GEOL210 Midterm

Geology

is the scientific study of the solid Earth including the materials that makeup the planet and the processes that shape the planet

Physical Geology

examines the materials (minerals, rocks, air and water) composing the earth and the processes that operate both beneath and on the surface (mountain building, volcanic eruptions, earthquakes).

Historical geology

aims to understand the origin of earth and its development through time (the study of rock strata, fossils, and geologic events utilizing the geologic time scale)

Environmental geology

studies the interaction between humans and the geological environment

Urban Geology

(New emerging science) that studies the diversity of Earth science linkages within the urban environment including urban population concentration

Steady State Theory

They said that matter is continuously created at a rate that keeps the average density of the Universe the same as it expands.
Universe has always existed, no beginning and no end, eternal existence
Matter alone exists for an infinity of time

The Big Bang theory

Lemaitre (1931) declared that the universe had a beginning and that it was expanding as a result of something that had triggered it.
Had 2 main theories:
The ball was full of quarks
Inside there was nothing and non-dimensional. It was only energy. Energy can create matter. e=mc2
A single point of concentrated energy exploded -assumes that all parts of the universe began expanding simultaneously.

Universe as raisin bread

Bread expands and raisins have moved away from each other like galaxies in the expanding universe.

String Theory

recent contender for the big bang theory
the big bang may not have been the origin of the universe but simply a violent transition from acceleration to deceleration. Pre-Bang universe.

What did the heat from big bang cause?

- The immense heat of the explosion caused: Fusion of quarks (fundamental particles) Formed protons (1H) and neutrons
hydrogen (proton) begun to populate the universe

Nucleosynthesis

Happened after the big bang before stars formed
Collision and fusion of hydrogen atoms

Big Bang nucleosynthesis

First stars initiated nuclear fusion ~1 billion years after the Big Bang a-Fusion of 2H to 4He

Stellar nucleosynthesis (Red Giant Phase)

Friction between particles increased Increased heat allowed for the fusion of helium into carbon
b-4He + 4He → 8Be + 4He → 12C
-Small amount of 16O is also produced by adding 4He to 12C

How was the periodic table arranged?

After big bang, H started to bond together to form different elements. It worked its way down the periodic table. starting from lightest elements moving to heaviest.
New phase of star collapse sees C-12C + 12C → 24Mg → 20Ne + 4He D-16O + 16O → 32S → 28Si + 4He Production of 'even-numbered' elements up to iron (Fe)

cosmic dust

very fine particles of solid matter found in any part of the universe.
iron, minerals, rocks, gas, Ices

Dense vs light elements

Dense elements sank to the center of the Earth ( core of nickel and iron.)
Light elements floated to the surface. (Crust of aluminum, oxygen and silicon)

How long ago was the earth formed?

4.6 billion years ago

Layers of the Earth

crust (0-36km), upper mantle (35-60) , mantle (35- 2890), outer core(2890-5150), inner core (5150-6360)

What is in the crust

The crust floats on top of the mantle. It is composed of basalt rich oceanic crust and granitic rich continental crust.

Earths meteors

The Earth has about 100 craters more than 0.1 km in diameter; erosion has made most of them hard to discern. One of the largest is in Canada, in Northern Quebec (Manicouagan).
Most meteorites are rocky ; some are iron.

tectonic plates

At the beginning of the 20th century, a controversial hypothesis was proposed by Alfred Wegener. He proposed that continents were not fixed masses of land on the earth's surface, but rather moving continents on a Molten earth's interior.
His reasoning was actually quite simple at first the continents of South America and Africa fit together like a puzzle

tectonic plates (fossil evidence)

Similar or identical fossils are found on both sides of the Atlantic

tectonic plates Structure Evidence

Mountain ranges on either side of the Atlantic are the same - which brings us to the conclusion that the land masses were once together as one.

