Download Unit 3 Rocks Ch. 5 Lecture

Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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Unit 3 Chapter 5 How Earth’s Rocks were Formed
HOMEWORK:
HW 1
HW 2
Topic Questions:
PG. 68, 74, 79
Review, Interpret & Apply, Crit. Thinking pg 82-83
Unit 1 Igneous Rocks
Topic 1 Uniformity of Process
Uniformitarianism states, “the present is the key to the past”
1. the geologic processes now at work were also active in the past
2. the present physical features of Earth were formed by these same
processes, at work over long periods of time.
Topic 2 Three Groups of Rocks
ROCKS ARE SINGLE MINERALS OR MIXTURES OF SEVERAL MINERALS THAT MAKE
UP AN ESSENTIAL PART OF THE EARTH'S CRUST.
THE MOST COMMON ROCKS ON EARTH ARE THOSE FORMED FROM THE COOLING
AND SOLIDIFICATION OF LIQUID ROCK, CALLED MAGMA, AND ARE CALLED
IGNEOUS ROCKS.
SEDIMENTARY ROCKS FORM FROM WEATHERED SEDIMENT OF IGNEOUS,
METAMORPHIC, OR OTHER SEDIMENTARY ROCKS THAT ARE CARRIED FROM
ONE PLACE TO ANOTHER, REDEPOSITED, BURIED, AND THEN HARDENED INTO
ROCK.
METAMORPHIC ROCKS FORM FROM PREEXISTING IGNEOUS, SEDIMENTARY, OR
METAMORPHIC ROCKS AS A RESULT OF TEMPERATURE AND PRESSURE
CHANGES.
Topic 3 Recognizing Igneous Rocks
IGNEOUS ROCKS COMPOSE 95 PERCENT BY VOLUME OF THE CRUST OF THE EARTH.
THEY ARE THE PARENT MATERIALS FOR ALL OTHER KINDS OF ROCK.
IGNEOUS ROCKS ARE THOSE THAT HAVE BEEN FORMED BY THE SOLIDIFICATION
OF MOLTEN ROCK MATERIAL (MAGMA).
IF LIQUID ROCK FLOWS OUT ON TO THE SURFACE OF THE EARTH IT IS CALLED
LAVA.
PLUTONIC (INTRUSIVE) ROCKS FORM BELOW THE SURFACE. THEY HAVE DISTINCT
CRYSTALS OR COURSE TEXTURE.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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VOLCANIC (EXTRUSIVE) ROCKS FORM ON THE EARTH'S SURFACE. THEY HAVE
VERY SMALL OR MICROSCOPIC CRYSTALS OR FINE TEXTURE
Topic 4 KINDS OF MAGMA
FELSIC (GRANITIC) MAGMA - THICK, STIFF MAGMA THAT FORMS JUST BELOW THE
CRUST. LIGHT COLORED VISIBLE CRYSTALS DUE TO HIGH FELDSPAR AND
SILICA CONTENT.
MAFIC (BASALTIC) MAGMA - MAGMA THAT ORIGINATES IN THE MANTLE AND
FLOWS READILY FORMING THIN LAYERS, ESPECIALLY ON THE OCEAN FLOOR.
DARK FINE TEXTURED ROCKS DUE TO MAGNESIUM AND IRON (OLIVINE)
CONTENT.
Topic 5 Textures of an Igneous Rock
THE TERM TEXTURE IN IGNEOUS ROCK REFERS TO THE SIZE, SHAPE, AND
ARRANGEMENT OF THE COMPONENT MINERAL GRAINS. (CRYSTALS)
CRYSTAL SIZE DEPENDS ON HOW FAST THE MAGMA (LAVA) COOLS. THE LONGER IT
COOLS, THE LARGER THE CRYSTALS.
INTRUSIVE IGNEOUS ROCKS - ARE GENERALLY COARSE-GRAINED BECAUSE THE
SLOW RATE OF COOLING ALLOWS TIME FOR LARGE CRYSTAL GROWTH.
EXAMPLE: GRANITE
EXTRUSIVE IGNEOUS ROCKS - GENERALLY HAVE VERY SMALL TO NO CRYSTALS
BECAUSE OF RAPID COOLING.
EXAMPLE: BASALT, OBSIDIAN
Topic 6 PORPHYRITIC TEXTURE
PORPHYRIES - ARE ROCKS WITH TWO OR MORE CRYSTAL SIZES DUE TO DIFFERENT
COOLING RATES.
