METAMORPHIC ROCKS BEGIN WHAT IS A METAMORPHIC ROCK? A metamorphic rock is a rock that has been changed by heat and/or pressure without completely melting. LAST NEXT Regional Metamorphism Regional metamorphism usually occurs deep underground where rocks are put under intense pressure or stress causing the rock to deform Regional metamorphism PRESSURE LAST NEXT Contact Metamorphism Contact Metamorphism occurs near magma or lava Contact metamorphism magma LAST NEXT A parent rock is the original rock that changed into a metamorphic rock metamorphic rock parent rock LAST NEXT There are two types of Metamorphic Rocks Foliated Nonfoliated Minerals line Minerals don’t up due to line up metamorphism LAST NEXT BaseBase youryour answersanswers toto questionsquestions 75 75 through through 78 78 on on the the Rock Rock Classification Classification flowchart flowchart shown shown below. below. Letters Letters A, A, B,B,andand CCrepresentrepresent specificspecific rocksrocks inin thisthis classificationclassification scheme. scheme. RockRock ClassificationClassification Flowchart Flowchart RocksRocks SedimentarySedimentary IgneousIgneous MetamorphicMetamorphic ClasticClastic CrystallineCrystalline BioclasticBioclastic ExtrusiveExtrusive IntrusiveIntrusive FoliatedFoliated NonfoliatedNonfoliated RockRock LimestoneLimestone Rock B GabbroGabbro Rock C QuartziteQuartzite RockRock AA saltsalt Rock B Rock C NEXT 7575 Rock Rock AAisis composedcomposed ofof veryvery fine-grainedfine-grained quartz quartz and and feldspar feldspar particles particles 0.005 0.005 centi- centi- metermeter inin diameter.diameter. StateState the the name name of of rock rock A A. [ 1[1]] 7676 Rock Rock BBhashas aa glassy,glassy, vesicularvesicular texture texture and and is is composed composed mainly mainly of of potassium potassium feldspar feldspar andand quartz.quartz. StateState thethe namename of of rock rock B B. [ [11]] 7777 Granite Granite couldcould bebe placedplaced inin thethe samesame positionposition inin thethe flowchartflowchart aboveabove asas gabbro.gabbro. DescribeDescribe twotwodifferencesdifferences between between granite granite and and gabbro. gabbro. [ 1[1]] 7878 The The diagramdiagram belowbelow representsrepresents twotwo magnifiedmagnified viewsviews showingshowing thethe arrangementarrangement of of mineralsminerals beforebefore andand afterafter metamorphism metamorphism of of rock rock C C. .State State the the name name of of rock rock C C. [ 1[]1] Foliated Nonfoliated StressStress StressStress StressStress StressStress pressure MineralMineral ArrangementArrangement RockRock C C Showing Showing Banding Banding BeforeBefore MetamorphismMetamorphism AfterAfter Metamorphism Metamorphism PP.S./E..S./E. Sci.–Aug. Sci.–Aug. ’03 ’03 [19][19] [OVER][OVER] LAST with pressure mineral mineral growth without pressure mineral mineral growth Nonfoliated Foliated LAST NEXT Scheme for Sedimentary Rock Identification INORGANIC LAND-DERIVED SEDIMENTARY ROCKS TEXTURE GRAIN SIZECOMPOSITION COMMENTS ROCK NAME MAP SYMBOL Pebbles, cobbles, Rounded fragments Conglomerate and/or boulders embedded in sand, Mostly silt, and/or clay quartz, Angular fragments Breccia feldspar, and Clastic Sand clay minerals; (0.006 to 0.2 cm) Fine to coarse Sandstone (fragmental) may contain . Silt fragments of . Very fine grain Siltstone . (0.0004 to 0.006 cm) other rocks . and minerals Compact; may split Clay Shale (less than 0.0004 cm) easily CHEMICALLY AND/OR ORGANICALLY FORMED SEDIMENTARY ROCKS TEXTURE GRAIN SIZECOMPOSITION COMMENTS ROCK NAME MAP SYMBOL Halite Rock salt Fine Crystals from to chemical Crystalline Gypsum coarse precipitates Rock gypsum crystals and evaporites Dolomite Dolostone Crystalline or Precipitates of biologic Calcite origin or cemented shell Limestone bioclastic Microscopic to fragments very coarse Bioclastic Compacted Carbon plant remains Bituminous coal P. 7 of ESRT Scheme for Metamorphic Rock Identification GRAIN TYPE OF TEXTURE SIZE COMPOSITION METAMORPHISM COMMENTS ROCK NAME MAP SYMBOL Fine Low-grade Slate metamorphism of shale Regional (Heat and Foliation surfaces shiny from microscopic mica Fine pressure Phyllite increases) crystals FOLIATED to MINERAL ALIGNMENT medium Platy mica crystals visible Foliated MICA from metamorphism of clay Schist or feldspars QUARTZ GARNET FELDSPAR Medium AMPHIBOLE High-grade metamorphism; to mineral types segregated Gneiss ING BAND- coarse into bands PYROXENE Carbon Metamorphism of Fine Regional bituminous coal Anthracite coal Various rocks changed by Various Contact Fine minerals heat from nearby Hornfels (heat) magma/lava Metamorphism of Quartz quartz sandstone Quartzite Fine Nonfoliated to Regional NONFOLIATED coarse Calcite and/or or Metamorphism of dolomite limestone or dolostone Marble contact Coarse Various