What drives plate tectonics?

mantle convection
Hot, less dense material rises, cool denser material sinks
Slow process
Drives motion of tectonic plates (lithosphere)
Very slow process. The mantle when subjected to heat and pressure in the Earth's interior over millions of years can melt and flow . -Cold, denser material convects downward and hotter, lighter material rises because of gravity

ex: The Red Sea represents a young rift which is just beginning to separate Arabia from Africa.

divergent tectonic plates

A tectonic boundary is where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates. It can also result in trenches and river formation.

divergent tectonic plates examples

ex: The Red Sea represents a young rift which is just beginning to separate Arabia from Africa.
The middle of the Atlantic Ocean is a divergent margin which is being torn, or rifted, apart...the two plates are separating continuously at a rate of several cm/yr

convergent tectonic plates

Plates that move towards each other
Instead of two plates being created, they are being: (a) consumed or (b) colliding

convergent tectonic plates example

The Juan de Fuca plate dives beneath North America. This subduction zone is known for producing earthquakes of great magnitudes

tectonic plates transform margin

Here, plates are neither created nor destroyed... ...they simply slide by one another

tectonic plates transform margin example

Transform plate boundary responsible for The San Andreas in California

does a rock need only one mineral?

No, A rock is composed of one or more minerals

Why study minerals?

Minerals are the building blocks of our planet
-Minerals make up the rocks that make the earth
landscapes
-Industrial minerals=serve as raw materials for
manufacturing chemicals
-Ore minerals=valuable minerals (gold, copper), and
energy resources like uranium
-Gems=minerals used for jewelry

What is a mineral

an element found naturally in rocks and soils

What 5 things must a mineral do to be a mineral?

1. Occur naturally
2. Be a solid ( no free atoms)
3. be crystalline ( atoms are organized)
4. be of definite chemical composition
5. be formed by inorganic processes

All minerals must be solid...

Minerals are the building blocks of our planet
-Minerals make up the rocks that make the earth
landscapes
-Industrial minerals=serve as raw materials for
manufacturing chemicals
-Ore minerals=valuable minerals (gold, copper), and
energy resources like uranium
-Gems=minerals used for jewelry

all minerals must be crystalline

a crystalline solid is a material with an internal atomic structure that is organized in a regular, repeating structure.
Eg. Halite, NaCl (table salt)
Cubic arrangement of Na+
(red) and Cl-
(yellow) ions
Halite crystals are cubic in shape.

amorphous

A non crystalline solid is termed amorphous solid such as glass and
plastic

glass vs. quartz

All minerals are inorganic.

This means that they do not come from living things.
➢Organic substances are plants and animals or the things that are left
behind when they die.
➢Sometimes those dead plants and animals are turned into a mineral
by heat and pressure, such as coal.
The key here is that the minerals are the result of
Geological Activities and not directly the product of
biological organisms such as bones, shells, pearls,
ivory, etc.

all chemicals have a definite composition

this means that there is a specific chemical formula for each mineral.
ex: quartz is always made up of one silicon atom bonded with two oxygen
ex: pyrite is always one atom of iron to two atoms of sulfur.

Can two minerals have the same chemical composition?

Two different minerals can have the same chemical
composition but different properties and different structures
Diamond and graphite share the same chemical composition:
they are polymorphs of the element Carbon (C)

what are the physical properties of a mineral?

Crystal form
Luster
Colour
Streak
Hardness
Cleavage
Fracture
Specific Gravity

define Crystal form

is the external reflection of the internal mineral arraignment

what are the largest minerals in the world?

World’s largest crystals:
the mineral gypsum (CaSO4
.2H2O)
Precipitation from water solutions
in mexico

3 main cristal forms

amorphous is without shape

define crystal habits

The term crystal habit describes the favored growth pattern of the crystals of a
mineral species. (supplement to the system, descriptive)

Law of constancy of interfacial angles
Or
First Law of crystallography

The angles between corresponding
faces on different crystals of one
chemical composition have a constant
value.

crystal colour

Visible hue of a mineral
Usually, we notice the color of a mineral first. Some
minerals are easily identified by color because they are
never any other color.
For example, Malachite is always green. Azurite is
always blue.

why isn't colour a reliable source of identifying?

