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MetamorphicRocks S=slide S1 Metamorphismisthetransformationofonerocktypeintoanother Metamorphicrocksareproducedfromigneous,sedimentary,andmetamorphicrock Parentrock­therockfromwhichitwasformed S2 FoldedandMetamorphosedrockfromtheAnzaBorregoDesert S3 Metamorphism­changeform Processthatleadstochangesinthemineralogy,texture,andsometimeschemical composition Occurswherethepreexistingrockissubjectedtoaphysicalorchemical environmentthatissignificantlydifferentfromwhereitformed temperature pressure(stress) introductionofchemicallyreactivefluids S4 ExampleofLowGradeMetamorphism Fromshale toslate S5 HighGradeMetamorphism Identityofparentisdifficulttodetermineandcannotbedonewithahandsample alone Temperaturesmayapproachthoseatwhichrocksmelt Duringmetamorphismrocksremainessentiallysolid S6 Temperatures,pressures,anddepthsatwhichmetamorphismoccurs Lowgrade­slightchangesmetamorphismoccursatlowTandP. Highgrade­substantialchanges metamorphismoccursathighTandP. S7 HeatasaMetamorphicAgent

Heatprovidestheenergytodrivechemicalreactions­recrystallizationofminerals ornewminerals claysandchemicalprecipitates higherheatleadstochangeinmineral stabilityranges Heatsource­radioactivedecayandresidualheatfromformationofEarth­ geothermalgradient S8 Variationsincrustalgeothermalgradientsindifferentsettingsnearthesurface. About200degreesCclaymineralsbegintorecrystallize­Quartzandfeldspar stable S9 EstimatedtemperatureincreasewithdepthwithinEarth(geothermalgradient). S10 Rockscarriedtogreatdepthoccuratconvergentboundariesandtheycanbedeeply buriedinlargebasinswheregradualsubsidenceresultsinthickaccumulationsof sediment. Heatcanbetransferredbyigneousintrusions S11 ConfiningPressureandDifferentialStress Confiningpressure­forcesareequalinalldirections­deepertherockthegreater thepressure Pressuremaycausemineralstorecrystallizewithmorecompactstructure Differentialpressure­stressesaregreaterinonedirection­rocksshortenedin directionofgreateststressandelongatedindirectionperpendiculartothatstress S12 Confiningpressure­suchastheGulfofMexico­MississippiRiverdeposits sedimentinlayers­bottomlayersareconfinedinalldirections S13 Differentialstressconvergentboundaries­rocksarefoldedandflattenedatdepth wheretherockisductile(canflowduetoheat)andtherockbreaksnearthesurface whereitisbrittleandcolder. S14 Distributionintheupper30kmofEarth'scrustofmetamorphicrocksproducedby regionalandassociatedcontactmetamorphism. S15 Increasingtemperature>expansionbondsspreadoutorbreak

Increasingpressure>compressionbondsarecompressedorbreak. S16 ChemicallyActiveFluids Fluidsarewater,CO2,andvolatiles­fromporespaces,latestageigneous,and hydratedminerals Fluidssurroundmineralgrainsandactascatalyststopromoterecrystallization thoughionmigration(diffusion) Hotterenvironmentsmorereactive MetasomatismFluidfromplutonsreactswithhostrock S17 Solidstatechanges,bondsbreakandreform,ionsmovebydiffusion S18 MetamorphicTextures Texture­size,shape,andarrangementofgrainsinarock Foliation­planar(nearlyflat)arrangementofmineralgrainsorstructuralfeatures inarock Compressionalstressesshortenrockunits­mineralgrainsdevelopparallel,or nearlyparallel,alignments S19 DevelopmentofFoliation 1.Rotationofplaty(i.e.,clayormica)and/orelongated(i.e.,pyroxene)intoanew orientation 2.Recrystallizationofmineralstoformnewgrainsgrowinginthedirectionof preferredorientation(i.e.,claytomicaorchlorite) 3.Changingshapeofequidimensionalgrainsintoelongatedshapesthatarealigned inapreferredorientation S20 FoliatedTextures Slatycleavagecloselyspaceplanarsurfaceswheretherocksplitintothinsheets Schistositymicaandchloritegrainsarelargeenoughtobeseenwithunaidedeye Gneissictexturebandedappearance S21 Differentialstressperdindiculartobeddingcausedtheplatygrainsinshaleand relatedrockstobendintomicrofoldswherethesidesofthefoldarealigned. S22 OtherTextures

