Metamorphic rocks are formed from existing igneous, sedimentary, or prior metamorphic rocks that undergo significant changes due to high heat, pressure, and mineral-rich fluids. They can be categorized into low-grade and high-grade metamorphism, with varied textures including foliated and non-foliated forms, such as slate, schist, gneiss, marble, and quartzite. The main agents of metamorphism include heat, pressure, and chemically active fluids, which drive the transformation and recrystallization of the rocks.

1. METAMOPH
IC
ROCKS
By: Group 3

2. What is Metamorphic rock?
Metamorphic rocks started out as
some other type of rock, but have been
substantially changed from their original
igneous, sedimentary, or earlier
metamorphic form.

3. What is Metamorphic rock?
Metamorphic rocks form when
rocks are subjected to high heat, high
pressure, hot mineral-rich fluids or,
more commonly, some combination of
these factors.

4. Metamorphism is the change in the
mineral’s composition and texture of the
rock when subjected to high temperature
and pressure within the earth; there is
transformation of pre-existing rocks. The
degree of metamorphism is shown in
the rocks texture and mineralogy.

5. Types of
Metamorphism
1.Low-grade ( slight
changes) e.g., shale
becomes slate.
2.High-grade( substantial
changes) causes the
original features to
obliterated.

6. Metamorphic settings
1. Contact or thermal metamorphism takes
place when the rock is intruded by magma.
Here, change is driven by the rise in
temperature within the host rock surrounding a
molten igneous body.

8. Metamorphic settings
2. Regional metamorphism occurs when a
large area is affected due to large-scale heat
and pressure such as mountain building. When
this happens, metamorphism produces a great
volume of metamorphic rocks.

10. Agents of
Metamorphism
They are three (3) agents of
metamorphism, these are: (1) heat, (2)
pressure or stress due to confining pressure
and differential stress during mountain
building, and (3) chemically active fluids
(mainly water and other volatiles) which
promote recrystallization by enhancing ion
migration.

11. Metamorphic textures
When rocks are subjected to low-grade
metamorphism, they become more compact
and thus denser. A common example is the
metamorphic slate. Here some types of
metamorphic textures:

12. 1. Foliated texture results in the
mineral alignment perpendicular to
the compressional force and usually
gives the rock a layered or banded
appearance.

13. Common foliated metamorphic rock:
a. Slate is a finely
grained rock
composed mostly of
mica and produced
through the low-grade
metamorphism of
shale.

14. Common foliated metamorphic rock:
b. Schist (pronounce "shists")
is a strongly foliated rock and
described as platy meaning,
the rock's crystals are thin and
leaf-like". Its types are based
on composition.

15. Common foliated metamorphic rock:
c. Gneiss (pronounced "nice")
is a strong segregation of
silicate minerals and
exhibits a "banded" texture
(alternating layers of light
and dark minerals like
granite.

16. 2. Non-foliated texture contains
equidimensional crystals and
resembles a coarse-grained igneous
rock. Examples of non-foliated rocks
are the following:

17. a. Marble results when limestone
(parent rock) is metamorphosed.
There are large, interlocking
crystals of calcite and is used as a
building stone and has variety of
colors.
Examples of non-foliated rocks

18. b.Quartzite forms from
quartz sandstone
(parent rock); quartz
grains are fused.
Examples of non-foliated rocks