Petrology Midterm II
Powerpoints 9-15
Quizzes 4-5
Homework 3
Winter Chapters 11-20
11) Diversification of Magmas
• Magmatic Differentiation driven by:
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Fractional Crystallization
Diffusion-controlled Crystallization
Volatile Transport
Liquid Immiscibility
• Crustal Melting (Anatexis)
• Magma Mixing
• Crustal Assimilation
12) Mafic Layered Intrusions
• Formation – crystal fractionation vs. liquid fractionation
• Evidence for magmatic sedimentation in the Skaergaard
• Cumulate Stratigraphy of the Skaergaard
• Cumulate Stratigraphy of the Bushveld Complex
• Cumulate Stratigraphy of Duluth Layered Series
• Origin of the DLS Cyclic Zone
13) MORB
• Attributes of fast and slow spreading ridges
• Upper mantle and ocean Ccrust stratigraphy
• Compositional attributes and origins of NMORB and EMORB
14) Ocean Island Basalts (OIB)
• Structures and source of Mantle Plumes
• Chemical characteristics and origin of alkaline vs. tholeiitic OIB
magmas
• REE characteristics of OIB compared to NMORB and EMORB –
indicative of deep (garnet-bearing) mantle source
15) Continental Flood Basalts
• Relationship of mantle plumes and large igneous provinces (LIPs)
• Tectonic setting of the Columbia River Basalts
• Evidence for a mantle plume influencing the Midcontinent Rift
• Evidence against a mantle plume for the MCR
• Evidence for mafic crustal underplating of the MCR
• Origin of anorthositic rocks of the MCR
• Magmatic stages of the MCR
• Evidence for correlation of the Beaver River diabase and the
Greenstone flow
16) Island Arcs
• Tectonic components of an Island Arc
• Distinguishing Tholeiitic, Calc-Alkaline and Alkaline magma series
• Major element evidence of differentiation within IA magma series
(Harker Diagrams)
• Use of K in further distinguishing magma series and spatial variations
within IA
• Trace element characteristics of IA basalts compared to OIB (REE, Nb-Ta)
• Thermal structure and main variables that can affect the isotherms in IA
subduction zones
• Source of magmas in subduction zones; the role of water-bearing
minerals
• Affect of age of ocean crust and arc in “magma fertility”
17) Continental Arcs
• Why Continental Arcs vs. Island Arcs around the Pacific?
• Rock types and compositions of Continental Arcs vs. Island Arcs
• Variations in magmatism in the Andean arc (NVZ, CVZ, SVZ)
• Evolution of the Cascade Arc
• Differences between Cascade and Andean Arcs
• The MASH model for arcs
18) Origin of Granites
• Fractional Crystallization vs. Partial Melting
• Composite emplacement of “granitoid” batholiths
• Classifications of granitoids
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Chemical (peraluminous, metaluminous, peralkaline)
Mineralogical (QAP)
Source (SIAM classification)
Tectonic setting (orogenic, anorogenic, transitional)
• Why is Granite so common?
19) Alkaline Magmatism / 20) Anorthosites