Information on the incremental strain history may be obtained from the analysis of the final strain configuration in a heterogeneous shear zone. In particular, in case the structural evolution was characterized by strain softening or hardening – which are assumed to control the development of localizing and delocalizing shear zones, respectively – one can unravel the relationship between finite strain across the shear zone and incremental strains. Based on this assumption, an inverse method was derived which is able to evaluate the incremental strain matrices starting from measured finite strain quantities in a heterogeneous ductile shear zone. The proposed technique uses the finite values of the effective shear strain Γ and the finite angle θ’ (angle between the foliation, i.e. the xy plane of the finite strain ellipsoid, and the shear plane) obtained for n layers, in which a shear zone may be subdivided according to homogeneity criteria. Shear zone deformation may then be described in terms of n finite strain matrices, each representing homogeneous deformation of the related layer. Starting from these matrices, it is possible to derive the incremental strain matrices. For simple cases, the proposed method furnishes symbolic formulae relating finite and incremental values of the main strain parameters, such as shear strain and stretches. The inverse method requires knowing the strain parameters k1, k2, k3, and Γ. In particular instances such as that analyzed in this paper, it is possible to derive all of the required strain parameters from simple formulae. For the analyzed wrench zone, characterized by no stretches along the x direction and no volume change, the incremental strain path suggests a localizing shear zone evolution characterized by an initial homogeneous transtensional deformation in the whole shear zone and a subsequent incremental transpression driven by strain softening processes affecting progressively inner sectors.

From finite to incremental strain: Insights into heterogeneous shear zone evolution / Vitale, Stefano; Mazzoli, Stefano. - (2015), pp. 3-13. [10.1002/9781118844953.ch1]

From finite to incremental strain: Insights into heterogeneous shear zone evolution

VITALE, STEFANO;MAZZOLI, STEFANO
2015

Abstract

Information on the incremental strain history may be obtained from the analysis of the final strain configuration in a heterogeneous shear zone. In particular, in case the structural evolution was characterized by strain softening or hardening – which are assumed to control the development of localizing and delocalizing shear zones, respectively – one can unravel the relationship between finite strain across the shear zone and incremental strains. Based on this assumption, an inverse method was derived which is able to evaluate the incremental strain matrices starting from measured finite strain quantities in a heterogeneous ductile shear zone. The proposed technique uses the finite values of the effective shear strain Γ and the finite angle θ’ (angle between the foliation, i.e. the xy plane of the finite strain ellipsoid, and the shear plane) obtained for n layers, in which a shear zone may be subdivided according to homogeneity criteria. Shear zone deformation may then be described in terms of n finite strain matrices, each representing homogeneous deformation of the related layer. Starting from these matrices, it is possible to derive the incremental strain matrices. For simple cases, the proposed method furnishes symbolic formulae relating finite and incremental values of the main strain parameters, such as shear strain and stretches. The inverse method requires knowing the strain parameters k1, k2, k3, and Γ. In particular instances such as that analyzed in this paper, it is possible to derive all of the required strain parameters from simple formulae. For the analyzed wrench zone, characterized by no stretches along the x direction and no volume change, the incremental strain path suggests a localizing shear zone evolution characterized by an initial homogeneous transtensional deformation in the whole shear zone and a subsequent incremental transpression driven by strain softening processes affecting progressively inner sectors.
2015
9781118844953
9781118844960
9781118844953
9781118844960
From finite to incremental strain: Insights into heterogeneous shear zone evolution / Vitale, Stefano; Mazzoli, Stefano. - (2015), pp. 3-13. [10.1002/9781118844953.ch1]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/630318
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