Magmatism

Earth and Life Science
Quarter 1 – Module 7:
Magmatism

After going through this module, you are
expected to:

1. describe the characteristics of magma;
2. identify the substances/elements present
in magma; and
3. explain the processes involved in the
formation of magma.

Taal volcano located at
the province of
Batangas

How magma got inside the

volcano?

●composed of
semi-liquid hot molten
rocks

●located beneath the
Earth,

●specifically in the
melted mantle rock
and oceanic plate.

What is Magma?

lava?

magma?

Magmatism is a process
under the earth’s crust
where formation and
movement of
magma occur.

How is magma
formed?

The magma
present in the lower
crust and upper
mantle of the Earth
is formed or
generated through
the process of
partial melting.

This is a diagram showing how minerals in rocks
undergo partial melting.

This solid rock
contains the
minerals quartz,
feldspar, biotite, and
hornblende.

The first minerals
that melt are quartz
and some types of
feldspar. The
background
represents magma.

Minerals such as
biotite and
hornblende
generally melt last,
which changes the
composition of
magma.

1. AN INCREASE IN
TEMPERATURE:

Conduction in mantle happens when
heat is
transferred from hotter molten rocks
to the Earth’s cold crust.

This process is known as heat
transfer.

As magma rises, it is often hot
enough to melt the rock it
touches. It happens at convergent
boundaries, where tectonic plates are
crashing
together.

2. A DECREASE OF PRESSURE: Mantle rocks remain solid when exposed to high
pressure. However, during convection, these rocks tend to go upward (shallower
level) and the pressure is reduced. This triggers the melting of magma. This is
known as decompression melting. This process occurs at the Mid-Ocean Ridge,
an underwater mountain system.

3. ADDITION OF VOLATILES: When water
or carbon dioxide is added to hot rocks,
flux melting occurs.

The melting points of minerals within the
rocks decrease.

It occurs around subduction zones.

Concept Map
Directions. Complete the concept map about Magmatism.
Choose your answers on
the box below.