A ROCK HAVING LARGER EARLIER FORMED CRYSTALS THAT ARE SURROUNDED BY
LATER FORMED SMALLER CRYSTALS.
Topic 7 FAMILIES OF IGNEOUS ROCKS
Topic 8 DESCRIPTION OF COMMON IGNEOUS ROCKS
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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GRANITE FAMILY FORMS FROM FELSIC MAGMAS. LIGHT COLORED ORTHOCLASE
AND QUARTZ ARE DOMINANT.
GRANITE IS MADE OF QUARTZ, ORTHOCLASE FELDSPAR, AND MICA.
GRANITE HAS COURSE-GRAIN TEXTURE. (INTRUSIVE)
OBSIDIAN IS VOLCANIC GLASS WITH MICROSCOPIC TEXTURE. ROCK
FORMED WHEN LAVA COOLS IN WATER. VERY HARD.
CONCHOIDAL FRACTURE.
PUMICE IS FORMED FROM FELSIC LAVA THAT HARDENED WHILE STEAM AND
GASES WERE STILL BUBBLING OUT OF IT. (SOMETIMES FLOATS)
GABBRO FAMILY FORMS FROM MAFIC MAGMAS. DARK COLORED
GABBRO IS DARK COLORED, COURSE-GRAIN TEXTURE. (INTRUSIVE)
BASALT GLASS IS A DARK COLORED EQUIVALENT OF OBSIDIAN.
SCORIA IS A DENSER, DARK COLORED EQUIVALENT OF PUMICE (NEVER
FLOATS)
DIORITE FAMILY HAS A COMPOSITION AND COLOR BETWEEN THE GRANITE AND
GABBRO FAMILIES.
DIORITE IS COURSE GRAINED.
ANDESITE IS FINE GRAINED.
Unit 2 SEDIMENTARY ROCKS
SEDIMENTARY ROCKS COVER 75 PERCENT OF THE SURFACE OF THE EARTH, YET
MAKE UP ONLY 8 PERCENT OF THE VOLUME OF THE EARTH'S CRUST. (UPPER 2
MI, IGNEOUS 15 MI)
TOPIC 10 HOW CLASTIC ROCKS FORM
WEATHERING - THE PROCESSES BY WHICH ROCKS ARE PHYSICALLY BROKEN INTO
SMALLER PARTICLES AND CHEMICALLY DECOMPOSED. (CHANGE)
TWO PROCESSES:
DISINTEGRATION - THE PHYSICAL DISINTEGRATION OR BREAKING OF SOLID
MASSES OF ROCK INTO LOOSE SMALLER FRAGMENTS. THERE IS NO
CHEMICAL CHANGE IN THE ROCK.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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ROCKS ARE BROKEN INTO FRAGMENTS BY:
1. PLANTS AND THEIR ROOTS.
2. PERIODIC FREEZING OF WATER (ICE WEDGING). WATER EXPANDS BY
ABOUT 9 % WHEN IT FREEZES AND IS CAPABLE OF EXERTING THOUSANDS OF
POUNDS OF PRESSURE PER SQUARE INCH.
3. SHEETING - IS A PROCESS IN IGNEOUS ROCKS (GRANITE) WHERE THE ROCK
EXPANDS FORMING CRACKS PARALLEL TO THE SURFACE AFTER ROCK
MATERIAL HAS BEEN REMOVED FROM ABOVE.
DECOMPOSITION - THE CHEMICAL SEPARATION OF MINERALS AND ROCKS INTO
ELEMENTS OR SIMPLER COMPOUNDS.
RAINWATER CONTAINS CARBON DIOXIDE WHICH FORMS CARBONIC ACID.
SULFUR AND NITROGEN IN THE AIR FORMS SULFURIC AND NITRIC ACIDS
(ACID RAIN)
DECAYING ORGANIC MATTER FORMS HUMIC ACID IN THE SOIL.
TOPIC 11 SORTING OF SEDIMENTS
EROSION - IS THE PROCESS BY WHICH WEATHERING PRODUCTS ARE CARRIED
AWAY (TRANSPORTED) AND REDEPOSITED BY WIND, WATER, GRAVITY, OR
ICE.
AS WIND AND WATER SLOW DOWN, THEY LOOSE (KINETIC) ENERGY TO CARRY
MATERIAL.
THEY WILL DROP THE HEAVIEST PARTICLES (ROCKS) FIRST AND NEXT HEAVIEST
PARTICLES SECOND (SAND) AND THE LIGHTEST PARTICLES LAST (SILT AND
CLAY).
