GEOL 3313 Petrology of Igneous and Metamorphic Rocks Study Guide for Final Examination Glen Mattioli

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1 GEOL 3313 Petrology of Igneous and Metamorphic Rocks Study Guide for Final Examination Glen Mattioli Chapter 5: Crystal-Melt phase diagrams Effect of water pressure on feldspar stability Hypersolvus vs. sub-solvus granites o Petrographic/Mineralogic characteristics o Binary phase relations Ternary Phase Diagrams o An-Ab-Kf o Intersection of liquidus surface o Thermal Valley o Solvus or miscibility gaps Ternary feldspar tie-lines Natural feldspar compositions o Rhyolite pumice o Trachybasalt Liquid line of descent: effect of late stage xtals Water saturated ternary equilibria o Effect of pressure o Comparison with natural modes Models for the origin of Granites o Fractional crystallization o Assimilation o Magma mixing o Sub-solidus recrystallization Pyroxene quadrilateral Mica and amphibole melt equilibria: effect of fo 2 Thermal stability of volatile minerals (see again for met-pet) Assessing disequilibrium o Grain shape o Reaction rims o Compositional zoning o Inappropriate phases Chapter 6: The Mantle (from Hess) Internal Earth structure pie diagram o Crust o Mantle Upper Transition Zone Lower o Core

2 Outer core Inner core Internal Earth divisions o Depths o Volumes o Mass Comparison of Earth with other terrestrial planets Seismic wave velocity and density with depth End-member mantle convection models o Whole mantle o 2 layer convection Trace element concentrations o Solar atmosphere concentrations o C1 carbonaceous chondrites vs. solar photosphere Bulk Earth chemical models o Pyrolite o Model mantle o Core Schematic rift structure o Relationship to mantle melting/upwelling o Lithosphere/Asthenosphere boundary o 800 C isotherm Peridotite textures Mantle xenoliths o Modes of mantle minerals o Major element compositions of sp vs. gt. Peridotites o Hydrous mineral compositions MgO vs. major element variation diagrams Depletion vs. Fertility Trace element characteristics o REE patterns Decoupled major and trace element concentrations Chapter 11: Generation of Magma Causes of mantle melting o Temperature o Pressure o Fluids Melting environments for Oceanic lithosphere Melting environments for Continental lithosphere Peridotite melting relations Volatile-free primordial mantle composition Mantle metasomatism o Affect on major elements o Trace elements o Isotopes

3 Melt interfacial angles Di-Fo-Qtz phase relations and MORB generation o Effect of CO 2 pressure Fractional vs. Batch (equilibrium) melting Alkali basalt generation o Effect of CO 2 and H 2 O pressure on melt composition o Effect of melt fraction Trace element fractionation systematics o Derived liquid o Residual solid REE patterns of low degree partial melts Melt generation in a metasomatized mantle Melt generation in the continental crust Melt segregation o Effect of volume o Melting process o Syndeformational melting -> migmatites (see met-pet) Chapter 7 and 8: Primary melts and MORB generation (from Hess) Mantle melts: definitions o Primary melts o Primative melts o Parental melts Low pressure vs. high pressure multiple saturation Trace and major element characteristics of primary mantle melts Tests for whether a melt is primary Spreading center profiles o Slow Atlantic o Fast Pacific Thickness and P-wave velocity of oceanic crust FAMOUS glass compositions AMAR valley MgO variation diagrams Characteristics (major element) of plag., cpx, olivine fractionation Compatible trace element behavior vs. Mg. Number REE variations o N-MORB (normal) o T-MORB (transitional) o E-MORB (enriched) Sm/Nd and Rb/Sr isotopic variations The mantle array HSFE/LILE patterns Consensus model for MORB generation Chapter 10 and 11 (Hess) and Chapter 12 and 13 (Best) Tectonic distribution of modern island arcs Schematic island arc cross-section

4 AFM plots o Calc-alkaline trend o Tholeiite trend K 2 O vs. SiO 2 trends for modern island arcs o Low-K series o Calc-alkaline series o High-K series o Shoshonite series Generalized phenocryst assemblages for island arc series Average compositions for island arc series o Major elements o Trace elements o SiO 2 variation diagrams o REE concentrations vs. Mg# e-nd vs. e-sr: comparison of island arcs with the Mantle Array Pb-Pb isotopes and the need for minor continental sediment input Trace element characteristics of altered MORB and sediments Andean volcanism Generalized composition of basaltic andesites Plutons of the Sierra Nevada, Peninsular Ranges and the Canadian Pacific Northwest Major and trace element zonation in the Sierra Nevada batholiths Sr-isotopic contours in the Sierra Nevada batholiths Chapter 14: Metamorphic Rocks and Metamorphism Metamorphic driving forces P-T conditions of metamorphism Relationship of metamorphism with plate tectonics Simple definitions: o Metamorphism o Diagenesis o Melting Equilibration in metamorphic rocks features o Preservation of relic textures o Recrytallization o Increase in grain size o Crystallization of new minerals and fabrics o Tectonites Before and after metamorphism: volcanic tuff example Hydrothermal breakdown of primary igneous minerals Relic phenocrysts Ostwald ripening: grain size growth with time Prograde thermal metamorphism, an example: o Diabase o Greenstone o Amphibolite

5 o Granofels Textural Definitions o Porphyroblastic o Poikiloblasts o Epitaxial growth o Cataclasis o Tectonites Foliations Lineations Fractal nature of deformation Tectonic fabric development in greywacke Cleavage formation o Slaty cleavage o Crenulation cleavage o Cleavage Transposition Examples of ductile metamorphism o Undeformed Archean pillow basalts o Highly deformed and sheared pillows Recognition of metamorphic protoliths o Relic fabrics o Field relations o Bulk chemistry Global average shale composition End-member protoliths o Ultramafic o Mafic o Quartzo-feldspathic o Calc-silicate and calcareous o Ferruginous Factors controlling metamorphism o Temperature o Pressure o Fluids o Deviatoric stress Schematic Continental convergent margin and its relationship to metamorphism Chapter 12 continued: Metamorphic Terranes, Facies, and Reactions Generalized metamorphic terranes o Ocean ridge o Regional o Burial o Contact o Dynamic shear o Impact Prograde vs, Retrograde metamorphic pathways o Decarbonation

6 o Dehydration Onawa Contact Metamorphic Aureole o Changes in composition o Changes in texture o Relationship with fluids and heat Examples of Retrograde metamorphism o Eclogite o Epidote veins in granodiorite Crestmore felsic metamorphic intrusion and skarn: changes in mineralogy o Low grade: Forsterite zone o High grade: Garnet zone Scottish Barrovian zones in pelites Index minerals and isograds Metamorphic facies and field gradients Facies reactions Pressure-Temperature-Time paths Progressive ductile deformation Polymetamorphism L-S tectonite fabrics Pressure solution and volume loss: formation of spaced cleavage Compatibility diagrams o No solid solution o With solid solution AFC composition diagrams AFM projection diagrams Overview of metamorphic mineral reactions o Solid-solid o Solid-Fluid o Discontinuous reactions o Continuous reactions Basalt -> Granulite -> Eclogite transition Compositional effects on mineral stability: ACF in granulites Devolatilization reactions