CEE 437 Lecture CEE 437 Lecture 22

Earth Materials IEarth Materials IEarth Structure Earth Structure

and Mineralsand MineralsThomas DoeThomas Doe

OutlineOutline Global tectonic settingGlobal tectonic setting Rock cycleRock cycle Rock forming mineralsRock forming minerals Paper 1Paper 1

Global StructureGlobal Structure Based mainly on seismic information Based mainly on seismic information

and meteorite compositionsand meteorite compositions Crust ~25-75 km depending varying Crust ~25-75 km depending varying

under continents and oceansunder continents and oceans

Velocity Variation with Velocity Variation with DepthDepth

Global StructureGlobal Structure

Development of Plate Development of Plate TectonicsTectonics

Evidence from ocean floor Evidence from ocean floor magnetism and agesmagnetism and ages

Evidence from seismicityEvidence from seismicity Evidence from cross-continent Evidence from cross-continent

correlations of rockscorrelations of rocks

Global SeismicityGlobal Seismicity

Benioff ZoneBenioff Zone

Seafloor Spreading — Seafloor Spreading — Sediment AgesSediment Ages

Sea-floor SpreadingSea-floor Spreading Mantle convection drivenMantle convection driven

Evolution of Spreading Evolution of Spreading Sea Floor — Atlantic Sea Floor — Atlantic

AnalogAnalog

Convergent MarginsConvergent Margins Ocean to ContinentOcean to Continent Continent to ContinentContinent to Continent

Convergent Margin - Convergent Margin - Continental Continental

Subduction Zone – Subduction Zone – Island ArcIsland Arc

Evolution of Continents Evolution of Continents — North American — North American

CratonCraton

North American North American AccretionAccretion

Rock CycleRock 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 DifferentiationMineral Differentiation Plate tectonics and Igneous ProcessesPlate tectonics and Igneous Processes

selective melting, selective recrystallizationselective melting, selective recrystallization differentiation by densitydifferentiation by density

Weathering and ErosionWeathering and Erosion Selective weatheringSelective weathering Concentration of quartz (pure Si0Concentration of quartz (pure Si022)) Conversion of alumino-silicates to claysConversion of alumino-silicates to clays Concentration of soluble residues in seawaterConcentration of soluble residues in seawater

DepositionDeposition Courser materials near sediment sourceCourser materials near sediment source Finer materials far from sediment sourceFiner materials far from sediment source Redeposition of salts and solutes by evaporative Redeposition of salts and solutes by evaporative

(Na,KCl; CaSO(Na,KCl; CaSO44) or biological processes (CaCO) or biological processes (CaCO3,; 3,; ) )

Differentiation of Crustal Differentiation of Crustal CompositionComposition

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 SeriesBowen Reaction Series

How to get many different rocks How to get many different rocks from one melt composition?from one melt composition?

Differentiation by selective Differentiation by selective crystallization and removal from crystallization and removal from systemsystem

Bowen’s Reaction SeriesBowen’s Reaction Series

Crustal CompositionCrustal Composition Main Elemental GroupsMain Elemental Groups

SilicaSilica AluminumAluminum Ferro-MagnesianFerro-Magnesian Ca, Na, KCa, Na, K

Elemental FatesElemental Fates Silicon tends to concentrate in crust Silicon tends to concentrate in crust

— quartz is very long lived— quartz is very long lived Aluminum — transforms from Aluminum — transforms from

feldspars to claysfeldspars to clays Mica — transform to clays Mica — transform to clays Fe-Mg-Ca-Na-K concentrate in some Fe-Mg-Ca-Na-K concentrate in some

clays and micas, concentrate in clays and micas, concentrate in oceans in biosphereoceans in biosphere

Differentiation in Differentiation in Crystallization Versus Crystallization Versus

Differentiation in Differentiation in WeatheringWeathering

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 Sedimentary DifferentiationDifferentiation

Sorting by Deposition MediumSorting by Deposition Medium Sorting by EnergySorting by Energy

Mineral DefinitionMineral Definition Naturally occurring material with Naturally occurring material with

unique combination of chemical unique combination of chemical composition and crystalline composition and crystalline structurestructure

Natural non-minerals — glasses, Natural non-minerals — glasses, coal, amorphous silicacoal, amorphous silica

Pseudomorphs: diamond:graphitePseudomorphs: diamond:graphite

Galena, PbS Graphite, C

Crystalline Structure of Crystalline Structure of CalciteCalcite

Crystalline Symmetry Crystalline Symmetry GroupsGroups

Isomorphic Crystal Forms, Isomorphic Crystal Forms, Cubic SystemCubic System

Physical PropertiesPhysical Properties Density (Gravity)Density (Gravity) Electrical Conductivity (Resisitivity)Electrical Conductivity (Resisitivity) Thermal ExpansionThermal Expansion StrengthStrength Elasticity (Mechanical properties, Elasticity (Mechanical properties,

Seismic/Acoustic VelocitySeismic/Acoustic Velocity Rheology (Plasticity,Viscosity)Rheology (Plasticity,Viscosity)

Properties and Mineral Properties and Mineral SymmetrySymmetry

Tensor Properties of Tensor Properties of CrystalsCrystals

Cubic Group

Lower Symmetry Groups

General Form for Heat Flow (for example)

Discussion: How to Rock Discussion: How to Rock Properties Relate to Properties Relate to Mineral StructureMineral Structure

How will anisotropy vary with How will anisotropy vary with crystal symmetry class?crystal symmetry class? Rock Salt versus Quartz?Rock Salt versus Quartz?

