Week 4_Three types of rocks_powerpoint presentation

three types of rocks for senior high school learners

1. Lesson 6: Minerals
and Rocks

2. At the end of the lesson, the learners will be
able to:
• identify and describe the three basic rock
types;
• establish relationships between rock types
and their mode of origin and environments
of deposition/formation; and
• understand the different geologic
processes involved in rock formation.

3. Element Symbol % by wt. of the
Earth’s crust %
atoms
Oxygen O 46.6 62.6
Silicon Si 27.7 21.2
Aluminum Al 8.1 6.5
Iron Fe 5.0 1.0
Calcium Ca 3.6 1.9
Sodium Na 2.8 2.6
Potassium K 2.6 1.4
Magnesium Mg 2.1 1.8
All other elements 1.4 <0.1

4. Approximately 85% of the Earth's
crust is composed of oxygen
and silicon.
Together they form the silicon
oxygen tetrahedron, which is the
basic building block of silicate
minerals.
Silicates are also termed as
(common) rock forming minerals.

5. WHAT IS A MINERAL?

6. Rocks are an aggregate of
minerals.
 A rock can be composed of a
single mineral (e.g. Quartzite is a
metamorphic rock composed
predominantly of Quartz) or
more commonly composed of
an aggregate of two or more
minerals.

7. Can a name of a mineral be
also used as a rock name?

8. Yes
a rock composed predominantly of the
mineral Gypsum (CaSO4) is called
Gypsum Rock.

9. How can we classify rocks?
Would it be by color,
hardness, texture, density or
other physical properties? Is it
by chemical composition?

10. Generally rocks are
classified on the basis of
the mode of formation and
that some of these physical
and chemical properties
are inherent on how the
rocks are formed.

11. WHAT ARE
THE THREE
ROCK
TYPES?

12. IGNEOUS ROCKS
SEDIMENTARY ROCKS
METAMORPHIC ROCKS

13. - these are rocks that are derived from the
cooling and solidification of magma or
lava
- from solidified molten rock materials,
usually hard and crystalline
- rate of cooling as one of the most
important factors that control crystal size
- solidification can occur along the surface
of the earth or beneath the surface of
the earth

14. How is Lava different from Magma?
Magma is a molten rock material
beneath the surface of the earth.
Lava is molten rock material
extruded to the surface of the earth
through a central vent(volcano) or
as fissure eruption.

15. Plutonic or intrusive rocks
- from solidified magma underneath the
earth
- gradual lowering of temperature is
indicated by the movement of magma
from depth to surface causing slow
cooling /crystallization
-Slow cooling forms large interlocking
crystals, a texture called phaneritic.
- Examples: granite, diorite, gabbro

16. Volcanic or Extrusive rocks
- from solidified lava at or near the surface
of the earth
- fast rate of cooling/crystallization due to
huge variance in the temperature
between Earth’s surface and underneath
common textures: aphanitic, porphyritic,
vesicular.

17. Volcanic or Extrusive rocks
*Common textures:
a.) Aphanitic texture: fine-grained texture;
minerals not visible to the naked eye;
relatively fast rates of cooling/
solidification prevent the formation of
large crystals.

18. Volcanic or Extrusive rocks
*Common textures:
b.) Porphyritic texture: formed through two
stages of crystallization where in magma
partly cooled below the surface of the
earth providing time for the large crystals
to grow (phenocrysts) before it is
extruded to the surface forming the
finegrained matrix (groundmass).

19. Volcanic or Extrusive rocks
*Common textures:
c.) Vesicular texture: voids created by
rapid cooling which causes air bubbles to
be trapped inside.

20. Volcanic or Extrusive rocks
- examples: rhyolite, andesite, basalt
- Pyroclastic rocks: fragmental rocks usually
associated with violent or explosive type
of eruption.
Examples tuff and pyroclastic flow deposits
(ignimbrite)

21. Igneous rocks are also classified
according to silica content and relative
amounts of K, Na, Fe, Mg and Ca.
 They can be classified as felsic,
intermediate, mafic and ultramafic,
practically based on presence of light
and dark colored minerals.

22. The relatively dark minerals are
olivine, pyroxene, hornblende
and biotite.
 The relatively light colored
minerals are plagioclases,
Kfeldspars,quartz and muscovite.

