Lesson 4.2 Flashcards
are formed from
solidification of magma or lava
which flows out from depth.
Igneous rocks
are the components of almost
all types of igneous rocks.
Minerals such as quartz, feldspar,
pyroxene, olivine, amphibole, and
mica
Igneous rocks are
characterized by
intergrowth of crystals and/or
volcanic glass.
Crystal size is _
proportional to the cooling
rate of magma.
directly
are formed
deep underground,
Big crystals
are formed
near the surface.
smaller crystals
forms
when magma or volcanic fragments
erupt and solidify on Earth’s surface
which results in very fine-grained
rock with very small crystals that
could not be seen through naked
eye.
also known as a volcanic rock
extrusive igneous rock
forms when magma
crystallizes within the crust
and is composed of
medium to coarse grains. It
is also known as a plutonic
rock.
intrusive igneous rock
Igneous rocks can be named using the binary system which
is mainly based on its
texture
composition
It is directly proportional to the cooling rate of magma. This means that when the crystals are big, it denotes that the rock is formed deep underground
since the magma has a longer trip to the surface giving it longer time to cool down
at a very slow rate. On the other hand, magma cools quickly (fast cooling) near the
surface that causes formation of smaller crystals since it is given few time to form.
Crystals form when magma are cooled. A general model is created to show the
progression of silicate crystallization at specific temperature. It is called
Bowen’s
reaction series
which is developed by petrologist Norman L. Bowen
2 branchs of bowen’s reaction series
discontinuous branch
continuous branch
discontinuous branch
olivine
pyroxene
amphibole
biotite mica
old people are boring
continuous branch
calcium rich plagioclase feldspar
to sodium rich plagioclase feldspar
3 textures of extrusive igneous rock
smooth
full of holes
wit hlarge crystals embedded in a fine ground mass
examples of extrusive igneous
obsidian
pumice
andesite
two types of intrusive bodies
concordant and discordant
When the pre-existing rock bed is cut across by an intrusive body
concordant
while if it runs parallel to the bedrock, igneous rock bodies are called
discordant
sills
concordant
dikes and laccolith
discordant
are large intrusive bodies formed deep within Earth
Batholiths
textures of igneous rocks
aphaneitic
phaneritic
pegmatitic
vesicular
porphyritic
amygdaloidal
pyroclastic
has crystals that are too fine-grained to be seen by the naked
eye or even with the help of a hand lens
Aphanitic
has grains that are coarse enough to be visible to the eye
Phaneritic
has crystals are greater than 3 cm due to very slow cooling
Pegmatitic
contains tiny holes called vesicles due to gas bubbles in the
lava or magma
Vesicular
are rocks where larger crystals are embedded in smaller crystals
Porphyritic
is when vesicles are filled by low-temperature minerals after
the solidification of magma
Amygdaloidal
is formed from the consolidation of individual rock fragments
that are ejected during a volcanic eruption.
Pyroclastic
igneous rock is usually light colored and contains large amounts of
quartz, potassium feldspar, and plagioclase.
is also called granitic igneous
rock
Felsic
igneous rock is medium gray or medium green and consists
of major minerals like amphibole, plagioclase, and feldspar
Intermediate
igneous rock is dark gray to black-colored and composed largely of
plagioclase and amphibole with small amounts of olivine.
is also called as
basaltic igneous rock.
Mafic
igneous rock has a very dark green to black shade and consists
largely of olivine and pyroxene.
Ultramafic
Types of Igneous Rocks Based on Mineral Composition
Felsic
Intermediate
Mafic
Ultramafic