THIS RESULTS IN SORTING OF ERODED SEDIMENT BY SIZE OR MASS.
TOPIC 9 KINDS OF SEDIMENT
SEDIMENT - SMALL PARTICLES BROKEN DOWN FORM SOLID ROCK. SEDIMENTS
MAY CONSIST OF FRAGMENTS OF IGNEOUS, METAMORPHIC, OR OLDER
SEDIMENTARY ROCKS.
SEDIMENTARY ROCKS ARE IDENTIFIED AND NAMED ACCORDING TO THEIR
COMPOSITION AND TEXTURE.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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TWO GENERAL TYPES OF SEDIMENTARY ROCK:
CLASTICS - ARE ROCKS COMPOSED OF PARTICLES OF CLAY, SILT, SAND, AND
GRAVEL, OR FRAGMENTS OF PARENT ROCK OR FOSSILS.
CLASTIC ROCKS ARE NAMED ACCORDING TO THE SIZE AND SHAPE OF THE
FRAGMENTS (TOPIC 12 CONGLOMERATE, SANDSTONE, & SHALE
1. CONGLOMERATES - ARE MIXTURES OF ROUNDED PEBBLES OF ANY KIND
OR SHAPE.
2. BRECCIA - SIMILAR TO CONGLOMERATES EXCEPT FRAGMENTS ARE SHARP
ANGULAR PIECES.
3. SANDSTONES - USUALLY CONSIST OF SMALL QUARTZ GRAINS, BUT MAY BE
COMPOSED OF CALCITE, FELDSPAR OR OTHER MINERAL FRAGMENTS.
(.2 TO 2 mm)
4. SILTSTONE - IS LIKE STANDSTONE BUT WITH SMALLER GRAINS THAT CAN
BE FELT BUT ONLY SEEN WITH MAGNIFICATION. (.005 TO .1 mm)
5. SHALE - IS MADE OF THIN LAYERS OF CLAY AND MUD TOO SMALL TO BE
SEEN WITHOUT MAGNIFICATION. ( < .004 mm) FORMED BY COMPACTION
ALONE.
ALL CLASTIC ROCKS UNDERGO SOME KIND OF CONSOLIDATION PROCESS
(LITHIFICATION)
THE PROCESS OF CONVERTING SEDIMENT INTO SEDIMENTARY ROCK IS CALLED
LITHIFICATION AND INVOLVES CEMENTATION AND COMPACTION.
CEMENTATION - THE PROCESS WHICH INVOLVES THE PRECIPITATION OF MINERALS
IN THE PORE SPACES BETWEEN PARTICLES OF THE SEDIMENT.
THE PRECIPITATION, CALLED CEMENT, IS MOST OFTEN EITHER CALCITE (CaCO3) OR
SILICA (SiO2).
COMPACTION - A PROCESS BY WHICH SEDIMENTS
IMPERMEABLE - FLUIDS ARE NOT ABLE TO MOVE THROUGH IT. (SHALE)
PERMEABLE (POROUS) - LIQUID CAN MOVE THROUGH. OIL OR WATER MAY
ACCUMULATE IN PORE SPACES IN THESE ROCKS. (SANDSTONE)
NONCLASTIC ROCKS FORM BY CHEMICAL OR BIOCHEMICAL (ORGANIC)
PRECIPITATION. (FROM SOLUTION) (TOPIC 9)
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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TOPIC 13 SEDIMENTARY ROCKS OF CHEMICAL ORIGIN
PRECIPITATES - OCCUR WHEN CHEMICAL REACTIONS FORM A SOLID THAT
SETTLES OUT OF SOLUTION. (CALCITE CRYSTALS IN CAVES)
1. LIMESTONE - COMPOSED OF CALCITE; MOST ASSOCIATED WITH SEAS AND
BIOLOGICAL PROCESSES OF CORALS AND OTHER MARINE ORGANISMS.
2. CHALK - IS A VARIETY OF LIMESTONE CONSISTING OF CALCITE AND
SHELLS (MICROSCOPICALLY SMALL)
3. FLINT OR CHERT - COMPOSED OF SILICA; AND THOUGHT TO HAVE FORMED
FROM ACCUMULATIONS OF SILICEOUS REMAINS OF DIATOMS AND
RADIOLARIA.