How will aggregates of minerals How will aggregates of minerals (with same mineral behave?(with same mineral behave? Cubic versus non cubicCubic versus non cubic Rock fabricRock fabric Material property contrastsMaterial property contrasts

Rock Forming MineralsRock Forming Minerals Composition of CrustComposition of Crust

Dominantly O, Si, Fe, Mg, Ca, Na, KDominantly O, Si, Fe, Mg, Ca, Na, K Near surface importance of bio-Near surface importance of bio-

processesprocesses Silicates from inorganic processesSilicates from inorganic processes Carbonates mainly from shell-forming Carbonates mainly from shell-forming

organismsorganisms

Crustal CompositionCrustal Composition Main Elemental GroupsMain Elemental Groups

SilicaSilica AluminumAluminum Ferro-MagnesianFerro-Magnesian Ca, Na, KCa, Na, K

Major Silicate GroupsMajor Silicate Groups Silicon TetrahedronSilicon Tetrahedron

separate tetrahedra — olivineseparate tetrahedra — olivine single chains — pyroxenesingle chains — pyroxene double chains — amphiboledouble chains — amphibole sheet silicates — micas and clayssheet silicates — micas and clays framework silicates — feldspars (with Al framework silicates — feldspars (with Al

substitution), quartz as pure silicasubstitution), quartz as pure silica

Silica TetrahedronSilica Tetrahedron

Forms of SilicatesForms of Silicates

Deformation Deformation MechanismsMechanisms

Effects on Physical Effects on Physical PropertiesProperties

AnisotropyAnisotropy Properties differ by directionProperties differ by direction

HeterogeneityHeterogeneity Properties vary by locationProperties vary by location

Mineral properties may have strong Mineral properties may have strong anisotropy when crystals are alignedanisotropy when crystals are aligned

Heterogeneity may have strong mechanical Heterogeneity may have strong mechanical effects when different minerals have effects when different minerals have different deformation propertiesdifferent deformation properties

Minerals versus RocksMinerals versus Rocks Minerals ElementsMinerals Elements

Anisotropy from crystal Anisotropy from crystal structurestructure

Elastic PropertiesElastic Properties Thermal PropertiesThermal Properties Optical PropertiesOptical Properties

DeformationDeformation Shear transformationsShear transformations DislocationsDislocations

Rock ElementsRock Elements IntragranularIntragranular

Anisotropy from fabricAnisotropy from fabric Crystal anisotropy if Crystal anisotropy if

preferred orientationpreferred orientation Anisotropy from bedding, Anisotropy from bedding,

foliation, flow structuresfoliation, flow structures IntergranularIntergranular

CementsCements MicrocracksMicrocracks

HeterogeneityHeterogeneity Mineral compositionMineral composition Other segregration Other segregration

processesprocesses

Clay MineralsClay Minerals Extremely Important Mineral GroupExtremely Important Mineral Group

SealsSeals StabilityStability Pore pressurePore pressure Chemical interactionChemical interaction SwellingSwelling SlakingSlaking

Confusion as both “Size” and Confusion as both “Size” and “Mineral” Classification“Mineral” Classification

Clay SourcesClay Sources WeatheringWeathering Hydrothermal AlterationHydrothermal Alteration DepositionDeposition Clay TransformationsClay Transformations

Feldspar Feldspar Illite Illite Ferro-Magnesian Ferro-Magnesian Chlorite Chlorite Volcanics (alkaline conditions) Volcanics (alkaline conditions) Smectite Smectite Volcanics (acidic conditions) Volcanics (acidic conditions) Kaolinite Kaolinite

Bentonite: plastic, highly swellingBentonite: plastic, highly swelling

Clay UnitsClay Units

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

Two and Three-Layer Clay Two and Three-Layer Clay StructureStructure

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

Mixed Layer ClaysMixed Layer Clays

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

TopicsTopics Mineral DefinitionMineral Definition Rock Forming MineralsRock Forming Minerals Physical Proprieties of MineralsPhysical Proprieties of Minerals Mineral IdentificationMineral Identification Mineral LabMineral Lab

Clay Viewed from Clay Viewed from Electron MicroscopeElectron Microscope

Mineral IdentificationMineral Identification DensityDensity HardnessHardness Color, luster (metallic, non-metalic, Color, luster (metallic, non-metalic,

semi-metallic)semi-metallic) Crystalline habitCrystalline habit CleavageCleavage Optical microscopyOptical microscopy Mineral chemistry, x-ray diffractionMineral chemistry, x-ray diffraction

