Igneous Sedimentary Metamorphic. Igneous Sedimentary Metamorphic FIRE.
Introduction to Metamorphic Petrology Recommended Textbook: J.D. Winter (2001) An Introduction to...
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Transcript of Introduction to Metamorphic Petrology Recommended Textbook: J.D. Winter (2001) An Introduction to...
Introduction to Metamorphic Petrology
Recommended Textbook: J.D. Winter (2001) An Introduction to Igneous and Metamorphic Petrology: Prentice Hall Pub.
Scope of Metamorphic petrology
Metamorphic petrology is the study of the subsolidus changes that a rock undergoes when exposed to physicochemical conditions different from those prevailing near the surface of the Earth.
Metamorphism produces changes in mineral assemblages and textures that reflect re-equilibration of the rock to the new physicochemical conditions, i.e., minimization of the energy of the system.
Metamorphism is commonly isochemical (except for volatile components, e.g., H2O, CO2). Where the system is open, the process is referred to as metasomatism.
Metamorphic Reactions
Dehydration
KAl3Si3O10(OH)2 + SiO2 = KAlSi3O8 + AlSi2O5 + H2O
Decarbonation
CaCO3 + SiO2 = CaSiO3 + CO2
Calcite Quartz Wollastonite
Muscovite Quartz K-Feldspar Sillimanite
Solid-Solid
NaAlSi3O8 = NaAlSi2O6 + SiO2
Albite Jadeite Quartz
Metamorphic Facies
A metamorphic facies is a domain of Pressure-Temperature Space
Metamorphic facies are defined by characteristic mineral assemblages specific to particular bulk-rock compositions
Contact or Thermal MetamorphismContact or Thermal Metamorphism Regional MetamorphismRegional Metamorphism
Orogenic MetamorphismOrogenic Metamorphism Burial MetamorphismBurial Metamorphism Ocean Floor MetamorphismOcean Floor Metamorphism
Hydrothermal Metamorphism Hydrothermal Metamorphism (Alteration)(Alteration)
ImpactImpact or or ShockShock MetamorphismMetamorphism
Types of Metamorphism
Orogenic Metamorphism and differential stressOrogenic Metamorphism and differential stress
11 > > 22 = = 3 3 foliation and no lineation foliation and no lineation
11 = = 22 > > 3 3 lineation and no foliation lineation and no foliation
11 > > 22 > > 3 3 both foliation and lineation both foliation and lineation
1
Foliation (or Cleavage) and Lineation
Metamorphic Index Minerals
(Porphyroblasts)
Staurolite (Fe,Mg)2Al9Si4O23(OH) Garnet
(Fe,Mg)3Al2Si3O12
Cordierite(Mg,Fe)2Al4Si5O18
Metamorphic reactions and metamorphic grade
Muscovite + Quartz = K-feldspar + sillimanite + H2O
SillimaniteQuartz
K-feldspar
Muscovite
Oslo:Oslo: K-Feldspar- Cordierite K-Feldspar- Cordierite Orijärvi:Orijärvi: Biotite-muscovite Biotite-muscovite
2 KMg2 KMg33AlSiAlSi33OO1010(OH)(OH)22 + 6 KAl + 6 KAl22AlSiAlSi33OO1010(OH)(OH)22 (Ms) + 15 SiO (Ms) + 15 SiO22
= 3 Mg= 3 Mg22AlAl44SiSi55OO1818 + 8 KAlSi + 8 KAlSi33OO88 + 8 H + 8 H22OO
Metamorphic Facies and IsogradsMetamorphic Facies and Isograds