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- Title
The Interrelationship of Micro-Meso and Macroscopic Structures on the Western Limb of the Hazara Kashmir Syntaxis, Pakistan.
- Authors
AHMAD, Sohaib; ALI, Asghar; REHMAN, Khaista
- Abstract
Detailed micro-meso to macroscopic structural analyses reveal two deformation phases in the western limb of the Hazara-Kashmir Syntaxis (HKS). Bulk top to NW shearing transformed initially symmetrical NNE-SSW trending meso to macroscopic folds from asymmetric to overturned ones without changing their trend. Sigmoidal en-echelon tension gashes developed during this deformation, that were oblique to bedding parallel worm burrows and bedding planes themselves. Strain analyses of deformed elliptical ooids using the Rf/ϕ method constrain the internal strain patterns of the NNE-SSW structures. The principal stretching axis (S3) defined by deformed elliptical ooids is oriented N27°E at right angles to WNW-ESE shortening. The deformed elliptical ooids in sub-vertical bedding vertical planes contain ooids that plunge ∼70° SE due to NW-directed tectonic transport. Finite strain ratios are 1.45 ( Rxy) parallel to bedding plane and 1.46 ( Ryz) for the vertical plane. From these 2D strain values, we derive an oblate strain ellipsoidal in 3D using the Flinn and Hsu/Nadai techniques. Strains calculated from deformed elliptical ooids average −18.10% parallel to bedding and −18.47% in the vertical plane. However, a balanced cross-section through the study area indicates a minimum of ∼ −28% shortening. Consequently, regional shortening was only partially accommodated by internal deformation.
- Subjects
PAKISTAN; STRUCTURAL geology; STRAIN hardening; ROCK deformation; STRAINS &; stresses (Mechanics)
- Publication
Acta Geologica Sinica (English Edition), 2017, Vol 91, Issue 5, p1573
- ISSN
1000-9515
- Publication type
Article
- DOI
10.1111/1755-6724.13401