EVAPORATES - FORM WHEN WATER EVAPORATES, LEAVING ITS DISSOLVED SOLIDS
BEHIND. (BEDS OF SALT AND GYPSUM)
4. ROCK SALT - COMPOSED OF HALITE; FORMED AS A RESULT OF THE
EVAPORATION OF SALINE WATER BODIES.
5. ALABASTER - GYPSUM; FORMED BY EVAPORATION.
TOPIC 14 SEDIMENTARY ROCKS OF ORGANIC ORIGIN
6. COAL - RESULTS FROM THE ACCUMULATION OF PLANT MATTER IN SWAMPY
ENVIRONMENTS AND THEN BIOCHEMICALLY AND PHYSICALLY
CONSOLIDATED INTO A CARBON RICH MATERIAL.
BITUMINOUS - SOFT COAL
ANTHRACITE - HARD COAL
ORGANIC DEPOSITS RESULT FROM LIFE PROCESSES.
TOPIC 15 SEDIMENTARY FEATURES
THE ENVIRONMENT OF DEPOSITION IS THE LOCATION WHERE SEDIMENT IS BEING
DEPOSITED.
THE THREE MAJOR ENVIRONMENTS OF DEPOSITION ARE THE MARINE,
CONTINENTAL, AND TRANSITIONAL ENVIRONMENTS.
COMPARING PRESENT-DAY SEDIMENTARY DEPOSITS TO OLD SEDIMENTARY ROCKS
PERMITS ONE TO RECONSTRUCT CONDITIONS OF THE EARTH AS THEY WERE
HUNDREDS OF MILLIONS OF YEARS AGO.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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UNIFORMITARIANISM - (HUTTON) GEOLOGICAL PRINCIPLE THAT STATES THAT
GEOLOGICAL PROCESSES OF THE PRESENT ARE SIMILAR TO PROCESSES OF
THE PAST. (EROSION)
SEDIMENTS AND THUS SEDIMENTARY ROCK ARE DEPOSITED IN LAYERS. THE
OLDEST BED (LAYER) IS DEPOSITED FIRST AT THE BOTTOM OF THE SERIES OF
LAYERS. (LAW OF SUPERPOSITION)
SEDIMENT WILL BE DEPOSITED WHENEVER THERE IS INSUFFICIENT ENERGY TO
CARRY IT FURTHER.
CROSS-BEDDING IS AN ARRANGEMENT OF BEDS IN WHICH ONE SET OF LAYERS IS
INCLINED RELATIVE TO THE OTHERS. OFTEN INDICATIVE OF PASS CHANGES
IN WIND OR WATER CURRENTS.
TOPIC 16 FOSSILS IN SEDIMENTARY ROCKS
FOSSIL - IS ANY RECORD (FOSSILIZED OR IMPRESSIONS) OF PAST LIFE SUCH AS A
BONE, SHELL, OR OTHER HARD PART OF AN ANIMAL OR PLANT.
TOPIC 17 RIPPLE MARKS AND MUD CRACKS
RIPPLE MARKS - ARE COMMON FEATURES THAT FORM ON DUNES OR ON BEACHES
AND ARE USEFUL IN INDICATING WIND OR WATER CURRENTS AND THE TOPS
OF STRATA. FORMED BY THE PROCESS OF CEMENTATION.
MUD CRACKS - FORM ALONG SHORES OR IN RIVER BEDS. THEY DEVELOP WHEN
FINE-GRAINED SEDIMENTS SHRINK ON DRYING, SAND IS BLOWN IN TO
CRACKS, THEN CONSOLIDATED.
TOPIC 18 NODULES, CONCRETIONS, GEODES
CONCRETIONS - ARE BALL-LIKE OBJECTS OR IRREGULARLY SHAPED MASSES OF
CEMENTING MATERIAL COLLECTED AROUND A NUCLEUS OF BONE OR OTHER
FOSSILIZED MATERIAL, A MUDBALL, OR A MASS OF SANDSTONE.
GEODES - ARE HOLLOW, BALL-LIKE OBJECTS SOMETIMES FOUND IN LIMESTONE.
QUARTZ AND OTHER MINERAL CRYSTALS GROW INWARD FROM A HARD
OUTER RIM OF SILICA.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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Unit 3 METAMORPHIC ROCKS
TOPIC 10 WHAT METAMORPHIC ROCKS ARE
METAMORPHIC ROCKS - FORM FROM PRE-EXISTING IGNEOUS, SEDIMENTARY, OR
METAMORPHIC ROCKS AS A RESULT OF TEMPERATURE AND PRESSURE AND
ASSOCIATED CHEMICAL SOLUTIONS.
