Over the past several decades, SEM based EBSD analysis has been extensively applied to the study of deformed rocks in geosciences. In this write-up the author reviews the present state-of-art in the application of EBSD to evaluating kinematics in tectonically deformed rocks. Unlike other branches of engineering and science, in structural geology, the geographic reference frame, its relation with the strain ellipsoid and collection of oriented field samples are critical in making scientifically sound interpretation of sense of shear. This requires the investigation of structures in the field as well as under the microscope (including SEM-EBSD) in the kinematic reference frame. In the present review, the author provides a detailed description of identification of this kinematic reference frame using field structures, when they are visible, or with the help of anisotropy of magnetic susceptibility (AMS) in the laboratory, when visible structures are not developed. A description of the recent advancements in sample preparation of geological samples for EBSD studies using broad ion beam polishing is also provided. Since quartz is the most commonly investigated mineral, whose crystallography is very well-established and exploited for kinematic studies, the author discusses several examples from his own research work in which kinematic analysis has been successfully carried out using quartz EBSD data. Examples are also discussed where kinematics deciphered at the microscopic scale can provide useful data to interpret and/or support larger scale deformation/tectonics.

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SEM-EBSD Studies of Tectonically Deformed Rocks and Kinematic Analysis

  • Manish A. Mamtani

摘要

Over the past several decades, SEM based EBSD analysis has been extensively applied to the study of deformed rocks in geosciences. In this write-up the author reviews the present state-of-art in the application of EBSD to evaluating kinematics in tectonically deformed rocks. Unlike other branches of engineering and science, in structural geology, the geographic reference frame, its relation with the strain ellipsoid and collection of oriented field samples are critical in making scientifically sound interpretation of sense of shear. This requires the investigation of structures in the field as well as under the microscope (including SEM-EBSD) in the kinematic reference frame. In the present review, the author provides a detailed description of identification of this kinematic reference frame using field structures, when they are visible, or with the help of anisotropy of magnetic susceptibility (AMS) in the laboratory, when visible structures are not developed. A description of the recent advancements in sample preparation of geological samples for EBSD studies using broad ion beam polishing is also provided. Since quartz is the most commonly investigated mineral, whose crystallography is very well-established and exploited for kinematic studies, the author discusses several examples from his own research work in which kinematic analysis has been successfully carried out using quartz EBSD data. Examples are also discussed where kinematics deciphered at the microscopic scale can provide useful data to interpret and/or support larger scale deformation/tectonics.