Petrology Midterm I
Powerpoints 1-8
Quizzes 1-3
Homework 1-2
Winter Chapters 1-10
1) Introduction to Igneous Petrology and Earth’s
Physical and Chemical Structure
• Milestones to an understanding of igneous processes
• Chemical and Physical Structure of the Earth
• Heat Sources, heat transfer mechanisms and
geothermal gradients
• Relationships of mantle dynamics and plate tectonics
2) Classification of Igneous Rocks
• Goals of a classification scheme
• Essential minerals to ultramafic, mafic and felsic modal classification
schemes
• Normalization of modes for a ternary diagram
• Other modifiers for a complete description of an igneous rock
• Significance of bulk rock textures in gabbros – ophitic vs. intergranular
• The good and the bad of modal classification schemes
• Utility of cumulate classification schemes
• Chemical classification of volcanic
• Classifications of volcaniclastic rocks
3) Physical Igneous Petrology
• Physical and chemical properties of 4 main classes of lavas
• Contrast in eruptive character of basalts vs. intermed/felsic lavas
• Distinguishing subaerial from submarine basalt eruptions
• 3 types of pyroclastic deposits
• Intrusion shape types
• Styles and mechanisms of magma emplacement at different crustal
depths
4) Introduction to Thermodynamics
• What is Thermodynamics?
• 3 states of energy – unstable, metastable, stable
• What is Gibbs Free Energy and why is pertinent to igneous systems?
• What are the main variables controlling G?
• What are intrinsic vs. extrinsic variables
• Reference state conditions for measuring G
• Understand why melting curves in P-T space have a positive slope
(related to P-V and T-S relationships)
5) One- and Two-Component Phase Diagrams
• Empirical and experimental evidence on how magmas crystallize
• Basic parameters of Phase Diagrams (P, T, X)
• Gibbs Phase Rule and determining the degrees of freedom on phase
diagrams
• One-component systems – Qtz, H2O
• Two-component systems with Solid Solution – An-Ab, Fo-Fa
• Two-component systems with a Eutectic – Di-An
• Two-component systems with a Peritectic – Fo(-En)-Qtz (extra credit)
• The lever rule in determining the % of liquid and solid during
equilibrium crystallization
• Understand how processes of melting and crystallization can be
portrayed on binary phase diagrams.
6) Multi-component Phase Diagrams
An-Fo-Di ternary system
• Understand how equilibrium melting and crystallization are portrayed
• Understand how the lever rule is used to determine the proportion
and compositions of solid phases and the liquid
• Understand the rocks formed due to equilibrium crystallization vs.
fractional crystallization
7) Major, Minor and Trace Element Chemistry
• General major, minor, and trace element constituents of a basalt
• General compositional differences between mafic and felsic magmas
• What CIPW norms are used for
• X-Y Harker diagrams – indicators of magmatic differentiation in
magmatic series
• AFM diagrams – discriminate what?
• Difference between HFSE and LIL trace elements
• Concept of trace element compatibility and definition of mineralliquid partition coefficients
• Behavior of REE during partial melting and fractional crystallization
8) Mantle Melting and the Generation of Basaltic Magma
• Lherzolitic composition of the mantle
• Variation in the aluminous phase with depth – Pl – Sp – Gt
• Geothermal gradients compared to mantle melting curves
• 3 ways to get the mantle to melt – increase T, adiabatic
decompression, increased volatiles.
• 5 ways to create compositional diversity among mafic magmas