METAMORPHIC ROCKS ARE THE LEAST ABUNDANT OF THE THREE ROCK CLASSES.
THREE CHANGES OCCUR AS THE RESULT OF METAMORPHISM:
1 A REARRANGEMENT OF MINERAL GRAINS
FOLIATION - IS THE ARRANGING OF ROCKS INTO LAYERS TO OCCUPY
THE LEAST POSSIBLE SPACE. FOLIATION IS PRIMARILY THE RESULT
OF DYNAMIC (PRESSURE) METAMORPHISM.
2 RECRYSTALLIZATION - OR ENLARGEMENT OF CRYSTALS
3 A CHANGE IN THE CHEMISTRY OF THE ROCK THAT RESULTS IN
RECOMBINATION OF ELEMENTS TO FORM DIFFERENT MINERALS.
METASOMATISM - IS THE GROWTH OF NEW MINERALS (CHEMICAL
CHANGES) DUE TO AN EXCHANGE OF IONS BETWEEN THE ORIGINAL
ROCK AND HIGH TEMPERATURE FLUIDS MOVING THROUGH THE ROCK.
TYPES OF METAMORPHISM
TOPIC 20 REGIONAL METAMORPHISM
REGIONAL METAMORPHISM - METAMORPHISM OVER EXTENSIVE AREAS AS A
RESULT OF INTENSE COMPRESSION ASSOCIATED WITH THE CONVERGENCE OF
TECTONIC PLATES DURING MOUNTAIN BUILDING. (12 - 15 km)
METAMORPHISM ASSOCIATED WITH MOUNTAIN BUILDING DECREASES IN
RANK (SEVERITY) OUTWARD FROM THE MOUNTAIN CORE.
BURIAL METAMORPHISM - CHANGES OCCUR DUE TO THE WEIGHT OF OVERLYING
ROCK WHICH CAUSES REORIENTATION OF MINERAL GRAINS WITHIN THE
ROCK. (12 - 15 km)
TOPIC 22 CONTACT METAMORPHISM
CONTACT METAMORPHISM - OCCURS AT OR NEAR THE CONTACTS BETWEEN HOT
IGNEOUS MATERIAL AND COUNTRY ROCK. HEAT IS THE MOST IMPORTANT
AGENT IN CONTACT METAMORPHISM. W/IN 2 km.
IN VARYING AMOUNTS, LIQUIDS AND GASES ARE ALWAYS PRESENT AND REACT
WITH ELEMENTS IN THE COUNTRY ROCK.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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UNUSUAL MINERALS ARE FOUND AT THE CONTACT ZONE.
TWO GENERAL GROUPS OF METAMORPHIC ROCKS:
FOLIATED ROCKS - INCLUDE ROCKS WITH MINERALS ALIGNED IN BANDS.
SLATE - IS A PRODUCT OF REGIONAL METAMORPHISM OF CLAYEY ROCKS,
PARTICULARLY SHALE. REPRESENT THE LOWEST RANK OF METAMORPHIC
ROCKS, THUS LITTLE LAYERING (TOPIC 21 THE METAMORPHISM OF SHALE)
SCHISTS - ROCKS IN WHICH RECRYSTALLIZATION HAS OCCURRED FORMING
LAYERS (FOLIATION) OF BIOTITE, FELDSPAR AND QUARTZ.
SCHISTS ARE THE MOST ABUNDANT METAMORPHIC ROCKS AND ARE ASSOCIATED
WITH MEDIUM-GRADE METAMORPHISM.
GNEISS - IS A COARSE-GRAINED COARSELY BANDED METAMORPHIC ROCK THAT
LOOKS LIKE GRANITE. IT HAS ROUGH LAYERING OF BIOTITE AND
REPRESENTS THE MAXIMUM RANK OF METAMORPHISM. (MINERALS HAVE
SEGREGATED)
NONFOLIATED ROCKS - SHOW LITTLE, IF ANY, ORIENTATION OF GRAINS. THEY
HAVE UNDERGONE INTERNAL CHANGES (RECRYSTALLIZATION).
MARBLE - IS A FINE TO COARSELY CRYSTALLINE ROCK COMPOSED OF CALCITE.
LIMESTONE IS THE PARENT ROCK FOR MARBLE. ENLARGEMENT OF CRYSTALS
TAKES PLACE DURING METAMORPHISM.
