dr. isiorho, ipfw 1 geology g100 quick review for test #2

Dr. Isiorho, IPFWDr. Isiorho, IPFW 11

Geology G100 Geology G100 Quick review for Test #2Quick review for Test #2


Sedimentation and Sedimentary RocksSedimentation and Sedimentary Rocks

What is a sedimentary rock?What is a sedimentary rock?


SedimentsSediments

Sediments are loose fragments of solid materials- pre-Sediments are loose fragments of solid materials- pre-existing rocks, remains of organisms, and precipitation of existing rocks, remains of organisms, and precipitation of mineralsminerals

Sediment textures- Sediment textures- size, shape, and arrangement size, shape, and arrangement are determined by transportation and depositional processesare determined by transportation and depositional processes

SortingSorting selecting particle based on size, shape and densityselecting particle based on size, shape and density

ShapeShape angular or irregular grains become roundedangular or irregular grains become rounded longer travels lead to more rounding of grainslonger travels lead to more rounding of grains


From Sediments to Sedimentary From Sediments to Sedimentary RocksRocks

Pressure, heat, and underground circulating Pressure, heat, and underground circulating water produce changes in rocks- known as water produce changes in rocks- known as DiagenesisDiagenesis

Lithification- conversion of loose sediments Lithification- conversion of loose sediments into solid sedimentary rocksinto solid sedimentary rocks Compaction- weight of overlying materialsCompaction- weight of overlying materials Cementation- mineral precipitated in pore spacesCementation- mineral precipitated in pore spaces Recrystallization- less stable minerals change to Recrystallization- less stable minerals change to

new stable mineralsnew stable minerals


Sedimentary StructuresSedimentary StructuresPhysical features that reflect condition of deposition Physical features that reflect condition of deposition (how and where?)(how and where?)

Beddings (stratification)Beddings (stratification) sediments in distinct layers- separate depositional environmentssediments in distinct layers- separate depositional environments

Graded beddingsGraded beddings deposition occurs in relatively quiet watersdeposition occurs in relatively quiet waters

Cross beddingCross bedding sedimentary layers at an angle to underlying layerssedimentary layers at an angle to underlying layers

Ripple marksRipple marks small surface ridges- produced by water or windsmall surface ridges- produced by water or wind

Symmetrical & AsymmetricalSymmetrical & Asymmetrical Mud crackMud crack

muddy sediments that dry and contractsmuddy sediments that dry and contracts BioturbationBioturbation

No drawing provided No drawing provided


Classification of Sedimentary RocksClassification of Sedimentary Rocks

Detrital and ChemicalDetrital and Chemical DetritalDetrital-- based on grain sizebased on grain size

MudstoneMudstone- - clay and silt size- constitute > 50% of all clay and silt size- constitute > 50% of all detrital sedimentary rocksdetrital sedimentary rocks

ShaleShale- - clay and silt size particles- parallel layers- fissilityclay and silt size particles- parallel layers- fissility SiltstoneSiltstone- - silt size particlessilt size particles SandstoneSandstone- - quartz arenite, arkose (with ~ 25% feldspar), quartz arenite, arkose (with ~ 25% feldspar),

graywacke (lithic, dark fragments & fines)graywacke (lithic, dark fragments & fines) BrecciaBreccia- - angular gravel size particlesangular gravel size particles ConglomerateConglomerate- - rounded gravel size particlesrounded gravel size particles


Sed. rock Classification contd.Sed. rock Classification contd.

Chemical- organic and inorganicChemical- organic and inorganic Organic- derived from living organism/biogenicOrganic- derived from living organism/biogenic

Limestone and chert- composed of skeletal remains of Limestone and chert- composed of skeletal remains of animalsanimals

coal- carbon rich remains of terrestrial plantscoal- carbon rich remains of terrestrial plants Inorganic Sedimentary RocksInorganic Sedimentary Rocks

Direct precipitation from waterDirect precipitation from water e.g. Limestone, cherte.g. Limestone, chert

Evaporation of saline waterEvaporation of saline water evaporite- gypsum, halite, dolostoneevaporite- gypsum, halite, dolostone


Sedimentary EnvironmentsSedimentary Environments

ContinentalContinental rivers, lakes, caves, desert, glaciers- mostly detritalrivers, lakes, caves, desert, glaciers- mostly detrital

