This document discusses metamorphism and its relationship to plate tectonics. It describes the three types of metamorphism - contact, regional, and dynamic - and explains their association with different plate boundaries. Divergent boundaries experience greenschist facies metamorphism forming metabasalt. Convergent boundaries produce more complex, higher grade metamorphism including blueschist, migmatites, and ophiolites. Transform boundaries result in mylonites and fault breccias through shearing.

2.  INTRODUCTION
 KINDS OF METAMORPHISM
 PLATE TECTONICS
 TYPES OF PLATE BOUNDARIES
 METAMORPHIC FACIES
 DIVERGENT PLATE BOUNDARY
 CONVERGENT PLATE BOUNDARY
 TRANSFORM PLATE BOUNDARY
 CONCLUSION
 REFERENCES

3.  Metamorphism means change.
 The change of minerals or
texture in pre-existing rocks.
 Metamorphic changes occur in
the solid state in the presence of
usually minor amounts of
aqueous or carbonic fluids.
 Metamorphism typically occurs
between diagenesis 200°C and
melting 850°C.

4.  Three kinds of metamorphism exist: contact, dynamic and
regional.
 Regional or Barrovian metamorphism covers large areas of
continental crust typically associated with mountain ranges.
 Contact metamorphism is a result of the temperature increase
caused by the intrusion of magma into cooler country rock.
 Dynamic metamorphism is associated with zones of high to
moderate strain such as fault zones.

6.  Plate tectonics is a scientific theory that describes the large-scale
motions of earth's lithosphere.
 The model builds on the concepts of continental drift, developed
during the first few decades of the 20th century.
 Tectonic plates are composed of oceanic lithosphere and thicker
continental lithosphere, each topped by its own kind of crust.

7.  Three types of plate margins: divergent, convergent and
passive or transform.
 Divergent plate margins are those where two plates move
horizontally away from one another.
 Convergent plate margins are those where two plates of
varying densities move toward each other. The denser plate
descends beneath the lighter plate.
 Passive or Transform plate margins are also known as shear
margins. Two plates slide past each other horizontally.
Types of Plate Boundaries

10.  Low T - Low P : Zeolite
 Mod - High T - Low P : Prehnite-Pumpellyite
 Low T - High P : Blueschist
 Mod to High T - Mod P : Greenschist -
Amphibolite - Granulite
 Mod - High T - High P : Eclogite

11.  Divergent boundaries are
characterized by a rift in the
surface of the earth along the
midocean ridges.
 The ridges are composed of
volcanic mountains that erupt
basalt onto the surface of the
ocean and by that process create
new oceanic crust.
 In this plate margin chemical
action of fluids is the major agent
of change causing
metamorphism.
 Seawater circulates through the
cracks in the hot volcanic rocks,
it is heated to 400° to 450°C.

12.  This hydrothermal water
attempts to equilibrate with
the crust and reacts with
unstable olivine, pyroxene,
and plagioclase to form new
minerals.
 These new minerals are
epidote, sodium-rich
plagioclase, talc, and
serpentine—typical of
greenschist facies
metamorphism.
 The metamorphic rock is
called metabasalt.
Metabasalt

13. An idealized cross section of a midocean ridge

14.  Convergent plate boundaries are
locations where lithospheric
plates are moving towards one
another.
 The plate collisions that occur
in these areas can produce
earthquakes, volcanic activity
and crustal deformation.
 Most metamorphic rocks in the
continents were created at
convergent plate boundaries.
 Near trenches along continental
margins the rock types include
melange, ophiolites and
blueschists.
Ophiolites

15.  In the deeper roots of this magmatic
belt foliated slates, schists and
gneisses are produced.
 In the deeper parts of a mountain
belt, metamorphism can become
intense enough to produce
migmatites
 At subduction zones, two distinctive
types of metamorphic rocks are
juxtaposed to create paired
metamorphic belts.
 The pair consists of an outer and an
inner belt.
Migmatite

16.  The most characteristic
type of metamorphism that
occurs at transform plate
boundaries is caused by the
horizontal shearing motion.
 As the two plates grind
against one another, fault
breccias and fine-grained
mylonites are created.
Mylonite

17.  Metamorphism means change in the rock texture and mineral
composition of a rock.
 Plate tectonics is the scientific theory of large scale plate
movements of the earth.
 Divergent plate margins show greenschist facies
metamorphism and the metamorphic rock is metabasalt.
 Convergent plate margins is a more complex margin including
blueschist facies, ophiolite and higher grade of metamorphism
including migmatites.
 Fine grained mylonites and fault breccias dominate in the
transform plate margins.

18.  Best, Myron G. Igneous and Metamorphic Petrology. New Delhi:
CBS Publishers & Distributors Pvt. Ltd., 1986
 Turner, Francis J. Metamorphic Petrology. 2nd ed. New York:
Hemisphere Publishing Corporation, 1981
 http://earthds.info/pdfs/EDS_19.PDF
 http://earthds.info/pdfs/EDS_20.PDF
 http://earthds.info/pdfs/EDS_21.PDF

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