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, vesicular vesicular 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 could could be be placed placed in in the the same same position position in in the the flowchart flowchart above above as as gabbro. gabbro. DescribeDescribe twotwodifferencesdifferences between between granite granite and and gabbro. gabbro. [ 1[1]] 7878 The The diagram diagram below below represents represents two two magnified magnified views views showing showing the the arrangement arrangement 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]
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with pressure with
mineral growth mineralgrowth
without pressure without mineral growth growth mineral 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 oror cementedcemented Rock shellshell LimestoneLimestone bioclasticbioclastic MicroscopicMicroscopic toto fragmentsfragments very coarse CHEMICALLYvery coarse AND/OR ORGANICALLY CompactedFORMED SEDIMENTARY ROCKS BioclasticBioclastic Compacted Bituminous coal CarbonCarbon plantplant remainsremains Bituminous coal TEXTURE GRAIN SIZECOMPOSITION COMMENTS ROCK NAME MAP SYMBOL
Halite Rock salt FineSchemeScheme forfor MetamorphicMetamorphic RockRockCrystals IdentificationIdentification from P. 7 of ESRT to Crystalline chemical GRAINGRAIN TYPEGypsum OF Rock gypsum coarse TYPE OF precipitates MAP SYMBOL TEXTURETEXTURE SIZESIZE COMPOSITIONCOMPOSITION METAMORPHISMMETAMORPHISM COMMENTSCOMMENTS ROCK ROCK NAMENAME MAP SYMBOL crystals and evaporites Dolomite Low-grade Dolostone FineFine Low-grade SlateSlate metamorphismmetamorphism ofof shaleshale Crystalline or RegionalRegional Precipitates of biologic Calcite origin or cemented shell Limestone bioclastic Microscopic to (Heat(Heat andand FoliationFoliationfragments surfacessurfaces shinyshiny very coarse pressure fromfrom microscopicmicroscopic micamica PhyllitePhyllite FineFine pressure Compacted Bioclastic increases)increases) crystalscrystals Bituminous coal
FOLIATED Carbon FOLIATED toto plant remains MINERAL MINERAL
ALIGNMENT medium ALIGNMENT medium PlatyPlaty micamica crystalscrystals visiblevisible MICA MICA fromfrom metamorphismmetamorphism ofof clayclay SchistSchist oror feldsparsfeldspars QUARTZ QUARTZ GARNET
SchemeGARNET for Metamorphic Rock Identification FELDSPAR AMPHIBOLE FELDSPAR MediumMedium AMPHIBOLE High-gradeHigh-grade metamorphism;metamorphism; toto mineralmineral typestypes segregatedsegregated GneissGneiss ING GRAIN TYPE OF ING MAP SYMBOL TEXTUREBAND- COMPOSITION COMMENTS ROCK NAME
BAND- coarse into bands coarseSIZE PYROXENE into bands PYROXENE METAMORPHISM
Fine Low-gradeMetamorphism of Slate Fine CarbonCarbon Regional Metamorphism of Anthracite coal Fine Regional metamorphismbituminousbituminous coalcoal of shale Anthracite coal Regional As heat and pressure increases:(Heat and FoliationVariousVarious rocksrockssurfaces changedchanged shiny byby VariousVarious ContactContact from microscopic mica Phyllite FineFineFine minerals pressure heatheat fromfrom nearbynearby HornfelsHornfels minerals increases)(heat)(heat) crystalsmagma/lava FOLIATED to magma/lava MINERAL
ALIGNMENT medium Platy mica crystals visible
MICA fromMetamorphismMetamorphism metamorphism ofof of clay Shale becomes SlateQuartz becomes Phyllite becomes SchistQuartziteSchist becomes Gneiss Quartz orquartzquartz feldspars sandstonesandstone Quartzite FineFine QUARTZ
to GARNET to FELDSPAR Regional Medium AMPHIBOLE Regional High-grade metamorphism; NONFOLIATED NONFOLIATED coarse coarseto CalciteCalcite and/orand/or mineralMetamorphismMetamorphism types segregated ofof Gneiss LAST ING oror MarbleMarble NEXT
BAND- coarse dolomite intolimestone bands or dolostone dolomite PYROXENE limestone or dolostone contactcontact Metamorphism of CoarseCoarseFine CarbonVariousVarious Regional PebblesPebbles maymay bebe distorteddistorted MetaconglomerateMetaconglomerateAnthracite coal mineralsminerals bituminousoror stretchedstretched coal
Various rocks changed by Various Contact Fine minerals heat from nearby Hornfels (heat) magma/lava PhysicalPhysical Setting/EarthSetting/Earth ScienceScience ReferenceReference TablesTables —— 20112011 EditionEdition 77 Metamorphism of Quartz quartz sandstone Quartzite Fine 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 Base your answers to questions 55 and 56 on the graph below, which shows a generalized sequence of rock types that form from original clay deposits at certain depths and temperature conditions within Earth’s interior. Inferred Metamorphism of Shale
Surface of Earth 0 Clay deposits Sedimentary 5 Shale zone
Slate 10
Phyllite 15 (km)
20 Schist Depth Metamorphic 25 zone Gneiss 30 0 200 400 600 800 1000 Temperature (oC)
Key At these temperatures rock melts Boundary between sedimentary zone and metamorphic zone
LAST 55 When clay materials are buried to a depth of 14 kilometers, which type of meta- NEXT morphic rock is normally formed? [1]
56 Explain why gneiss would not form at a depth of 27 kilometers and at a temperature of 800°C. [1]
P.S./E. Sci.–Jan. ’03 [21] [OVER] 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
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 The minerals in Foliated(heat) magma/lava Metamorphic
Metamorphism of rocks can beQuartz determinedquartz by sandstone lookingQuartzite at the Fine to Regional
NONFOLIATED coarse bar graph inCalcite the and/or compositionor Metamorphism of section dolomite limestone or dolostone Marble contact
Coarse Various Pebbles may be distorted Metaconglomerate minerals or stretched LAST NEXT Physical Setting/Earth Science Reference Tables — 2011 Edition 7 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
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 Nonfoliatedto rocks sometimes MINERAL
ALIGNMENT medium Platy mica crystals visible
MICA from metamorphism of clay Schist or feldspars QUARTZ GARNET
indicateFELDSPAR the parent rock 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 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 P. 7 of ESRT
Physical Setting/Earth Science Reference Tables — 2011 Edition 7
LAST NEXT