Transitional- coastal- along ocean shoresTransitional- coastal- along ocean shores estuaries and deltasestuaries and deltas

MarineMarine shallow-above continental shelf (< 200m (700’))shallow-above continental shelf (< 200m (700’)) deep- beyond the continental shelfdeep- beyond the continental shelf

Sedimentary FaciesSedimentary Facies- - sediments deposits at the same time but in sediments deposits at the same time but in different environments as a horizontal continuum of distinct rock different environments as a horizontal continuum of distinct rock typetype


Metamorphic RocksMetamorphic Rocks

Altered rocksAltered rocks


DefinitionsDefinitions

Metamorphic rock is formed when existing Metamorphic rock is formed when existing rocks change due to subjection to pressure and rocks change due to subjection to pressure and or temperatureor temperature Any rock can undergo metamorphismAny rock can undergo metamorphism

Metamorphism is the process by which heat, Metamorphism is the process by which heat, pressure, and chemical reactions deep within pressure, and chemical reactions deep within the earth alter the mineral content and or the earth alter the mineral content and or structure of existing rock without melting it structure of existing rock without melting it downdown


What Drives MetamorphismWhat Drives Metamorphism

Heat Heat Accelerate pace of chemical reactionsAccelerate pace of chemical reactions

PressurePressure Lithostatic (confining)- rock becomes smaller and denserLithostatic (confining)- rock becomes smaller and denser Directed- minerals become aligned- FoliationDirected- minerals become aligned- Foliation

Circulating FluidsCirculating Fluids Ions in water- change mineral composition Ions in water- change mineral composition

Parent RocksParent Rocks Original rock’s composition will affect the outcome of Original rock’s composition will affect the outcome of

metamorphismmetamorphism


Types of MetamorphismTypes of Metamorphism ContactContact

Heat is the dominant factorHeat is the dominant factor Area affected generally smaller than regional metarmorphismArea affected generally smaller than regional metarmorphism

Regional are two types with extensive coverageRegional are two types with extensive coverage Burial- occurs in deep sedimentary basins- no plate tectonics Burial- occurs in deep sedimentary basins- no plate tectonics

involvedinvolved Dynamothermal- occurs where converging plates squeeze a rock Dynamothermal- occurs where converging plates squeeze a rock

caught between themcaught between them OthersOthers

Hydrothermal- involves hot water from magmaHydrothermal- involves hot water from magma Fault-zone- rocks grinding past one anotherFault-zone- rocks grinding past one another Shock- meteorites strikeShock- meteorites strike Pyrometamorphism- lightningPyrometamorphism- lightning


Metamorphic Rock TypesMetamorphic Rock Types Foliated- based on type of foliationFoliated- based on type of foliation

Slate- fine grainSlate- fine grain Phyllite- fine grain with sheenPhyllite- fine grain with sheen Schist- has ‘split’ appearanceSchist- has ‘split’ appearance Gneiss- layers/bands of mineralsGneiss- layers/bands of minerals

Non-foliated- based on mineral compositionNon-foliated- based on mineral composition MarbleMarble QuartziteQuartzite HornsfelHornsfel

Mixed RockMixed Rock Migmatite- indicates partial meltingMigmatite- indicates partial melting


Metamorphism Metamorphism Temperature & PressureTemperature & Pressure

Information about degree to which a metamorphic Information about degree to which a metamorphic rock differs from its parent materialrock differs from its parent material

Metamorphic Grade- Metamorphic Grade- low (200-400) slate low (200-400) slate high (500-800) gneisshigh (500-800) gneiss

Index minerals/metamorphic Zones are used to Index minerals/metamorphic Zones are used to determine metamorphic condition of temperature and determine metamorphic condition of temperature and pressurepressure Chlorite, muscovite-low grade (low P/T)Chlorite, muscovite-low grade (low P/T) Garnet, staurolite- intermediateGarnet, staurolite- intermediate Sillimanite- high grade (high P/T)Sillimanite- high grade (high P/T)


How old is the Rock?How old is the Rock?

How can we tell the age of rocks?How can we tell the age of rocks?

GeochronologyGeochronology


GeochronologyGeochronology

Geochronology is the study of time in relation Geochronology is the study of time in relation to earth’s existenceto earth’s existence

Relative DatingRelative Dating Determines how old a rock is in relation to its Determines how old a rock is in relation to its

surroundingsurrounding Numerical Dating (Absolute Age?)Numerical Dating (Absolute Age?)

