Title

Integrated electron backscatter diffraction and energy-dispersive X-Ray spectroscopy analysis on polymorph phase transitions

Presentation Type

Presentation

Abstract

This research project has utilized the new scanning electron microscope (SEM) in the Dept. of Geosciences to conduct chemical and crystallography analysis of polymorphs- minerals that have the same chemical formula, but different crystal structure. Specifically, this study explores phase transitions in the Al2SiO5 minerals- kyanite, sillimanite, and andalusite. Aluminous schists in the Goat Mountain area of the Clearwater metamorphic core complex in northern Idaho contain all three of these minerals. Electron backscatter diffraction (EBSD) and energy-dispersive X-Ray spectroscopy (EDS) were the primary techniques that were applied. This report addresses the chemistry and microstructure of these rocks through an integrated mineral chemistry (EDS) and crystallographic (EBSD) study. The primary goal is to gain a better understanding of the tectonic history of the Clearwater area with respect to deformation of these rocks. In preparation for analysis, thin sections were polished using the Buehler VibroMet 2 Vibratory Polisher and carbon coated with the Denton Vacuum Desk V. Sample preparation is extremely critical to get clear results. EDS provides the chemical evaluation of the thin section and element maps were produced. EBSD generates crystal orientation maps and patterns needed to interpret the microstructure. The Clearwater metamorphic core complex consists of mid crust that is exhumed during crustal extension. Based on lithological differences, the complex is categorized into two distinct zones: the internal zone-basement amphibolite, anorthosite, and schist; and the external zone- metamorphosed Middle Proterozoic Belt Supergroup sediments and pre-Belt schist and gneiss. The area of focus was on the unique schists near Goat Mountain and the bounding Jug Rock shear zone to the east. The results will allow us to interpret the processes of the earth with a better understanding and will benefit future research.

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Apr 12th, 4:20 PM Apr 12th, 4:40 PM

Integrated electron backscatter diffraction and energy-dispersive X-Ray spectroscopy analysis on polymorph phase transitions

UC 331

This research project has utilized the new scanning electron microscope (SEM) in the Dept. of Geosciences to conduct chemical and crystallography analysis of polymorphs- minerals that have the same chemical formula, but different crystal structure. Specifically, this study explores phase transitions in the Al2SiO5 minerals- kyanite, sillimanite, and andalusite. Aluminous schists in the Goat Mountain area of the Clearwater metamorphic core complex in northern Idaho contain all three of these minerals. Electron backscatter diffraction (EBSD) and energy-dispersive X-Ray spectroscopy (EDS) were the primary techniques that were applied. This report addresses the chemistry and microstructure of these rocks through an integrated mineral chemistry (EDS) and crystallographic (EBSD) study. The primary goal is to gain a better understanding of the tectonic history of the Clearwater area with respect to deformation of these rocks. In preparation for analysis, thin sections were polished using the Buehler VibroMet 2 Vibratory Polisher and carbon coated with the Denton Vacuum Desk V. Sample preparation is extremely critical to get clear results. EDS provides the chemical evaluation of the thin section and element maps were produced. EBSD generates crystal orientation maps and patterns needed to interpret the microstructure. The Clearwater metamorphic core complex consists of mid crust that is exhumed during crustal extension. Based on lithological differences, the complex is categorized into two distinct zones: the internal zone-basement amphibolite, anorthosite, and schist; and the external zone- metamorphosed Middle Proterozoic Belt Supergroup sediments and pre-Belt schist and gneiss. The area of focus was on the unique schists near Goat Mountain and the bounding Jug Rock shear zone to the east. The results will allow us to interpret the processes of the earth with a better understanding and will benefit future research.