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Geology
The rock cycle – Earth materials and their stories
Experiments in the lab and working with rock kits
(in school)
Plate Tectonics – The Dynamic Earth
The story of fossils
The Geological History of the Arava Valley, and
its margins
The Geology of the Arava in the view of the Rock
Cycle
Geology and man in the Arava Valley
‫ד"ר חנן גינת‬
‫ד"ר ירון פינצי‬
The rock cycle
In the view of EARTH MATERIALS
The rock cycle in the view of the rock groups
Some definitions:
Minerals - The building blocks of rocks. Rocks are made of
minerals; the minerals can be colored and made of different
ingredients
Rock - A naturally occurring aggregate of
minerals
or: Any mass of mineral matter which forms part
of the Earth’s crust. Rock may consist of only
one mineral species (mono-mineral rock) or be
an aggregate of mineral species.
Rock Cycle - A cycle that shows how rocks are formed and the
processes in the earth crust and above.
atom
particles
atoms
molecules
Minerals
rocks
Earth Materials “Hierarchy”
For rocks
identification we
use:
- color
- hardness
- fizz with acid?
- malleability
- structure
- special
characteristics
Igneous Materials
(rocks and minerals)
Igneous Processes
Igneous structures
and phenomena
Some interesting questions:
Write five questions about magmatic rocks
and processes
Some interesting questions:
1.Why are there so many different kinds
of igneous rocks?
2. What is a magma chamber?
3. What is “a cold environment”
and “a hot environment”?
4. What is the difference between eruption and expulsion?
5. What is the engine that gives the power to the volcanic processes.
6. What is the right place of the igneous rocks in the rock cycle?
7. Are there really 70,000 km. of volcanic
mountain in the deep oceans?
(Igneous = magmatic)
Contents
1. The igneous rocks – characteristic and the story
behind them.
2. Simple experiment to demonstrate volcanic
processes.
3. Identification of magmatic phenomena and their
evolution
4. Virtual field trip in volcano environment (and
mountains)
The red rocks
rhyolite
granite
rhyolite porphir
The gray rocks
(the intermediate rocks)
andesite
diorite
Porphiritic
andesit
pumice
The black rocks
gabbro
basalt
obsidian
Color/
Crystal size
Fine grained
(volcanic)
Coarse
grained
(plutonic)
porphir
red
gray
black
The main reasons for the high variety of the igneous
rocks are:
1. The crystal size
Salol that
crystallize
above cold
glass
Observations:
- small crystals
- fast crystallization
Conclusions:
Volcanic rocks
Salol that
crystallize
above hot
glass
Observations:
- big crystals
- slow crystallization
Plutonic rocks
1. Igneous rocks with coarse crystals crystallize slowly in a “hot environment”
2. Igneous rocks with fine crystals crystallize fast in a “cold environment”
Demonstration of magmatic processes
The water
The Surface
The sand
The environment
rock
The heater
The heating origin
What are these hot and cold environments?
1. Is it in different latitude (for example in Antarctica and Sahara Desert)?
2. Is it under the sea and above continent?
3. Or….????
Climate map
2. The origin of the magma and its composition
3. Different magmatic processes (definitions and pictures)
explosion
eruption
A. A blowing
apart with force
B. The act
or process
of moving
out
intrusion
C. The act or
process of pushing
under the surface
Injection
D. A liquid
passed
through a
needle or
small
opening
Geological quiz
Find the right name of the
phenomena and the
necessary conditions that
permit it.
Columnar Basalt
- Magma fast cooling
- Weathering processes along the cracks
Ropy basalt
- Very rubble lava
Dykes
- Joints in the deep crust
- vertical or horizontal injection of magma
- weathering and exposure of the dykes
Travertine – white
sediments of hot water
- Presence of groundwater
- Presence of heat (as hot magma)
- Presence of joints, that the hot
water can come through
Mt. Etna, Sicilia , Italy
http://www.sicilian.net/etna2002/
Stages of the
development
of a volcano
You have to
sort them to
the right stages
and to write the
what happened
in each stage
Mount St. Helen, USA
15.5.1980
http://vulcan.wr.usgs.gov/Volcanoes/MSH/
6.10.2004
New Zealand volcano
Some more pictures and figures
‫להמשך המצגת‬
‫המשך‬
Why are there so many kinds of
magmatic rocks?
