Microscopy of Magmatic Rocks

Abstract

This course provides basic knowledge in microscopy of igneous rocks. Apart from the identification of common igneous minerals in thin sections, mineral assemblages, textures and structures will be investigated and the results of microscopy will be combined with igneous phase equilibria to understand generation, differentiation and emplacement of igneous rocks.

Objective

The principal goal of this course is to acquire expertise in : (1) optical determination of minerals in igneous rocks using the polarizing microscope (2) Identification of igneous rocks basing on modal mineralogy, structure and texture; (3) Interpretation of textures and structures and associated igneous processes; (4) Application of phase diagrams to natural rocks.

Content

This practical course bases on the course 'Microscopy of metamorphic rocks' (A. Galli), that is taught immediately before this course, where basic knowledge in optical mineralogy and the use of the polarizing microscope is acquired. In this course, the most important (common) igneous minerals and rocks are studied in thin sections under the polarizing microscope. Mineral assemblages, structures, textures and crystallization sequences are determined and utilized to understand the generation, differentiation and emplacement of igneous rocks. In addition, we will apply igneous phase equilibria that have been introduced in other lectures (such as magmatism and metamorphism I&II at ETH or an equivalent igneous petrology course) to natural rock samples in order to constrain qualitatively parental magma compositions and crystallization conditions. The range of investigated rocks encompasses mantle rocks, tholeiitic, calc-alkaline and alkaline plutonic and volcanic rocks that contain the most common igneous minerals.

Resources