TY - JOUR

T1 - Anisotropic viscosity of a dispersion of aligned elliptical cylindrical clasts in viscous matrix

AU - Fletcher, Raymond C.

N1 - Funding Information:
The solution to the auxiliary problem was completed during postdoctoral work supported by National Science Foundation grant GA-12947 to Barclay Kamb. Work related to anisotropic composites is also supported by NSF OPP-9815160. The National Science Foundation bears no responsibility for the contents of this paper. My more recent interest in the behavior and evolution of composite materials has been stimulated by reading the papers of and e-mail correspondence with Sue Treagus. Labao Lan is thanked for a useful review.
Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

PY - 2004/11

Y1 - 2004/11

N2 - Self-consistent averaging, using an auxiliary solution for an elliptical anisotropic viscous inclusion in an anisotropic viscous host, provides estimates of the principal bulk viscosities of a dispersion of aligned elliptical viscous clasts in an isotropic or anisotropic viscous matrix. Analysis and results are for a two-dimensional analog of a composite rock with clasts that are cylinders with axes normal to the plane of flow. The ratio of principal viscosities, ηn in clast parallel extension or shortening, ηs in clast-parallel shear, m = ηn/ηs, is smaller than that obtained using an auxiliary solution in which the host is isotropic. Results for the limiting case of rigid clasts indicates that the latter procedure overestimates the stress concentration in axis-parallel extension or shortening at intermediate clast volume fraction, f. If the matrix is anisotropic, bulk anisotropy derives from both the shape anisotropy and the intrinsic anisotropy of the matrix, and unsymmetrical relations for the principal viscosities and m (f) result. The results suggest that rheological anisotropy in rocks with a planar fabric is greatly reduced if the components are lenticular in form rather than continuous layers. A general solution is given for an elliptical inclusion for the case that the principal axes of anisotropy in both the host and the inclusion are oblique to the axes of the elliptical section and the host is subjected to homogeneous stress far from the inclusion.

AB - Self-consistent averaging, using an auxiliary solution for an elliptical anisotropic viscous inclusion in an anisotropic viscous host, provides estimates of the principal bulk viscosities of a dispersion of aligned elliptical viscous clasts in an isotropic or anisotropic viscous matrix. Analysis and results are for a two-dimensional analog of a composite rock with clasts that are cylinders with axes normal to the plane of flow. The ratio of principal viscosities, ηn in clast parallel extension or shortening, ηs in clast-parallel shear, m = ηn/ηs, is smaller than that obtained using an auxiliary solution in which the host is isotropic. Results for the limiting case of rigid clasts indicates that the latter procedure overestimates the stress concentration in axis-parallel extension or shortening at intermediate clast volume fraction, f. If the matrix is anisotropic, bulk anisotropy derives from both the shape anisotropy and the intrinsic anisotropy of the matrix, and unsymmetrical relations for the principal viscosities and m (f) result. The results suggest that rheological anisotropy in rocks with a planar fabric is greatly reduced if the components are lenticular in form rather than continuous layers. A general solution is given for an elliptical inclusion for the case that the principal axes of anisotropy in both the host and the inclusion are oblique to the axes of the elliptical section and the host is subjected to homogeneous stress far from the inclusion.

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U2 - 10.1016/j.jsg.2004.04.004

DO - 10.1016/j.jsg.2004.04.004

M3 - Article

AN - SCOPUS:13944257810

SN - 0191-8141

VL - 26

SP - 1977

EP - 1987

JO - Journal of Structural Geology

JF - Journal of Structural Geology

IS - 11

ER -