CEE 437 Lecture 2 Earth Materials I Earth Structure and Minerals Thomas Doe

Outline Global tectonic setting Global tectonic setting Rock cycle Rock cycle Rock forming minerals Rock forming minerals Paper 1 Paper 1

Global Structure Based mainly on seismic information and meteorite compositions Based mainly on seismic information and meteorite compositions Crust ~25-75 km depending varying under continents and oceans Crust ~25-75 km depending varying under continents and oceans

Velocity Variation with Depth

Global Structure

Development of Plate Tectonics Evidence from ocean floor magnetism and ages Evidence from ocean floor magnetism and ages Evidence from seismicity Evidence from seismicity Evidence from cross-continent correlations of rocks Evidence from cross-continent correlations of rocks

Global Seismicity

Benioff Zone

Seafloor Spreading — Sediment Ages

Sea-floor Spreading Mantle convection driven Mantle convection driven

Evolution of Spreading Sea Floor — Atlantic Analog

Convergent Margins Ocean to Continent Ocean to Continent Continent to Continent Continent to Continent

Convergent Margin - Continental

Subduction Zone – Island Arc Subduction Zone – Island Arc

Evolution of Continents — North American Craton

North American Accretion

Rock Cycle Metamorphic Rocks Sedimentary Rocks Igneous Rocks Sediments Lithification Magma Weathering, Erosion Burial, metamorphism, recrystallization Melting Crystallization at depth or extrusion at surface Burial, metamorphism, recrystallization

Mineral Differentiation Plate tectonics and Igneous Processes Plate tectonics and Igneous Processes selective melting, selective recrystallization selective melting, selective recrystallization differentiation by density differentiation by density Weathering and Erosion Weathering and Erosion Selective weathering Selective weathering Concentration of quartz (pure Si0 2 ) Concentration of quartz (pure Si0 2 ) Conversion of alumino-silicates to clays Conversion of alumino-silicates to clays Concentration of soluble residues in seawater Concentration of soluble residues in seawater Deposition Deposition Courser materials near sediment source Courser materials near sediment source Finer materials far from sediment source Finer materials far from sediment source Redeposition of salts and solutes by evaporative (Na,KCl; CaSO 4 ) or biological processes (CaCO 3,; ) Redeposition of salts and solutes by evaporative (Na,KCl; CaSO 4 ) or biological processes (CaCO 3,; )

Differentiation of Crustal Composition Weathering differentiating towards higher Silica Preferential melting of high-silica materials Concentration of C, Ca, Na, K in sea and air Original basaltic composition of crust Carbonate concentrated by organic processes

Bowen Reaction Series How to get many different rocks from one melt composition? How to get many different rocks from one melt composition? Differentiation by selective crystallization and removal from system Differentiation by selective crystallization and removal from system

Bowen’s Reaction Series

Crustal Composition Main Elemental Groups Main Elemental Groups Silica Silica Aluminum Aluminum Ferro-Magnesian Ferro-Magnesian Ca, Na, K Ca, Na, K

Elemental Fates Silicon tends to concentrate in crust — quartz is very long lived Silicon tends to concentrate in crust — quartz is very long lived Aluminum — transforms from feldspars to clays Aluminum — transforms from feldspars to clays Mica — transform to clays Mica — transform to clays Fe-Mg-Ca-Na-K concentrate in some clays and micas, concentrate in oceans in biosphere Fe-Mg-Ca-Na-K concentrate in some clays and micas, concentrate in oceans in biosphere

Differentiation in Crystallization Versus Differentiation in Weathering Olivine Pyroxene Amphibole Biotite Muscovite Quartz Ca,Mg Feldspars K- Feldspars High Temperature, Low Silica, Hi Fe Mg Low Temperature, High Silica, Low Fe Mg Fast Weathering Slow Weathering

Sedimentary Differentiation Sorting by Deposition Medium Sorting by Deposition Medium Sorting by Energy Sorting by Energy

Mineral Definition Naturally occurring material with unique combination of chemical composition and crystalline structure Naturally occurring material with unique combination of chemical composition and crystalline structure Natural non-minerals — glasses, coal, amorphous silica Natural non-minerals — glasses, coal, amorphous silica Pseudomorphs: diamond:graphite Pseudomorphs: diamond:graphite