Hardness ScaleHardness Scale

X-Ray DiffractionX-Ray Diffraction

spacing lattice,angle incidence,wavelength,sin2

dd

Bragg’s Law

Weathering FatesWeathering Fates Feldspars to clays (clays, shales)Feldspars to clays (clays, shales) Quartz endures (siltstones, sandstones)Quartz endures (siltstones, sandstones) Calcium recirculated into carbonate Calcium recirculated into carbonate

minerals by organic processes minerals by organic processes (limestones)(limestones)

Consequence:Consequence: Over time, evolution of less dense more Over time, evolution of less dense more

silicic continental crustsilicic continental crust

Engineering ImplicationsEngineering Implications ““Style” of geology and geo-engineering Style” of geology and geo-engineering

problems varies with plate tectonic settingproblems varies with plate tectonic setting Faulting, and structural complexityFaulting, and structural complexity

Maturity of materials varies with plate Maturity of materials varies with plate tectonics settingtectonics setting Higher degree of more stable materials from Higher degree of more stable materials from

sorting by weatheringsorting by weathering Geohazards vary with plate tectonic Geohazards vary with plate tectonic

settingsetting

Paper and Paper TopicsPaper and Paper Topics Paper I TopicsPaper I Topics Columbia River Basalts – Origin, Columbia River Basalts – Origin,

Structure, Hydrologic and Structure, Hydrologic and Engineering PropertiesEngineering Properties

Geology and Engineering Geology of Geology and Engineering Geology of the Snoqualmie Pass Quadranglethe Snoqualmie Pass Quadrangle

Clay Minerals – Origin, Crystal Clay Minerals – Origin, Crystal Structure, Engineering PropertiesStructure, Engineering Properties

6 Pages, 1.5 space, plus figures, 6 Pages, 1.5 space, plus figures, include references.include references.

Undergrad PresentationsUndergrad Presentations 1. Geologic History of Columbia Plateau1. Geologic History of Columbia Plateau 2. Geologic History of Olympic Peninsula2. Geologic History of Olympic Peninsula 3. Coal Mines of Newcastle, Washington3. Coal Mines of Newcastle, Washington 4. Geological Issue Effecting Construction I-5 through Seattle4. Geological Issue Effecting Construction I-5 through Seattle 5. The Seattle Fault5. The Seattle Fault 6. Foundations on Peat6. Foundations on Peat 7. Rock Slope Stability Problems in I-907. Rock Slope Stability Problems in I-90 8. Fracture Image Logging Technologies8. Fracture Image Logging Technologies 9. Tunneling for Sound Transit9. Tunneling for Sound Transit 10. Engineering Properties of Organic Soils in the Puget Sound 10. Engineering Properties of Organic Soils in the Puget Sound

AreaArea 11. Engineering Properties of Glacial Soils in the Puget Sound 11. Engineering Properties of Glacial Soils in the Puget Sound

Area 12. Solute Transport in Fractured Rock 13. Economic Area 12. Solute Transport in Fractured Rock 13. Economic Minerals of Washington State 14. Quarry Mines of Puget SoundMinerals of Washington State 14. Quarry Mines of Puget Sound

15. Failure of Malpassat Dam15. Failure of Malpassat Dam 16. Rock Tunnel Failures in the Alps16. Rock Tunnel Failures in the Alps 17. Seattle Watershed Geology17. Seattle Watershed Geology

Grad RequirementsGrad Requirements Add Goodman – Engineer as Artist Add Goodman – Engineer as Artist

(unless discuss with us otherwise)(unless discuss with us otherwise)

Paper and Paper TopicsPaper and Paper Topics Paper I TopicsPaper I Topics Columbia River Basalts – Origin, Columbia River Basalts – Origin,

Structure, Hydrologic and Structure, Hydrologic and Engineering PropertiesEngineering Properties

Geology and Engineering Geology of Geology and Engineering Geology of the Snoqualmie Pass Quadranglethe Snoqualmie Pass Quadrangle

Clay Minerals – Origin, Crystal Clay Minerals – Origin, Crystal Structure, Engineering PropertiesStructure, Engineering Properties

6 Pages, 1.5 space, plus figures, 6 Pages, 1.5 space, plus figures, include references.include references.

CEE 437 Syllabus, Rev.2006-10-3

Week Day Date Lecturer Quiz Paper LectureStudy Guide

Textbook -West

1 Thu 28-Sep Doe Overview: Earth as an Engineering Material Ch. 1

2 Tue 3-Oct DoePlate tectonics, rock cycle, mineral introduction Ch 1

2 Thu 5-Oct Doe Minerals Continued, Clays, Minerals Lab Ch 2

3 Tue 10-Oct Doe x Igneous and Metamorphic Rocks3 Thu 12-Oct Doe Sedimentary Rocks, Rock Lab Ch 3, 5

4 Tue 17-Oct DoeGeologic Time; Structural Geology I Ch 9, 10

4 Thu 19-Oct Doe xStructural Geology II Field Trip Overview, Geologic Maps Ch. 10

5 Tue 24-Oct Dershowitz Rock Mass Classification Ch 10

5 Thu 26-Oct WestGeologic Aspects of Seismic Events Ch 18

Field Trip - Cascades Geology

Field Trip - Cascades Geology

1

2

Sun 29-Oct x

Sun 22-Oct x