Determines actual age in yearsDetermines actual age in years


Relative DatingRelative Dating

Relies on Key Principles such asRelies on Key Principles such as UniformitarianismUniformitarianism- - thethe present is key to the pastpresent is key to the past Original horizontalityOriginal horizontality

Sediments deposited in horizontal layersSediments deposited in horizontal layers SuperpositionSuperposition

Youngest rocks are on top (assuming no tectonic activity)Youngest rocks are on top (assuming no tectonic activity) Cross-cutting relationshipsCross-cutting relationships

Cut layer is older than ‘cutting’ rockCut layer is older than ‘cutting’ rock Faunal successionFaunal succession

Organisms succeed one another in recognizable reproducible Organisms succeed one another in recognizable reproducible patternpattern

UnconformityUnconformity Represents a break (gap) in the rock recordRepresents a break (gap) in the rock record


Numerical AgeNumerical Age

Isotope Dating relies on the rate of decay of Isotope Dating relies on the rate of decay of radioactive isotopes within a rockradioactive isotopes within a rock

Radioactive isotopes have nuclei that spontaneously Radioactive isotopes have nuclei that spontaneously decay emitting or capturing a variety of subatomic decay emitting or capturing a variety of subatomic particlesparticles

Decaying radioactive isotope- parent isotopes decay Decaying radioactive isotope- parent isotopes decay to form daughter isotopesto form daughter isotopes

Half-life- is the time it takes for half the atoms of Half-life- is the time it takes for half the atoms of parent isotope to decayparent isotope to decay

Some radioactive isotopes with daughter productsSome radioactive isotopes with daughter products U-238 => Pb-206; K-40 => Ar-40; C-14 => N-14U-238 => Pb-206; K-40 => Ar-40; C-14 => N-14


Factors Affecting Isotope Dating Factors Affecting Isotope Dating ResultsResults

Isotope dating is more useful for igneous rocksIsotope dating is more useful for igneous rocks Clock is set when igneous rock crystallizes locking the radioactive Clock is set when igneous rock crystallizes locking the radioactive

isotopes within its crystal latticeisotopes within its crystal lattice

Rock/Mineral must be a closed systemRock/Mineral must be a closed system Atoms of parent and daughter are still present in rock/mineral being datedAtoms of parent and daughter are still present in rock/mineral being dated

Condition of parent MaterialCondition of parent Material Fracture, weathering and migrating ground waterFracture, weathering and migrating ground water

Age of SubstanceAge of Substance Enough measurable daughter isotope, use appropriate radioactive isotopeEnough measurable daughter isotope, use appropriate radioactive isotope


Other Numerical Dating Other Numerical Dating TechniquesTechniques

Fission TrackFission Track High speed particles emitted during radiation may pass through crystal leaving High speed particles emitted during radiation may pass through crystal leaving

‘tears’ within the crystal- the older the rock, the more fission tracks‘tears’ within the crystal- the older the rock, the more fission tracks Dendrochronology (Tree-Ring dating)Dendrochronology (Tree-Ring dating)

Annual growth ringsAnnual growth rings Varve- deposited layers of lake-bottomVarve- deposited layers of lake-bottom

Paired layers of sedimentsPaired layers of sediments LichenometryLichenometry

Lichens grow at a fairly constant rateLichens grow at a fairly constant rate Cosmogenic isotopesCosmogenic isotopes

Used in dating land featuresUsed in dating land features


Geologic Time ScaleGeologic Time Scale

Contrasting several dating techniques chronicling Contrasting several dating techniques chronicling Earth’s history to produce a geologic Time ScaleEarth’s history to produce a geologic Time Scale

Geologic Time Scale- divided into Eons, Eras, Geologic Time Scale- divided into Eons, Eras, Periods, and EpochesPeriods, and Epoches

Phanerozoic Eon (evidence of life began) divided into Phanerozoic Eon (evidence of life began) divided into three erasthree eras Paleozoic (ancient life) dominated by marine invertebratesPaleozoic (ancient life) dominated by marine invertebrates Mesozoic (middle life) dominated by reptilesMesozoic (middle life) dominated by reptiles Cenozoic (recent life) dominated by mammalsCenozoic (recent life) dominated by mammals


The Earth movesThe Earth moves

It’s not an earthquake…but the earth materialsIt’s not an earthquake…but the earth materials


