The viability of CL subgrain imaging for determining paleostresses in quartz

Abstract

The field of paleopiezometry has long been an important tool in the determination of paleo stresses. In order to make an as accurately as possible stress estimate, it is necessary that the microstructures used for paleopiezometry are measured as accurately as possible. This thesis aims to determine if cathodoluminescence (CL) imaging is a viable alternative or addition to light microscopy and/or electron backscatter diffraction (EBSD), with regards to subgrain detection and measurement. To achieve this aim, four different detection methods are each applied to four samples. These four methods are light microscopy, scanning electron microscopy with CL detector (SEM-CL), electron microprobe mapping and EBSD mapping. Three of the studied samples are naturally deformed and one experimentally. To determine the accuracy of the subgrain detection methods, stress estimates are made using paleopiezometry. These stress estimates are then compared to stress estimates made from recrystallized grain paleopiezometry of the same samples. The observations and data that results from this thesis indicates that while CL is a useful and fast method for detecting subgrains, it cannot be used without a second method to distinguish between subgrain boundaries and other microstructures i.e. Dauphiné twins.