Igneous Rocks Magma GLGY 209-02 Fall 2024 PDF

# GLGY 209-02 EARTH Fall 2024 ## Igneous rocks - magma ## General information * Rock: any naturally formed solid material composed of one or more minerals and having some degree of chemical and mineralogical constancy. ### Igneous ### Sedimentary ### Metamorphic ## General information - IGNEO...

# GLGY 209-02 EARTH Fall 2024 ## Igneous rocks - magma ## General information * Rock: any naturally formed solid material composed of one or more minerals and having some degree of chemical and mineralogical constancy. ### Igneous ### Sedimentary ### Metamorphic ## General information - IGNEOUS ROCKS * Volcanoes and related lava flows; * Cross-cutting relations to surrounding rocks; * Thermal effects on the adjacent rocks; * Lack of fossils and stratification; * Generally structureless rocks composed of interlocking grains; * Mostly located in Precambrian or orogenic terranes; * Characteristic shapes and kinds of occurrence (e.g. sills, stocks, batholiths, lava flows, etc). ## IGNEOUS ROCKS - Generalities * Igneous rocks - form from crystallization of minerals from a magma as it cools. * Magmas originate deep within the Earth's crust and upper mantle. * ~700°C rocks will start to melt (melting temperature depends on chemical composition). ## IGNEOUS ROCKS - major groups * Two main groups of igneous rocks according to magma depth of cooling. * **Intrusive** (magma cools and crystallizes within the Earth's crust). * **Extrusive** (magma cools and crystallizes at the surface of the Earth). ## INTRUSIVE vs. EXTRUSIVE ROCKS * **Pink granite** * **Rounded spindle bomb**