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Strain and kinematics within the Salmon River suture zone and western Idaho shear zone, Idaho, USA: Exploring the contribution of ductile stretching to mass transfer and exhumation in fold-thrust and transpressional systems.
- Source :
-
Journal of Structural Geology . Sep2024, Vol. 186, pN.PAG-N.PAG. 1p. - Publication Year :
- 2024
-
Abstract
- Measuring penetrative strain is critical for understanding the 3D strain field of structural systems. Here, we investigate ductile strain and kinematics in two Cordilleran structural systems in north-central Idaho: the Salmon River suture zone (SRSZ), which is a west-vergent ductile fold-thrust system that accommodated shortening associated with terrane collision between ∼144 and 105 Ma, and the north-striking, subvertical western Idaho shear zone (WISZ), which accommodated dextral-transpressional shearing between ∼105 and 86 Ma. We collected finite strain data from stretched clasts in three SRSZ thrust sheets, which define 56–87% average thrust-parallel stretching and 35–48% average thrust-normal thinning. Thrust-parallel stretching contributed >27 km of cumulative displacement to the up-dip portion of the fold-thrust system, comparable to the 34 km of total thrust displacement estimated at down-dip levels. In the WISZ, we documented dextral kinematics in lineation-normal planes, and we measured boudinaged and folded granitic dikes to estimate late-stage (∼91-86 Ma) strain, which yielded 65% minimum lineation-parallel stretching and 50% minimum east-west shortening. Subvertical stretching in the WISZ accommodated >9–10 km of exhumation relative to the Idaho batholith to the east. The SRSZ and WISZ both demonstrate the 1st-order importance of ductile stretching for accommodating the large-scale transfer of mass and exhumation in fold-thrust and transpressional systems. • Penetrative strain is a critical component of the 3D strain field in thrust systems. • Thrust-parallel stretching can greatly increase displacement in thrust systems. • Thrust-parallel stretching and thrust-normal thinning enhance exhumation. • Lineation-parallel stretching drives exhumation in transpressional shear zones. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01918141
- Volume :
- 186
- Database :
- Academic Search Index
- Journal :
- Journal of Structural Geology
- Publication Type :
- Academic Journal
- Accession number :
- 178941566
- Full Text :
- https://doi.org/10.1016/j.jsg.2024.105216