23. - felsic: granitic: >65% silica, generally light-
colored
- intermediate: andesitic: 55-65% silica,
generally medium colored (medium
gray)
- mafic: basaltic: 45-55% silica, usually dark
colored
- ultramafic: <45% silica, generally very
dark colored

26. - these are rocks that are formed at or
near the surface of the Earth
- sedimentary processes include:
weathering of rocks, erosion, sediment
transport and deposition (compaction
and cementation)

27. • Temperature and pressure at the Earth’s
surface are low, allowing for the
sedimentary processes to happen
• Sediments: solid fragments of organic
or inorganic materials from weathered
and eroded pre-existing rocks and
living matters

28. - Common sedimentary features:
a.)fossil assemblages: remains and traces of
plants and animals that are preserved in
rocks
b.) stratification or layering (strata which is
>1cm is called bedding and < 1cm is
called lamination):
layering is the result of a change in grain
size and composition; each layer
represents a distinct period of deposition

29. - Common sedimentary features:
a.)fossil assemblages: remains and traces of
plants and animals that are preserved in
rocks
b.) stratification or layering (strata which is
>1cm is called bedding and < 1cm is
called lamination):
layering is the result of a change in grain
size and composition; each layer
represents a distinct period of deposition

30. Photo of the Kapurpurawan Formation located at the coastal town of Burgos, Ilocos
Norte, courtesy of riderako.com. Shows series of sedimentary strata

31. Clastic sedimentary rocks
- grains, matrix and cement are the
components of clastic rocks
- clastic rocks are commonly classified
based on particle size
- clastic rocks with volcanic origin (e.g.
pyroclastics) and may have undergone
some stages in the sedimentary processes
could be classified as sedimentary rock
(e.g. Volcanoclastic rocks).

32. Clastic sedimentary rocks
- the presence of variable grain sizes
(including matrix and cement) is
indicative of sedimentary differentiation
which is actually a function of processes
happening in different sedimentary
environments.

33. 1.) Grains: greater than sand-sized minerals
and/or rock fragments.
2.)Matrix: fine-grained (clay to silt sized)
minerals.
3.)Cement: minerals precipitated from
solution that binds the grains and matrix
together

35. 1.) Grains: greater than sand-sized minerals
and/or rock fragments.
2.)Matrix: fine-grained (clay to silt sized)
minerals.
3.)Cement: minerals precipitated from
solution that binds the grains and matrix
together

36. • Rudaceous Rocks: (rudites) >50% clasts
diameter >2mm made up of primarily
rock fragments
• Arenaceous Rocks: (areAnites) >50%
sediments diameter between 0.063-2mm
can contain high quartz %.
• Argillaceous Rocks: (argillites) >50%
sediments diameter <0.063mm and
made up mainly of clay minerals and
quartz grains to a much lesser extent

37. Non-clastic sedimentary rocks
- evaporation and precipitation from
solution or lithification of organic
matter
- classified as evaporites (halite,
gypsum and dolostone),
precipitates (limestone) and
bioclastics (coal, coquina)

38. Non-clastic sedimentary rocks
• Evaporites: rocks formed from the
evaporation of water leaving the
dissolved minerals to crystallize
• Precipitates: rocks formed when
minerals from a mineral supersaturated
waters start to crystallize at the bottom of
the solution
• B i o c l a s t i c : rock formed from
compacted organic matter

41. - formed below the surface of the
earth through the process of
metamorphism with the
recrystallization of minerals in
rocks due to changes in pressure
and temperature conditions

42. 2 KINDS OF METAMORPHISM:
1.) CONTACT METAMORPHISM
2.) REGIONAL METAMORPHISM

43. 1.) CONTACT METAMORPHISM
- heat and reactive fluids as main
factors: occurs when a pre-existing
rock gets in contact with magma
which is the source of heat and
magmatic fluids where metamorphic
alterations and transformations occur
around the contact / metamorphic
aureole of the intruding magma and
the rock layers.

44. 1.) CONTACT METAMORPHISM
The aureole occurs on different scales
depending on the sizes of the intruding
magma and the amount of water in
the intruded rocks and the reactive
fluids coming from the magma.
- creates non-foliated metamorphic
rocks
- example: hornfels

45. 1.) REGIONAL METAMORPHISM
- pressure as main factor: occurs in
areas that have undergone
considerable amount of
mechanical deformation and
chemical recrystallization during
orogenic event which are
commonly associated with
mountain belts

46. 1.) REGIONAL METAMORPHISM
- occurs in a regional/large scale
- creates foliated metamorphic rocks
- examples: schist, gneiss
- non-foliated rocks like marble also
form through regional
metamorphism, where pressure is
not intense, far from the main
geologic event

47. 1.) REGIONAL METAMORPHISM
- occurs in a regional/large scale
- creates foliated metamorphic rocks
- examples: schist, gneiss
- non-foliated rocks like marble also
form through regional
metamorphism, where pressure is
not intense, far from the main
geologic event

48. • Non-foliated rocks: Hornfels (left), a fine-
grained rock that forms through contact
metamorphism of noncarbonate rocks.
Marble (right), a recrystallized rock that
forms from the metamorphism of limestone
or dolostone
• Foliated rocks: Slate, phyllite, schist and
gneiss from shale as precursor rock. The
stages of transformation are manifestations
of increasing metamorphic grade with
increasing pressure