QUARTZITE - IS A FINE-GRAINED ROCK COMPOSED OF INTERGROWN QUARTZ
GRAINS AND SILICA CEMENT. QUARTZITES ARE DERIVED FROM QUARTZ
SANDSTONE.
BITUMINOUS COAL METAMORPHIZES INTO ANTHRACITE COAL WHICH IN TURN
METAMORPHIZES INTO GRAPHITE AND FINALLY DIAMONDS.
TOPIC 23 THE ROCK CYCLE
THE ROCK CYCLE
EARTH MATERIALS CONSTANTLY CHANGE. SOME CHANGES OCCUR BELOW THE
SURFACE, OTHERS OCCUR AT THE SURFACE. SOME CHANGES ARE THE
RESULT OF CHEMICAL PROCESSES, SOME ARE DUE TO PHYSICAL PROCESSES.
BENEATH THE SURFACE, THE FORCES OF HEAT AND PRESSURE CHANGE ROCKS. ONE
SOURCE OF THIS HEAT AND PRESSURE IS THE MASS OF OVERLYING ROCKS.
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
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ANOTHER HEAT SOURCE RESULTS FROM THE DECAY OF RADIOACTIVE
ELEMENTS IN ROCKS.
THE FOLLOWING FIGURE SHOWS THE CHANGES THAT ROCKS MAY UNDERGO. THESE
CHANGES ARE REFERRED TO AS THE ROCK CYCLE. MATTER FROM THE
EARTH'S CRUST IS CHANGED FROM ONE FORM TO ANOTHER.
ROCK CYCLE DIAGRAM
Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
Extra Notes not included in your text. (not on exam)
METAMORPHIC PROCESSES:
HIGH HEAT AND PRESSURE CAUSE METAMORPHISM
HEAT MAY COME FROM THREE SOURCES:
DECAY FROM RADIOACTIVE ELEMENTS IN THE
MANTLE. AS THE NUCLEUS OF ATOMS CHANGE
INTO OTHER ATOMS. NUCLEAR ENERGY IS
RELEASED AS HEAT. MOST IMPORTANT SOURCE.
FRICTION WHICH OCCURS DURING MOUNTAIN
BUILDING (MAGMA RISING PUSHING COUNTRY
ROCK ASIDE)
HEAT FROM CONTACT WHEN MAGMA INTRUDES
OVERLYING ROCK. THE ROCK IS ALTERED BY
HEAT, SOLUTIONS, AND GASSES FROM THE
MAGMA.
THERMAL METAMORPHISM - INCLUDES CHANGES DUE TO HEAT.
IS TYPICAL OF THERMAL
METAMORPHISM.
DYNAMIC METAMORPHISM - INCLUDES CHANGES CAUSED
PRIMARILY BY PRESSURE (LITHOSTATIC
PRESSURE) FROM BURIAL OR REGIONAL
METAMORPHISM.
TEXTURE - IN METAMORPHIC ROCK REFERS TO THE
SIZE, SHAPE, AND ARRANGEMENT OF GRAINS.
FOLIATED TEXTURE - ARE BANDS OR LAYERS
CAUSED BY PARALLEL ARRANGEMENT OF MINERALS
(MICA GNEISS)
RECRYSTALLIZED TEXTURE - CONSISTS OF LARGE
INTERLOCKING CRYSTALS
12.5 METAMORPHIC ROCK COMPOSITION
QUARTZ, FELDSPAR, AND MICA ARE ALL MINERALS THAT
COMPOSE IGNEOUS ROCKS. THESE SAME MINERALS
ARE AMONG THE MOST ABUNDANT IN METAMORPHIC
ROCKS.
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Earth Science
Unit 3 Chap. 5 Lecture Notes
B. Rife
THESE MINERALS ARE THE SAME BECAUSE THEY ARE
FORMED UNDER SIMILAR CONDITIONS OF
PRESSURE AND TEMPERATURE.
ANDALUSITE, SILLIMANITE, AND KYNITE ARE MINERALS
THAT ONLY OCCUR IN METAMORPHIC ROCKS.
MINERALS FORMED DURING METAMORPHISM DEPEND ON
THE COMPOSITION OF THE ORIGINAL ROCK AND
THE TEMPERATURES AND PRESSURES TO WHICH
THE ROCK IS SUBJECTED.
THE MOST STABLE MINERALS ARE FORMED UNDER LOW
TEMPERATURE AND PRESSURE IN THE
SEDIMENTARY LAYERS NEAR THE SURFACE.
12.6 CLASSIFICATION OF METAMORPHIC ROCKS
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