Download - 340 c Metamorphis m
![Page 1: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/1.jpg)
Metamorphism
•Changes in Rock Composition or Texture •Due to Heat, Pressure and Action of Fluids
![Page 2: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/2.jpg)
We Do Not Live at “Normal” Conditions
• By the standards of Earth’s interior, we live in a frozen vacuum
• Things that look “abnormal” to us are normal behavior for materials–Solids can flow–Solids can react chemically with each
other–A given material can have several
different atomic structures
![Page 3: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/3.jpg)
Chemical Changes in Rocks
Weathering• At Surface
Diagenesis• Sedimentary Rocks
Metamorphism• Starts about 200 C• Outside range of normal near-surface
conditions
![Page 4: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/4.jpg)
Where Does the Heat Come from?
Uranium and Thorium Other Elements + Lead + Radiation (about 90%)
Potassium-40 Calcium-40 or Argon-40 + Radiation (about 10%)
Possibly some primordial heat (controversial)
![Page 5: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/5.jpg)
Where Does the Pressure Come from? • Air Pressure = 14 P.s.i. (1 Atmosphere or 1 Bar
= 100 kPa) • Pressure Beneath 10 Meters (33 Ft.) Of Water
= 1 Atm. = 1 Bar • Same Pressure Beneath 3.5 m (10 ft.) Of Rock • Pressure in Deepest Part of Ocean = 1000 Bars • Pressure under One Mile of Rock = 500 Bars• 1000 Bars (2 Mi. or 3.5 km Of Rock) = 1
Kilobar (Kb.) = 100 MPa
![Page 6: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/6.jpg)
Pressure Units• 1 Newton (N) = gravitational attraction on
100 grams• One Newton = 7 Fig Newtons• 1 Pascal (Pa) = 1 N/square meter• 1 Pascal = pressure under thin cardboard• One bar = 1 atm = 100 kPa• 1 MPa = 10 bars• 1 GPa = 10 kilobars
![Page 7: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/7.jpg)
Types of Metamorphism
Contact• Around Intrusions or Local Heat Sources
Regional• Usually Accompanied by Deformation
Cataclasis• Shearing and fault zones
Shock• Ultra-high pressures and rapid deformation
![Page 8: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/8.jpg)
What Happens During Metamorphism
Minerals React to Form New Minerals• 2SiO2 + CaMg(CO3) 2 == CaMgSi2O6 + 2CO2
• Quartz + Dolomite == Pyroxene
Minerals Change Form• Al2SiO5 == Al2SiO5
• Andalusite == Kyanite
New Materials Are Added (Metasomatism)• CaMg(SiO2)2 + 2CO2 == CaMg(CO3)2 + 2SiO2
• Pyroxene + CO2 == Dolomite + Quartz
• Minerals in Solution == Ore Bodies
Recrystallization
Cataclasis
![Page 9: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/9.jpg)
Polymorphism
Al2SiO5
• Andalusite • Kyanite • Sillimanite
Ice - 6 high pressure forms
Diamond - Graphite
Calcite - Aragonite
Quartz - • - Tridymite -
Cristobalite (increasing temperature)
• - Coesite - Stishovite (increasing pressure)
![Page 10: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/10.jpg)
Why Don't Rocks "De-metamorphose"?
Reactions Can't Reverse Because Ingredients Lost – 2AlSi2O5(OH) == Al2SiO5 + 3SiO2 + H2O – Clay Mineral == Andalusite + Quartz + Water (Lost)
• An example of carbonate metamorphism: – CaMg(CO3) 2 + 2SiO2 == CaMgSi2O6 +2CO2 – Dolomite + Quartz == Pyroxene + CO2 (Lost)
Reactions "Freeze" Sometimes it Does Happen if Fluids Present• Retrograde Metamorphism• On the surface we call it weathering
![Page 11: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/11.jpg)
FoliationFoliation is a
sheetlike structure that forms when rocks are deformed.
![Page 12: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/12.jpg)
Foliationa. Flattening
b. Grain Rotation
c. Solution
d. New Minerals
e. Partial Melting
f. Shearing
![Page 13: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/13.jpg)
Foliation
In every case, the foliation is:
• In the direction of least resistance
• at right angles to the direction of greatest compression.
![Page 14: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/14.jpg)
Metamorphic Grade -
Degree to Which the Rock Has Changed Composition
• Can Often See Original Bedding • Can Sometimes Even See Deformed Fossils • At High Grades, Rocks Can Often Lose All
Trace of Their Original Appearance
![Page 15: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/15.jpg)
Major Metamorphic Rock Types
Temp C Temp F Coal Limestone Sandstone Basalt Shale Index Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700 Melting Begins
![Page 16: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/16.jpg)
![Page 17: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/17.jpg)
Major Metamorphic Rock Types
Temp C Temp F Coal Limestone Sandstone Basalt Shale Index Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700 Melting Begins
![Page 18: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/18.jpg)
![Page 19: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/19.jpg)
Major Metamorphic Rock Types
Temp C Temp F Coal Limestone Sandstone Basalt Shale Index Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700 Melting Begins
![Page 20: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/20.jpg)
![Page 21: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/21.jpg)
Major Metamorphic Rock Types
Temp C Temp F Coal Limestone Sandstone Basalt Shale Index Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700 Melting Begins
![Page 22: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/22.jpg)
![Page 23: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/23.jpg)
Major Metamorphic Rock Types
Temp C Temp F Coal Limestone Sandstone Basalt Shale Index Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700 Melting Begins
![Page 24: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/24.jpg)
![Page 25: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/25.jpg)
What About Other Rocks?
![Page 26: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/26.jpg)
Metamorphic Facies Depth\Temp 300C 400C 500 C 600 C 700 C 800 C
5 km Zeolite Contact Metamorphism - Andalusite forms
10 km - 3 kb GreenschistChlorite, Biotite form •Slate •Greenstone •Quartzite •Marble
AmphiboliteGarnet, Staurolite, Kyanite form •Schist •Amphibolite •Quartzite •Marble •Gneiss
GranuliteSillimanite formsMuscovite breaks down to K-feldsparPartial Melting •Gneiss
15 km Blueschist
20 km - 6 kb
25 km
30 km - 9 kb
35 km
40 km - 12 kb Not Found Eclogite (Mantle)
![Page 27: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/27.jpg)
Metamorphic Map
![Page 28: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/28.jpg)
Mantle Rocks
![Page 29: 340 c Metamorphis m](https://reader033.vdocuments.site/reader033/viewer/2022042821/55cf8fcf550346703ba0149f/html5/thumbnails/29.jpg)
Metamorphism and Plate Tectonics