Galena, PbS Graphite, C

Crystalline Structure of Calcite

Crystalline Symmetry Groups

Isomorphic Crystal Forms, Cubic System

Physical Properties Density (Gravity) Density (Gravity) Electrical Conductivity (Resisitivity) Electrical Conductivity (Resisitivity) Thermal Expansion Thermal Expansion Strength Strength Elasticity (Mechanical properties, Elasticity (Mechanical properties, Seismic/Acoustic Velocity Seismic/Acoustic Velocity Rheology (Plasticity,Viscosity) Rheology (Plasticity,Viscosity)

Properties and Mineral Symmetry

Tensor Properties of Crystals Cubic Group Lower Symmetry Groups General Form for Heat Flow (for example)

Discussion: How to Rock Properties Relate to Mineral Structure How will anisotropy vary with crystal symmetry class? How will anisotropy vary with crystal symmetry class? Rock Salt versus Quartz? Rock Salt versus Quartz? How will aggregates of minerals (with same mineral behave? How will aggregates of minerals (with same mineral behave? Cubic versus non cubic Cubic versus non cubic Rock fabric Rock fabric Material property contrasts Material property contrasts

Rock Forming Minerals Composition of Crust Composition of Crust Dominantly O, Si, Fe, Mg, Ca, Na, K Dominantly O, Si, Fe, Mg, Ca, Na, K Near surface importance of bio-processes Near surface importance of bio-processes Silicates from inorganic processes Silicates from inorganic processes Carbonates mainly from shell-forming organisms Carbonates mainly from shell-forming organisms

Crustal Composition Main Elemental Groups Main Elemental Groups Silica Silica Aluminum Aluminum Ferro-Magnesian Ferro-Magnesian Ca, Na, K Ca, Na, K

Major Silicate Groups Silicon Tetrahedron Silicon Tetrahedron separate tetrahedra — olivine separate tetrahedra — olivine single chains — pyroxene single chains — pyroxene double chains — amphibole double chains — amphibole sheet silicates — micas and clays sheet silicates — micas and clays framework silicates — feldspars (with Al substitution), quartz as pure silica framework silicates — feldspars (with Al substitution), quartz as pure silica

Silica Tetrahedron

Forms of Silicates

Deformation Mechanisms

Effects on Physical Properties Anisotropy Anisotropy Properties differ by direction Properties differ by direction Heterogeneity Heterogeneity Properties vary by location Properties vary by location Mineral properties may have strong anisotropy when crystals are aligned Mineral properties may have strong anisotropy when crystals are aligned Heterogeneity may have strong mechanical effects when different minerals have different deformation properties Heterogeneity may have strong mechanical effects when different minerals have different deformation properties

Minerals versus Rocks Minerals Elements Minerals Elements Anisotropy from crystal structure Anisotropy from crystal structure Elastic Properties Elastic Properties Thermal Properties Thermal Properties Optical Properties Optical Properties Deformation Deformation Shear transformations Shear transformations Dislocations Dislocations Rock Elements Intragranular Anisotropy from fabric Crystal anisotropy if preferred orientation Anisotropy from bedding, foliation, flow structures Intergranular Cements Microcracks Heterogeneity Mineral composition Other segregration processes

Clay Minerals Extremely Important Mineral Group Extremely Important Mineral Group Seals Seals Stability Stability Pore pressure Pore pressure Chemical interaction Chemical interaction Swelling Swelling Slaking Slaking Confusion as both “Size” and “Mineral” Classification Confusion as both “Size” and “Mineral” Classification

Clay Sources Weathering Weathering Hydrothermal Alteration Hydrothermal Alteration Deposition Deposition Clay Transformations Clay Transformations Feldspar  Illite Feldspar  Illite Ferro-Magnesian  Chlorite Ferro-Magnesian  Chlorite Volcanics (alkaline conditions)  Smectite Volcanics (alkaline conditions)  Smectite Volcanics (acidic conditions)  Kaolinite Volcanics (acidic conditions)  Kaolinite Bentonite: plastic, highly swelling Bentonite: plastic, highly swelling

Clay Units From West, Geology Applied to Engineering, Prentice Hall, 1995)

Two and Three-Layer Clay Structure From West, Geology Applied to Engineering, Prentice Hall, 1995)

Mixed Layer Clays From West, Geology Applied to Engineering, Prentice Hall, 1995)

Topics Mineral Definition Mineral Definition Rock Forming Minerals Rock Forming Minerals Physical Proprieties of Minerals Physical Proprieties of Minerals Mineral Identification Mineral Identification Mineral Lab Mineral Lab

