascade Lake shear zone, Sierra Nevada, California

Dextral shearing in the Cascade Lake shear zone, Tuolumne Intrusive Suite, Sierra Nevada, California

Orogen-parallel extension and oblique tectonics: The relation between stretching lineations and relative plate motions

Geology

The deformation matrix for simultaneous pure shear, simple shear, and volume change, and its application to transpression/trantension tectonics

Journal of Structural Geology

Strain modeling of transpressional and transtensional deformation

Norsk geologisk Tidsskrift

The stratigraphy, structure, and regional tectonic significance of the Northern Ritter Range pendant, eastern Sierra Nevada, California

The Gem Lake shear zone: Cretaceous dextral transpression in the northern Ritter Range pendant, eastern Sierra Nevada, California

Tectonics