Some Slides Lack Permission for Reproduction.
These Slides must be deleted before posting as html or pdf!
Metamorphic Rocks
GEOL 101 Lecture 9
2006
JS Kite WVU
What is story behind this rock?
Test 1 Results Posted this Morning athttp://www.geo.wvu.edu/~kite/teaching.html
Test 061111 & 061122: add 9Test 061133 & 061144: add 7
A = >88B = 75 to 87C= 62 to 74D = 50 to 62
F < 50Class Average = 66.83
Diagenesis:
• All Post-Depositional Physical and Chemical Changes in Sediments and Sedimentary Rocks
• Up to 150OC & 1 kb Pressure
Metamorphism:• Mineralogical & Structural Adjustment to Physical & Chemical Conditions
• Over 150oC & 1 Kb Pressure
Agents of Metamorphism
• Pressure• Temperature• Chemically Active Fluids
(Ion-Rich Water or Gasses)
Types of Metamorphism• Regional Metamorphism
♠Greenschist Metamorphism– High Temperature, High Pressure
♣ Blueschist Metamorphism– Low Temperature, High Pressure
• Contact Metamorphism– High Temperature, Low Pressure
• Shock Metamorphism – Very High Instantaneous Pressure
Where Different Types of Metamorphism Occur
Contact: High Temp., Low Pressure
Regional (= Green Schist): High Heat + High Pressure
1 kb 1 kb
Where Different Types of Metamorphism Occur (See Fig. 7.15, Box 7.3 in Plummer et al., 10th ed.)
Green-schistBlue-schist
Contact
Contact MetamorphismChilled Zones and Baked Zones
Hydrothermal Alteration –Source of Ores (Silver, Gold, Lead, Zinc, Tin, etc.)
Metamorphic Fabric
• Granular• Foliation• Lineated
Granular FabricQuartzite
Stress: Force Applied (to a Rock)
Strain: Rock’s Response to Stress
Strain Ellipse
Regional Metamorphism
Granite - Igneous
Uniform Stress
Gneiss - Metamorphic
DifferentialStress
Foliated Fabric
Fig 7.5 in Plummer et al.10th ed., 2005
Foliated Fabric
Foliatio
n Plane
Foliatio
n Plane
Strain: Stretch-Pebble “Conglomerate”
Strain
Stress
Lineated Fabric
Sorry, No Pictures!
Sequences of Regional Metamorphic Rocks**
Shale Granite Sandstone Limestone Slate Gneiss Quartzite Marble Phyllite Gneiss Quartzite Marble Schist Gneiss Quartzite Marble Gneiss Gneiss Quartzite Marble Migmatite Migmatite Migmatite Migmatite Granite Granite Granite Granite Magma Magma Magma Magma
Original Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Melting
** Leave Room For This TableLeave Room For This Table
4 Slate slides not posted pending permission
• To Explore Slate Quarry Photographs, See http://www.slatevalleymuseum.org
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate
Sed Rock
MetamorphicRock
150oC &/or 1 kb
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate’s color varies
Sed Rock
MetamorphicRock
150oC &/or 1 kb
Slate Quarry in Action
Slate in Storage
Jim Covino'sproduction
http://www.slatevalleymuseum.org/images/chips.jpg
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite (note “sheen”)
Sed Rx
Incr
easi
ngM
etam
orph
ism
Picture for 2001?
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite Schist .
Sed Rx
Incr
easi
ngM
etam
orph
ism
Schist in Thin Section
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite Schist Gneiss .
Sed Rx
Incr
easi
ngM
etam
orph
ism
Gneiss in thin section
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite Schist Gneiss Migmatite .
Sed Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Migmatite: Metamorphic Rock that Contains Partially Melted Zones of Igneous Rock
Transitional between Transitional between Metamorphic & IgneousMetamorphic & Igneous
GSNL image
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite Schist Gneiss Migmatite Granite .
Sed Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Granite with Schist Xenolith
GSNL imageGSNL image
Regional Metamorphism of Clay-Rich Sedimentary Rocks
Shale Slate Phyllite Schist Gneiss Migmatite Granite Magma .
Sed Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Melting
Sequences of Regional Metamorphic Rocks
Shale Granite Slate Gneiss Phyllite Gneiss Schist Gneiss Gneiss Gneiss Migmatite Migmatite Granite Granite Magma Magma .
Orig. Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Melting
Sequences of Metamorphic Rocks
Shale Granite Sandstone Slate Gneiss Quartzite Phyllite Gneiss Quartzite Schist Gneiss Quartzite Gneiss Gneiss Quartzite Migmatite Migmatite Migmatite Granite Granite Granite Magma Magma Magma .
Orig. Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Melting
Quartzite in Thin SectionHexagonal Quartz xls
Sequences of Metamorphic Rocks
Shale Granite Sandstone Limestone Slate Gneiss Quartzite Marble Phyllite Gneiss Quartzite Marble Schist Gneiss Quartzite Marble Gneiss Gneiss Quartzite Marble Migmatite Migmatite Migmatite Migmatite Granite Granite Granite Granite Magma Magma Magma Magma .
Orig Rx
Incr
easi
ngM
etam
orph
ism
Partial Melting
Melting
Marble: e.g. Engineering Marble: e.g. Engineering Science Bldg. FoyerScience Bldg. Foyer
ThinSection
Review of Coal Genesis• Plant Fragments • Peat • Lignite• Bituminous Coal• Anthracite Coal
Dia
gene
sis
150oC &/or 1 kbMetamorphism .
Metamorphic Rx from Mafic Igneous Rx
• Greenstone (= Greenschist)• Amphibolite• Serpentinite• Soapstone (Talc + Asbestos) .
Amphibolite
Metamorphic Rx from Mafic Igneous Rx
Index Minerals & Metamorphic Grade for Clay-Rich Rocks
Clays Chlorite Biotite Garnet Staurolite Kyanite Sillimanite
400OC
700OC High Grade
Low Grade
Diagenetic Minerals 150OC
Intermediate Grade
Geologic Map
Aureoles
Name of Rock and Grade
• Comes From HIGHEST Index Mineral Present
• e.g. Staurolite Schist May Have Garnet & Biotite in It .
Isograds: • Lines Separating
Metamorphic Zones
Metamorphic Facies (See Box 7.3, p. 171)
Diagenesis Contact Metamorphism
Regional Metamorphism
PT
Retrograde Metamorphism
• Higher Grade Index Minerals may Break Down to Form Lower Grade Index Minerals
• Requires Chemically Active Fluids &• Long Time at New Temperature &
Pressure .
Porphyroblasts
• Large xls in met. rx• Remember Porphyry (ig. rx)?• Porphyroblasts = Last
Formed Xls .
GSNL image
Staurlolite Porphyroblasts
GSNL image
Augen: Snow-Ball Garnets
GSNL image
Cataclastic Rocks: Mylonite,Friction Breccia (shown below)
GSNL image
Metamorphic Rocks, Continued -Contact Metamorphism
Geology 101 Section 002 Quiz #3 (Due in class (7 oops) 9 February 2006)
• 1. What are minimum temperatures and pressures required for metamorphism of rock?
2. Fill out the following table.
??Dolomite (Same as One of the Above)
Hornfels*Mafic Igneous Rx
Anthracite*Bituminous Coal
Marble*Limestone
Quartzite*Sandstone
Granite: unless heat = extreme
*Granite
Hornfels* * * *Shale
Metam. Rock under Contact Metamorphism
Metamorphic Rock under Regional MetamorphismOriginal Rock
Top Related