Mass MovementMass Movement

Process that transports Earth’s materials Process that transports Earth’s materials downslope by the pull of gravity downslope by the pull of gravity Friction, strength, and cohesiveness of materials Friction, strength, and cohesiveness of materials

resist mass movementresist mass movement Angle of slope (sloppiness), water content, lack of Angle of slope (sloppiness), water content, lack of

vegetation, and biological disturbances enhance vegetation, and biological disturbances enhance mass wastingmass wasting


Causes of Mass MovementCauses of Mass Movement

Steepness of SlopeSteepness of Slope Faulting, folding, river cut, glacial, coastal wave create Faulting, folding, river cut, glacial, coastal wave create

steep slopesteep slope Composition of Material either promotes or resists Composition of Material either promotes or resists

mass wastingmass wasting Solid /Unconsolidated Solid /Unconsolidated

Vegetation- lack of which promotes mass wastingVegetation- lack of which promotes mass wasting Water Content- increases weight of material and Water Content- increases weight of material and

reduces friction between planes of weaknessreduces friction between planes of weakness Human/Other DisturbancesHuman/Other Disturbances


Triggers for Mass Movement Triggers for Mass Movement EventsEvents

Natural TriggersNatural Triggers Climatic- torrential rains and snow meltClimatic- torrential rains and snow melt Geologic- earthquakes and volcanic eruptionsGeologic- earthquakes and volcanic eruptions

Human-Induced TriggersHuman-Induced Triggers Oversteeping of slopes- excavationOversteeping of slopes- excavation Overloading- excess water, building, and other Overloading- excess water, building, and other

constructionconstruction Deforestation/overgrazing of vegetationDeforestation/overgrazing of vegetation Loud noise- trains, aircrafts, blastingLoud noise- trains, aircrafts, blasting


Mass Wasting TypesMass Wasting Types

Classification is based on composition and velocityClassification is based on composition and velocity Creep- slowest formCreep- slowest form Slides- move along a plane of weaknessSlides- move along a plane of weakness Slumps- move along concave slip surfacesSlumps- move along concave slip surfaces Flows- rocks and soils have with excess waterFlows- rocks and soils have with excess water Falls- fastest type Falls- fastest type

Landslide is a general term for downslope movementLandslide is a general term for downslope movement


Reducing Mass MovementReducing Mass Movement

AvoidingAvoiding Predicting mass movementPredicting mass movement

Terrain analysis, field visit, eye witness/recorded accountsTerrain analysis, field visit, eye witness/recorded accounts Vegetation- over grazing, harvestingVegetation- over grazing, harvesting

PreventingPreventing Develop Prevention PlanDevelop Prevention Plan Enhance Forces that Resist or Reduce forces of mass wastingEnhance Forces that Resist or Reduce forces of mass wasting Structural Approach- reduce slopeStructural Approach- reduce slope Non-Structural Approach- tree, chemical stabilityNon-Structural Approach- tree, chemical stability


Study for Test #2Study for Test #2

Use the class notes/textbook and the links Use the class notes/textbook and the links provided in the syllabus.provided in the syllabus.

It’s an open book test and the “Honor System” It’s an open book test and the “Honor System” prevails…no help from any one, no prevails…no help from any one, no collaborationcollaboration


Some key words for Test #2Some key words for Test #2 Some key words for test #2Some key words for test #2 Cementation, crystallization, Compaction Cementation, crystallization, Compaction Transportation of sediments results in….. Transportation of sediments results in….. Rock salt, sandstone, siltstone, coal, arkose, graywacke Rock salt, sandstone, siltstone, coal, arkose, graywacke Quartzite, marble, slate, schist, migmatite, order of Quartzite, marble, slate, schist, migmatite, order of

metamorphism metamorphism Types of metamorphism, parent materials of some Types of metamorphism, parent materials of some

metamorphic rocks metamorphic rocks Relative age and principles of Superposition, original Relative age and principles of Superposition, original

horizontality, faunal succession, cross-cutting, unconformities, horizontality, faunal succession, cross-cutting, unconformities, radiometric dating, half life.. radiometric dating, half life..

dr. isiorho, ipfw 1 geology g100 quick review for test #2

Documents

sedimentary rocks pressure

grain size detrital

loose sediments

ipfw3 sediments sediments

dolostone slide

muddy sediments

inorganic organic

grain size mudstone