GEOL107 Lecture Notes - Lecture 3: Peridotite, Diorite, Mafic
27 Jul 2018
School
Department
Course
Professor
09.05.2017
Lecture Outline
1. Igneous Rocks
a. Origin and magmas
b. Textures and compositions
c. Names of igneous rocks
2. Volcanoes and Plutons
a. Magmas effects on eruptions
b. Types of volcanoes
c. Types of plutons
Quote of the day: “Fire……. Fire on the mountain……” – The Grateful Dead
Igneous Rocks
Origins and Magmas
• Definition of igneous rock – origin from cooling and subsequent crystallization
(solidification) of magma
• Magma – hot (1100C), liquid, melt elements
• Major elements present are
o Oxygen (O)
o Silicon (Si)
o Aluminum (Al)
o Iron (Fe)
o Calcium (Ca)
o Sodium (Na)
o Potassium (K)
o Magnesium (Mg)
• It also has dissolved gases like water (H2O), carbon dioxide (CO2)
• Magmas have a range of varying compositions, with two general “end-members”
• These are basaltic (mafic) or silicic (felsic)
Basaltic
• Magma composed of approx. 50% silica
• Have higher amounts of iron, magnesium, and calcium
• Lower amounts of potassium, sodium, dissolved gases
Silicic
• Composed of 65-77% SiO2
• Lower amounts of iron, magnesium, and calcium
• Higher amounts of potassium, sodium, and dissolved gases
Textures and Compositions
• Igneous rocks are subdivided based on their texture (big vs. small crystals, glass, holes in
rock) and composition (what minerals are found in rock)
• Texture tells story of formation
Textures of Igneous Rocks
Document Summary
Lecture outline: igneous rocks, origin and magmas, textures and compositions, names of igneous rocks, volcanoes and plutons, magmas effects on eruptions, types of volcanoes, types of plutons. Fire on the mountain the grateful dead. It also has dissolved gases like water (h2o), carbon dioxide (co2: magmas have a range of varying compositions, with two general end-members , these are basaltic (mafic) or silicic (felsic) 50% silica: have higher amounts of iron, magnesium, and calcium, lower amounts of potassium, sodium, dissolved gases. Silicic: composed of 65-77% sio2, lower amounts of iron, magnesium, and calcium, higher amounts of potassium, sodium, and dissolved gases. Igneous rocks are subdivided based on their texture (big vs. small crystals, glass, holes in rock) and composition (what minerals are found in rock: texture tells story of formation. Igneous rocks that contain lots of magnesium and iron rich minerals. Igneous rocks with minerals that have more silica potassium, and sodium.