Chemical impurities can change the colour of a
mineral without changing its basic make-up
ex: quartz comes in many different colours.

mineral streak

When a mineral is rubbed firmly across an unglazed tile of
white porcelain (a streak plate), it leaves a line of powder.
This is called the streak. The color of the streak is always the
same, whether or not the mineral has impurities.
For example, quartz leaves a white streak, whether it’s
purple (amethyst), pink (rose quartz), or brown (smoky
quartz).

hardness

Scratch-resistance
The hardness is the resistance of a mineral to scratching

what is hardness measured on?

Mohs hardness scale

mineral cleavage

When a mineral sample is broken with a hammer, it breaks along
planes of weakness that are part of its crystalline structure. These
breaks are cleavages.
Some minerals break only in one direction. Others break in two or
more directions.

Mineral fracture

Breakage not along
planar surfaces
2 main types:
conchoidal or irregular

non metallic lusters

Vitreous (glassy) -- example: quartz, tourmaline
Resinous (like resin from a tree) -- example: sphalerite
Greasy or waxy -- example: turquoise
Pearly -- example: talc
Silky -- example: asbestos
Dull or earthy -- example: bauxite

mineral luster

Luster is the way the surface of a mineral reflects light.
Two general types of luster -- metallic and non-metallic.

specific gravity

the density of a substance relative to the density of water

mineral transparency

Transparency describes how well light passes through a
mineral sample.
There are three degrees of transparency:
transparent, translucent, and opaque.
-You can see objects through a transparent mineral.
-You can see light, but no objects through a translucent
mineral.
-You can't see anything through an opaque mineral.

mineral twinning

• If a crystal is subjected to stress during growth
or temperature/pressure conditions different from those
under which it originally formed, two or more intergrown
crystals are formed in a symmetrical fashion.
These symmetrical intergrowths of crystals are called
twinned crystals.

How many minerals are there?

Roughly 4200
Fifty or so are added each
year

How do minerals form

Crystallize…
• from liquids (molten rock, aqueous
fluids..)
• during solid-state recrystalliation
inside solid rocks (metamorphism)
• from gases (volcanic gases, trapped
gases in open spaces in rocks)
Or are created from…
• the destruction of earlier minerals
during chemical weathering
– clay minerals and oxides are most
common
– think “mud” and “rust”

what are the common elements of minerals

Nearly 97% of the atoms in Earth’s crust are represented
by the 8 most common elements (~50 wt% = oxygen!)
• O, Si, Al, Fe, Ca, Na, K, Mg

Grouped according to
common anionic
groups
• Si + O make up the
most important
anionic group

what is the basic building block of the silicates

The basic building block of the silicates is the
[SiO4]^4-
tetrahedron, represented in a “ball-andstick” model and as a filled polyhedron

homogeneous crystalline structure

A homogeneous crystalline structure in which one or more types
of atoms or molecules may be partly substituted for the original
atoms and molecules without changing the structure
(Temperature dependant).

olivine group

has 2 sides: magnesium and iron. On the 100% magnesium side we have Forsterite (Mg2SiO4). On the 100% iron side we have Fayalite (Fe2SiO4).

Plagioclase group

has 2 sides: calcium and sodium. On the 100% calcium side is Anorthite (CaAl2Si2O8
). On the 100% sodium side is Albite(NaAlSi3O8
).

Cristallography

uses electromagnetic radiation (specifically, X-rays) to determine the molecular and atomic structure of a crystal.

Ionic Bonding

Such a bond forms when the valence (outermost) electrons of one
atom are transferred permanently to another atom.

diamond vs. graphite bonding

diamond has covalent bonding while graphite has ionic bonding

covelent vs. vander walls with sheets

covelant bonds will be within the sheets while walls bonding will be between the layers of sheets.