Clay Viewed from Electron Microscope

Mineral Identification Density Density Hardness Hardness Color, luster (metallic, non-metalic, semi- metallic) Color, luster (metallic, non-metalic, semi- metallic) Crystalline habit Crystalline habit Cleavage Cleavage Optical microscopy Optical microscopy Mineral chemistry, x-ray diffraction Mineral chemistry, x-ray diffraction

Hardness Scale

X-Ray Diffraction Bragg’s Law

Weathering Fates Feldspars to clays (clays, shales) Feldspars to clays (clays, shales) Quartz endures (siltstones, sandstones) Quartz endures (siltstones, sandstones) Calcium recirculated into carbonate minerals by organic processes (limestones) Calcium recirculated into carbonate minerals by organic processes (limestones) Consequence: Consequence: Over time, evolution of less dense more silicic continental crust Over time, evolution of less dense more silicic continental crust

Engineering Implications “Style” of geology and geo-engineering problems varies with plate tectonic setting “Style” of geology and geo-engineering problems varies with plate tectonic setting Faulting, and structural complexity Faulting, and structural complexity Maturity of materials varies with plate tectonics setting Maturity of materials varies with plate tectonics setting Higher degree of more stable materials from sorting by weathering Higher degree of more stable materials from sorting by weathering Geohazards vary with plate tectonic setting Geohazards vary with plate tectonic setting

Paper and Paper Topics Paper I Topics Paper I Topics Columbia River Basalts – Origin, Structure, Hydrologic and Engineering Properties Columbia River Basalts – Origin, Structure, Hydrologic and Engineering Properties Geology and Engineering Geology of the Snoqualmie Pass Quadrangle Geology and Engineering Geology of the Snoqualmie Pass Quadrangle Clay Minerals – Origin, Crystal Structure, Engineering Properties Clay Minerals – Origin, Crystal Structure, Engineering Properties 6 Pages, 1.5 space, plus figures, include references. 6 Pages, 1.5 space, plus figures, include references.

Undergrad Presentations 1. Geologic History of Columbia Plateau 1. Geologic History of Columbia Plateau 2. Geologic History of Olympic Peninsula 2. Geologic History of Olympic Peninsula 3. Coal Mines of Newcastle, Washington 3. Coal Mines of Newcastle, Washington 4. Geological Issue Effecting Construction I-5 through Seattle 4. Geological Issue Effecting Construction I-5 through Seattle 5. The Seattle Fault 5. The Seattle Fault 6. Foundations on Peat 6. Foundations on Peat 7. Rock Slope Stability Problems in I Rock Slope Stability Problems in I Fracture Image Logging Technologies 8. Fracture Image Logging Technologies 9. Tunneling for Sound Transit 9. Tunneling for Sound Transit 10. Engineering Properties of Organic Soils in the Puget Sound Area 10. Engineering Properties of Organic Soils in the Puget Sound Area 11. Engineering Properties of Glacial Soils in the Puget Sound Area 12. Solute Transport in Fractured Rock 13. Economic Minerals of Washington State 14. Quarry Mines of Puget Sound 11. Engineering Properties of Glacial Soils in the Puget Sound Area 12. Solute Transport in Fractured Rock 13. Economic Minerals of Washington State 14. Quarry Mines of Puget Sound 15. Failure of Malpassat Dam 15. Failure of Malpassat Dam 16. Rock Tunnel Failures in the Alps 16. Rock Tunnel Failures in the Alps 17. Seattle Watershed Geology 17. Seattle Watershed Geology

Grad Requirements Add Goodman – Engineer as Artist (unless discuss with us otherwise) Add Goodman – Engineer as Artist (unless discuss with us otherwise)

Paper and Paper Topics Paper I Topics Paper I Topics Columbia River Basalts – Origin, Structure, Hydrologic and Engineering Properties Columbia River Basalts – Origin, Structure, Hydrologic and Engineering Properties Geology and Engineering Geology of the Snoqualmie Pass Quadrangle Geology and Engineering Geology of the Snoqualmie Pass Quadrangle Clay Minerals – Origin, Crystal Structure, Engineering Properties Clay Minerals – Origin, Crystal Structure, Engineering Properties 6 Pages, 1.5 space, plus figures, include references. 6 Pages, 1.5 space, plus figures, include references.