The global aspects
The Earth Dynamic map – mountains, subduction
areas and the ocean ridges
Rings of fire
Volcanism along the east part of Ethiopia
The Blue Nile
Afar
Valley
‫בזלות צעירות מאוד – עדויות לזרימה‬
‫מלכודות אוויר וסדקים בבזלות הצעירות‬
Metamorphic rocks and processes
New rock textures and new mineral assemblages
develop when rocks are subjected to elevated
temperatures and pressures. Changes that take place
while the rock is still solid are called metamorphism.
Metamorphic changes start at about 150oC (equivalent to a depth within
the Earth of 5 km) and cease around 800oC where the rocks start to melt.
The Pietà, Michaelangelo's most famous
statue, was carved from marble, a
metamorphic rock from the Carrara quarries in
Italy.
What are the three types of metamorphism?
The processes that cause changes in texture and in mineral
assemblage in metamorphic rocks are mechanical deformation and
chemical recrystalization.
The origin rocks
Granite
Limestone
Metamorphosed rocks
Gneiss
Marble
Schist
Clay
Sandstone
Quartzite
And Some times with new
metamorphic minerals
Schist Garnet
Tourmaline Mica Schist
Pore fluids allow dissolved
minerals to be transported and reprecipitated elsewhere; they also
speed up chemical reactions.
FoliationThe schist
The composition of metamorphic rock is strongly controlled
by the composition of the parent rock, but other factors also
apply.
The growth of new mineral phases during
metamorphism is primarily controlled by
temperature. High temperatures, pressures
and abundant pore fluids result in
metamorphic rocks with large mineral grains
The original structure
Elongated structure after metamorphism
The changes that occur during metamorphism often produce a
texture called foliation. This is caused by the preferential orientation
of newly-formed micaceous minerals
Foliation in low-grade
metamorphic rocks is called
slaty cleavage. Both foliation
and cleavage develop
perpendicular to the direction of
maximum stress
The diagram shows the conditions of pressure and temperature
in which diagenesis, metamorphism, and melting occur in the
Earth's crust.
Metamorphic changes start at about 150oC (equivalent to a depth within the Earth
of 5 km) and cease around 800oC where the rocks start to melt
How do solid rocks change?
As temperature and stress increase on a sedimentary rock, like shale,
different mineral assemblages are formed, ultimately resulting in the
metamorphic rocks slate, phyllite, schist, and gneiss.
What are the metamorphic facies?
For a given rock composition, the assemblages of minerals that are formed
under a specific temperature and pressure are always the same. This fact
allows us to define specific metamorphic facies.
Sedimentary rocks that are saturated with water and subjected to
elevated temperatures and pressures undergo burial metamorphism.
Regional metamorphism
occurs under differential
stress and elevated
temperatures as a result
of the collision of
tectonic plates.
Regionally
metamorphosed rocks
commonly extend over
areas of thousands of
square kilometers
Subduction Zone
Paired metamorphic facies are common in subduction zone tectonic
environments. Ocean floor basalts exposed to variable pressures
and temperatures form well-foliated greenschists and amphibolites,
or weakly-foliated blueschists and eclogites.
The rock cycle
In the view of EARTH MATERIALS
The diagram shows the conditions of pressure and temperature in which
diagenesis, metamorphism, and melting occur in the Earth's crust.
Metamorphism
New rock textures and new mineral
assemblages develop when rocks are
subjected to elevated temperatures and
pressures. Changes that take place while
the rock is still solid are called
metamorphism
The rock
cycle through
the view of
internal and
external
PROCESSES