metamorphic petrology

1. JPRESENTED BY:-
Jatin Kumar
Class:- M.Sc. (P)
Roll No. :- 10803
DEPARTMENT OF GEOLOGY, GOVERNMENT COLLEGE NARNAUL
UNDER THE GUIDANCE
OF :-
Sh. Jaipal singh
Assistant Professor
and HOD

2. METAMORPHIC ROCK
METAMORPHISM
ROCK CYCLE
PHYSICO-CHEMICAL CONTROLS
 PRESSURE ( STRESS )
 TEMPRATURE/HEAT
 FLUIDS
 BULK ROCK COMPOSTION
 GRADE OF METAMORPHISM
 CONTENT
 REFRENCES

3. Rocks, either,
igneous,
sedimentary, and/or
metamorphic, that
have been changed
in shape, size,
texture, and even
mineralogy, by the
application of heat,
temperature, and
chemically active
fluids.

4.  Process of mineralogical and structural
(textural) changes of rock in the solid
state in response to physical and
chemical condition which differ from
those under which they originated.
All metamorphic rocks were once igneous or Sedimentary

6.  Agents or processes due to the process of
metamorphism takes place are called PHYSICO-
CHEMICAL CONTROLS of metamorphic rock.
i. Pressure ( Stress )
ii. Temprature/Heat
iii. Fluids
iv. Bulk rock compostion

7.  Pressure compacts rocks and can break ionic bonds.
This creates more-compact mineral structures.
SOURCES: -
1) Weight of overlying rocks
deeper in earth
2) At convergent boundaries
3) Alone the fault line.

8.  Pressure, like temperature, also increases with depth
 Pressure on rock causes the spaces between
minerals to close, and you get a more COMPACT
rock with a bigger density.
 Increases in pressure make rocks FLOW instead of
fracture.
Minerals tends to flatten and
elongated.
•This why mountain have folded rocks

9.  Heat causes rocks to expand & mineral bonds
weaken or break. Once broken, they can form
new minerals.
 When buried at a depth of about 8km, clay
minerals are exposed to heats of about 150 to
200 degrees C, which is 300-400 degrees F.
 Minerals become unstable and recrystallize to
form new minerals that ARE stable at that
temperature. But silicates (quartz, etc) are
stable at that temperature, so it takes a lot
more to deform them.

10.  The most important component of metamorphism.
 Provides the energy needed to drive chemical
reactions that cause minerals to crystallize.
 Heat for metamorphism comes from two sources:
 Magma
 Change of Temperature with depth
 Magma will "bake" any rock it comes into contact
with
 Heat increases with depth; about every km down
you go in the crust, the temperature increases 20-
30 degrees Celsius.

11.  Any existing open space between mineral grains in a
rock can potentially contain a fluid.
 This fluid is mostly H2O, but contains dissolved ions.
 The fluid phase is important because chemical
reactions that involve changing a solid mineral into a
new solid mineral can be greatly speeded up by having
dissolved ions transported by the fluid.
 If chemical alteration of the rock takes place as a result
of these fluids, the process is called METASOMATISM.

12.  The ‘bulk rock composition’ is the chemical
composition of a body of rock as a whole, and
not the individual chemical compositions of the
various minerals of which the rock is composed
and the more coarse (larger mineral
components) the minerals are in that rock, then
the larger your sample must be in order to get
a valid bulk composition.
 ‘Bulk’ meaning ‘the whole, rather than the parts’

13.  As the temperature and pressure increases on
a body of rock we say the rock undergoes
prograde metamorphism or that grade of
metamorphism increases.
 The low grade metamorphism takes place at
temperature between above 200° to 320°C and
relatively low pressure.
 The high grade metamorphism takes place at
temperature grater then 320°C and relatively
high pressure.

14. In conclusion, the physio-chemical controls of
metamorphic petrology are critical factors that
influence the development of metamorphism in
rocks. These controls include factors such as
temperature, pressure, fluids, and time. The
interaction of these controls creates a complex
system that leads to the formation of metamorphic
rocks. Understanding these controls is crucial in
determining the extent and evolution of
metamorphism in a given area. Through the study of
petrology, geologists can better understand how
rocks transform and the geological processes that
drive these transformations.

15.  "Metamorphic Petrology: Mineralogical, Field, and
Tectonic Aspects" by Bruce W. D. Yardley
 "Principles of Metamorphic Petrology" by Ron
Vernon
 "Metamorphic Rocks and Their Geodynamic
Significance: A Petrological Handbook" by L. R.
M. Cocks and T. H. Torsvik
 "Introduction to Metamorphic Textures and
Microstructures" by J. R. Ashworth and M. T.
Styles