Nonfoliated­minimaldeformationand/ortheparentrockiscomposedofall equidimensionalmineralssuchascalciteorquartz Porphyroblastictexture­largegrainsaresurroundedbyafinegrainedmatrix­the largegrainsarecalledporphyroblasts (garnet,stauralite,andalusite) S23 Muscoviteschistwithporphyroblastsofgarnet S24 Tourmalinequartzite,withporphyroblastictexture. S25 metaconglomerate:composedofformerpebblesthathavebeenstretched, deformed,andfused S26 FoliatedRocks Slate­finegrainedfoliatedrockcomposedofminutemicagrains­parentrocks: shale,mudstone,siltstone,orvolcanicash Phyllite­intermediatebetweenslateandschist Schist­mediumtocoarsegrainedrockwhereplatymineralspredominateandmay haveotherminerals,accessorymineralscanbegarnet,stauralite,sillimanite Gneiss­mediumtocoarsegrainedbandedrockwithgranularandelongated minerals,commonmineralsincludequartzandplagioclase,andincludesomemicas, andamphiboles,parentrocksameasaboveandgranite S27 Slate. Formsbylowgrademetamorphismofmudstones,shales,andclaystones. S28 Muscoviteschist. Formsbyintermediategrademetamorphismofphyllite. S29 schist:acoarsegrained,foliatedrockdominatedbymicaoramphibole. S30 Gneissesaremediumtocoarsegrainedbandedmetamorphicrocks Composedofgranularandelongatedminerals Canhaveaccessorymineralssuchasgarnet­garnetgneissor

amphiboleamphibolite S31 gneiss:acoarsegrained,foliatedrockcomposedoffeldspar,quartz,mica,and amphibole. S32 NonfoliatedRocks Nonfoliation­grainsareequidimensional marble­coarse,crystallinemetamorphicrock­parentwasa limestone,canhaveaccessoryminerals quartzite­coarsegrainedmetamorphicrock­parentwasa quartzsandstone hornfels­contactmetamorphismofanyrock serpetinite­parentisbasalt anthracite­parentiscoal S33 marble:acoarsetofinegrained,nonfoliatedrockcomposedmainlyofcalciteor dolomite. S34 Marble. Formsbyintermediatetohighgrademetamorphismoflimestoneordolostone. S35 Quartzite. Formsbymetamorphismofquartzsandstone. S36 quartzite:acoarsegrained,nonfoliatedrockcomposedmainlyofquartz. S37 Hornfels. Formsbycontactmetamorphismofanyrocktype. S38 Serpentinitewithasbestos. S39 Anthracitecoal. Formsbylowtointermediategrademetamorphismofbituminouscoal. S40 MetamorphicEnvironments 1.Contactorthermalmetamorphism

2.Hydrothermalmetamorphism 3.Burialandsubductionzonemetamorphism 4.Regionalmetamorphism 5.Impactmetamorphism 6.Cataclasticmetamorphism­alongfaults Thereisoverlapovermostofthesetypes S41 Thefivetypesofmetamorphismandthesettingswheretheyoccur. S42 MetamorphicEnvironments ContactorThermalMetamorphism Hostrockaroundigneousrockis`baked'oraltered­zoneiscalledanaureole Sizeofaureoledependsonsizeoftheintrusion­smallornarrowintrusionshave verynarrowaureolesandbatholithshavelargeaureoles Compositionofhostrockandamountofwaterpresentaffectsthesizeoftheaureole S43 Hornfels. Formsbycontactmetamorphismofanyrocktype. Marbleandquartzitecanbeproducedincontactmetamorphismaswell S44 Contactmetamorphismoccursduetoheatingofthecountryrockthatbordersa magmaintrusionorlavaflow. S45 Contactmetamorphisminadolomiticlimestonewithquartzandclayimpurities causedbyagranitepluton. Eachchangeinmineralogyisazoneofmetamorphism S46 Parentrocks,metamorphicgradeandtype,andtheresultingmetamorphicrocks. S47 MetamorphicEnvironment HydrothermalMetamorphism Hotironrichfluidscirculatethroughfissuresandcracksintherock Hydrothermalmetamorphismisachemicalalteration Associatedwithigneousactivity,suchastheemplacementofplutonswhereionsin solutionnotincorporatedintotheplutoncirculatethroughthehostrock alsofoundalongmidoceanridgeswherehotmagmareactswithseawater

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