Metamorphic fabric

7/28/2019 Metamorphic fabric

1/50

Fabrics: Foliation and LineationsThere are both tectonic and primary fabricshere are both tectonic and primary fabrics

Random Fabrics Preferred Orientation

Foliation Lineation


2/50

TectonitesR k ith t ti t t i f b iocks with a penetrative tectonic fabric

L t t it f b i d i t d b t t i-tectonite: fabric dominated by a tectoniclineationS-tectonite: fabric dominated by a tectonic

foliationLS-tectonite: general term for a rock with

both a foliation and a lineationoth a foliation and a lineationLS-tectonite: lineation strongerSL-tectonite: foliation stronger


3/50

Tectonic Foliation


4/50

Cleavage Classification

{Compositional


5/50

Spaced Cleavage


6/50

Disjunctive Foliation


7/50

Pencil Cleavage


8/50

Continuous FabricsAll i l fl tt d t t d i t ll lill minerals flattened or rotated into parallelism


9/50

Continuous FabricsAll i l fl tt d t t d i t ll lill minerals flattened or rotated into parallelism


10/50

Continuous Fabrics

C Fineoarse Fine


11/50

Slaty Cleavage


12/50

Slaty Cleavage Formation ~ 250-350oC


13/50

Phyllitic Cleavage ~ Lower Greenschist facies


14/50

Phyllitic Cleavage and Schistosity ~ greenschist facies


15/50

Phyllitehyllite


16/50

Shistosity ~ middle greenschist facies


17/50

Axial Planar Cleavage


18/50

Fanned Cleavage

Cleavage Early Layer Parallel ShorteningCleavage Perpendicular to Bedding

gRefractionCleavage Perpendicular to Bedding


19/50

Cleavage Refraction


20/50

Cleavagesteeper thanbedding

Beddingeddingsteeper thancleavage


21/50

Crenulation Cleavage


22/50

Crenulation Cleavage


23/50

1 M h i l fl tt i f iHow Foliations Develop

1. Mechanical flattening of grains


24/50

1 M h i l fl tt i f iHow Foliations Develop

1. Mechanical flattening of grains

dissolutionreprecipitation

Rieckes Principle


25/50

1 Mechanically flattening grainsHow Foliations Develop

1. Mechanically flattening grains


26/50

2 R t tiHow Foliations Develop

2. Rotation


27/50

3 CrystallizationHow Foliations Develop

3. Crystallization


28/50

4 T itiHow Foliations Develop

4. Transposition


29/50

4 T itiHow Foliations Develop

4. Transposition


30/50

Differentiated layering

5. Inheritance of layered fabric

Gneissic Banding


31/50

6. Pressure-solution cleavage


32/50

to

oma

gF

lea

iveC

juDs


33/50


34/50


35/50

Disjunctive cleavage spacing is a function of initial clay content


36/50

Lineations


37/50

1. Slickensidesfibrous

grooves


38/50

2. Fold lineation


39/50

3. Intersection Lineation


40/50

4. Mineral Lineations

elongate grains


41/50

4. Mineral Lineations

lineation and just a lineationineation andfoliation just a lineation

tabular grains e.g. feldspars


42/50

5. Other Markers

e.g. pebbles, fossils


43/50

5. Other Markers

e.g. reduction spots, ooids, burrows, etc.


44/50

5. Other Markersoblate particles

foliation only


45/50

5. Other Markersprolate particles

lineation or foliation but not both


46/50

6. Boudins


47/50

6. Boudins


48/50

6. Boudins


49/50

6. Boudins


50/50

7. Mullions

Metamorphic fabric

Documents

Transcript of Metamorphic fabric