Pebbles may be distorted Metaconglomerate minerals or stretched Physical Setting/Earth Science Reference Tables — 2011 Edition 7 LAST NEXT Foliation Mineral Alignment minerals line up due to pressure Banding under greater pressure minerals separate into dark and light stripes called bands LAST NEXT Scheme for Sedimentary Rock Identification INORGANIC LAND-DERIVED SEDIMENTARY ROCKS TEXTURE GRAIN SIZECOMPOSITION COMMENTS ROCK NAME MAP SYMBOL Pebbles, cobbles, Rounded fragments Conglomerate and/or boulders embedded in sand, Mostly silt, and/or clay quartz, Angular fragments Breccia feldspar, and Clastic Sand clay minerals; (0.006 to 0.2 cm) Fine to coarse Sandstone (fragmental) may contain . Silt fragments of . Very fine grain Siltstone . (0.0004 to 0.006 cm) other rocks . and minerals Compact; may split Clay Shale (less than 0.0004 cm) easily CHEMICALLY AND/OR ORGANICALLY FORMED SEDIMENTARY ROCKS TEXTURE GRAIN SIZECOMPOSITION COMMENTS ROCK NAME MAP SYMBOL Halite Rock salt Fine Crystals from to chemical Crystalline Gypsum coarse precipitates Rock gypsum crystals and evaporites Dolomite Dolostone Crystalline or Precipitates of biologic Calcite origin or cemented shell Limestone bioclastic Microscopic to fragments very coarse Bioclastic Compacted Mineral Alignment Carbon plant remains Bituminous coal P. 7 of ESRT Scheme for Metamorphic Rock Identification GRAIN TYPE OF TEXTURE SIZE COMPOSITION METAMORPHISM COMMENTS ROCK NAME MAP SYMBOL Fine Low-grade Slate metamorphism of shale Regional (Heat and Foliation surfaces shiny from microscopic mica Fine pressure Phyllite increases) crystals FOLIATED to MINERAL ALIGNMENT medium Platy mica crystals visible MICA from metamorphism of clay Schist or feldspars QUARTZ GARNET FELDSPAR Medium AMPHIBOLE High-grade metamorphism; to mineral types segregated Gneiss ING BAND- coarse into bands PYROXENE Carbon Metamorphism of Fine Regional bituminous coal Anthracite coal Various Various rocks changed by BandingFine Contact heat from nearby Hornfels minerals (heat) magma/lava Metamorphism of Quartz quartz sandstone Quartzite Fine to Regional NONFOLIATED coarse Calcite and/or or Metamorphism of LAST dolomite limestone or dolostone Marble NEXT contact Coarse Various Pebbles may be distorted Metaconglomerate minerals or stretched Physical Setting/Earth Science Reference Tables — 2011 Edition 7 Intensity of Metamorphism Low-Grade Metamorphism Little change to rock High-Grade Metamorphism extreme change to rock LAST NEXT shale LOW-GRADE slate Shale slowly changes into Gneiss phyllite schist gneiss HIGH-GRADE LAST NEXT SchemeScheme forfor SedimentarySedimentary RockRock IdentificationIdentification INORGANICINORGANIC LAND-DERIVEDLAND-DERIVED SEDIMENTARYSEDIMENTARY ROCKSROCKS TEXTURETEXTURE GRAIN GRAIN SIZESIZECOMPOSITIONCOMPOSITION COMMENTS COMMENTS ROCK ROCK NAMENAME MAP MAP SYMBOLSYMBOL Pebbles,Pebbles, cobbles,cobbles, RoundedRounded fragmentsfragments ConglomerateConglomerate and/orand/or bouldersboulders embeddedembedded inin sand,sand, MostlyMostly Angular fragments Breccia silt,silt, and/orand/or clayclay quartz,quartz, Angular fragments Breccia feldspar,feldspar, andand ClasticClastic SandSand clayclay minerals;minerals; FineFine toto coarsecoarse SandstoneSandstone (fragmental) (0.006(0.006 toto 0.20.2 cm)cm) (fragmental) maymay containcontain .. .. .. .. .. SiltSilt fragmentsfragments ofof .. .. .. .. Scheme for SedimentaryVeryVery Rock finefine grainIdentificationgrain SiltstoneSiltstone .. .. .. .. .. (0.0004(0.0004 toto 0.0060.006 cm)cm) otherother rocksrocks .. .. .. .. andand mineralsminerals INORGANIC LAND-DERIVEDCompact; SEDIMENTARY may split ROCKS ClayClay Compact; may split Shale (less than 0.0004 cm) Shale TEXTURE(less GRAINthan 0.0004 SIZE cm) COMPOSITION easilyeasily COMMENTS ROCK NAME MAP SYMBOL CHEMICALLYCHEMICALLY AND/ORAND/OR ORGANICALLYORGANICALLY FORMEDFORMED SEDIMENTARYSEDIMENTARY ROCKSROCKS Pebbles, cobbles, Rounded fragments Conglomerate TEXTURETEXTUREand/or GRAIN GRAIN boulders SIZESIZECOMPOSITIONCOMPOSITION COMMENTS COMMENTS ROCK ROCK NAMENAME MAP MAP SYMBOLSYMBOL embedded in sand, Mostly silt, and/or clay Angular fragments Breccia quartz,HaliteHalite RockRock saltsalt FineFine feldspar, and CrystalsCrystals fromfrom Clastic Sand toto clay minerals; Finechemicalchemical to coarse Sandstone (fragmental)CrystallineCrystalline (0.006 to 0.2 cm) GypsumGypsum Rock gypsum coarsecoarse may contain precipitatesprecipitates Rock gypsum . Silt crystalscrystals fragments of andand evaporitesevaporites . Very fine grain Siltstone . (0.0004 to 0.006 cm) otherDolomiteDolomite rocks DolostoneDolostone . and minerals Clay Compact;Precipitates may of biologic split CrystallineCrystalline oror Precipitates of biologic Shale (less than 0.0004 cm) CalciteCalciteSedimentaryorigineasilyorigin