0000000000203727
AUTHOR
António Moura
Microstructural analysis of shearband boudin - preliminary results
The internal structure of a shearband boudin resulting from an original igneous, hydrothermal or metamorphic segregation tabular rigid body is a subject of scientific interest. It allows understanding the deformation mechanisms acting on homogeneous quartz aggregate activated during simple shear progressive deformation. This communication is focused on the characterization of two main structural aspects: (i) the existence of different internal domains in shearband boudins; (ii) the development of internal structures related with its genesis and evolution, namely, secondary shear planes c’ type-I and c’ type-II, parameter B-t (mass accumulation sector on blunt tip of shearband boudin) and S-…
P-T path development derived from shearband boudin microstructure
This work focuses on the development of a regional P-T-path from the Malpica-Lamego Ductile Shear Zone, NW Portugal, based on the microstructures of shearband boudins evolved during progressive simple shear. The combination of microstructural analysis, fluid inclusion studies, crystallographic pre- ffered orientation and fractal geometry analyses, allows to link several stages in the internal evolution of the boudin to regional P-T conditions. The boudinage process is initiated under differential stress after the original layer achieved sufficient viscosity contrast relative to the surrounding matrix. Two main transformations occur simultaneously: i) change in the external shape with contin…
Interpretative model of shearband boudins internal evolution in HT ductile shear zones
The internal structure of a shearband boudin resulting from an original igneous, hydrothermal or metamorphic segregation tabular rigid body is a subject of scientific interest. It allows understanding the deformation mechanisms acting on homogeneous quartz aggregate activated during simple shear progressive deformation. This work is focused on the characterization of the internal evolution of shearband boudins, using microtextural analysis, fluid inclusions studies, fractal and OCP analysis. The proposed interpretative model shows the several structural stages that can be well established during the process of the internal evolution of shearband boudin.