TY - JOUR
KW - Calcite deformation
KW - Deformation mechanism maps
KW - Feldspar deformation
KW - Geometrically necessary deformation mechanisms
KW - Microstructure topology
KW - Relative strengths
KW - Rheology of mixed mechanisms
AU - Stanislav Ulrich
AU - Bruce Hobbs
AU - Alison Ord
AU - Karel Schulmann
AB - The relative strengths of constituent minerals in a deforming poly-mineralic rock depend on the grain size distributions of the various phases, the operating deformation mechanisms in those phases, and the topology of the microstructure. It is observed that more than one deformation mechanism operates, and the resulting constitutive relations (especially for calcite) are extremely variable. To explore such relations, deformation mechanism maps for each mineral are required together with mixing relations for multiple deformation mechanisms. We construct reference deformation mechanism maps for calcite and alkali-feldspars that are based on theoretical expressions for constitutive relations, together with experimental or molecular dynamic estimates of constitutive parameters. A thermodynamically based mixing relation is employed that enables bulk constitutive relations to be established for mixtures of mineral phases and deformation mechanisms with a range of grain sizes. This provides a basis for comparison and understanding of experimental results. We map out fields on deformation mechanism maps where switches in the relative strengths of calcite and quartz and of feldspar and quartz occur. We introduce the concept of geometrically necessary deformation mechanisms that minimise the energy of the system.
BT - Journal of Structural Geology
DO - https://doi.org/10.1016/j.jsg.2020.104056
N2 - The relative strengths of constituent minerals in a deforming poly-mineralic rock depend on the grain size distributions of the various phases, the operating deformation mechanisms in those phases, and the topology of the microstructure. It is observed that more than one deformation mechanism operates, and the resulting constitutive relations (especially for calcite) are extremely variable. To explore such relations, deformation mechanism maps for each mineral are required together with mixing relations for multiple deformation mechanisms. We construct reference deformation mechanism maps for calcite and alkali-feldspars that are based on theoretical expressions for constitutive relations, together with experimental or molecular dynamic estimates of constitutive parameters. A thermodynamically based mixing relation is employed that enables bulk constitutive relations to be established for mixtures of mineral phases and deformation mechanisms with a range of grain sizes. This provides a basis for comparison and understanding of experimental results. We map out fields on deformation mechanism maps where switches in the relative strengths of calcite and quartz and of feldspar and quartz occur. We introduce the concept of geometrically necessary deformation mechanisms that minimise the energy of the system.
PY - 2020
EP - 104056
T2 - Journal of Structural Geology
TI - The relative strengths of deforming mineral phase assemblages: Geometrically necessary deformation mechanisms
UR - http://www.sciencedirect.com/science/article/pii/S0191814119305036
VL - 137
SN - 0191-8141
ER -