Nesosilicate

Independant tetrahedra share no
oxygen atoms, held by positive ions
ex: Olivine (Fe,Mg)2SiO4

2a-Inosilicate (Single Chain)

Two single chains of tetrahedra held by
positive ions

2b-Inosilicate (Double Chain)

Two single chains of
tetrahedra link by sharing
oxygen

3-Sheet Silicate

Each tethadera shares 3 oxygens

4-Framework Silicate

Each tetrahedra shares all
four oxygens with its
neighbors

bowens reaction series

A general model for explaining how magmatic rocks form and the order of
appearance of the common silicate minerals from a magma.
-Shows minerals crystallising as temperature decreases
-Composition of magma changes as the system evolves

Igneous Rocks

Formed by consolidation and cooling of magma. If the rock
cools below the ground it is called a plutonic rock and if the
rock cools above the ground it is called a volcanic rock.
igneous meaning fire.
originate from the evolution of this magma
Either under or above the crust.

Sedimentary Rocks

Rocks at the surface which react with
water, ice and air. These interactions cause them to break
down into smaller particles, called weathering. These
particles are transported by wind, water or ice and once
deposited are called sediment.

Metamorphic rock

meta meaning change, morphe meaning form
change.
These rocks have been changed as a result of high temperature,
high pressure, or both. Metamorphism the process that forms
metamorphic rocks from sedimentary or igneous rocks is similar to
what happens when a potter fires clay in an oven. The mineral
grains undergo a series of chemical reactions and a new compound
forms.

Crust rocks

Crust – 95% igneous or metamorphic derived from igneous,
5% sedimentary

Surface rocks

Surface – 75% sedimentary, 25% igneous

magma

The term used to describe the liquid when it is
within the Earth's crust or mantle.

lava

The term used to describe the liquid when it has
reached the surface of the Earth.

Molten rock composed of:

A liquid portion, called melt, that is composed of mobile ions of O,
Ca, Na, K, Si, Al, Mg, Fe
Solids, if any, are silicate minerals that have already crystallized
from the melt, and/or residual minerals
Volatiles, which are gases dissolved in the melt, including water
vapor (H2O), carbon dioxide (CO2),

Partial Melting

Incomplete melting of a 'parent rock' to produce a molten rock (like
magma) with a different chemical composition (Primary magma).
This happens because different minerals melt at different
temperatures.

What three conditions can lead to the formation of magma?

1-Melting as a result of a decrease in pressure (decompression)
2-Melting as a result of the addition of volatiles
3-Melting as a result of heat transfer from rising magma

Melting at a Subduction Zone

Below 150 km, heat causes
volatiles within the
downgoing plate to be
released into the
asthenosphere (ultamafic
rock) of the overriding plate.
Partial melting of the
asthenosphere produces
basaltic magma, which
migrates upward through the
lithosphere to erupt at the
surface.
Magma in any case rises because it is less dense than the
surrounding rock and thus is buoyant.

Hydration Melting-subduction zones

Adding water to a dry solidus will decrease
the temperature of melting a basalt.
Water percolates into a solid hot rock and triggers the melting.

Melting and heat transfer

Melting as a result of heat transfer can occur when a hot
magma rises into rock that has a lower melting
temperature.
Exp: Hot basaltic magma rising from the mantle can make
the surrounding intermediate composition crust to melt.

MAGMA EVOLUTION

A change in the composition of a magma
body is known as magma evolution
Magma evolution can occur by fractional
crystallization, assimilation, or magma mixing

Fractional crystallization

involves the changing of magma composition by the removal of denser early-formed ferromagnesian minerals by crystal settling Note that the separation of early-formed ferromagnesian minerals from a magma body increases the silica content of the remaining magma and leaves behind a more mafic residue

Assimilation

occurs when a hot magma melts and incorporates more felsic surrounding country rock

Magma mixing

involves the mixing of more and less mafic magma to produce one of intermediate composition

make sure to watch video

Partial Melting and Crystallization are very important in
understanding igenous rocks and thus the evolution of the
mantle and the continental crust

Intrusive igneous rocks

form when magma solidifies underground
•Layman’s term = granitic
•Granite is most common type

Extrusive igneous rocks

form when magma solidifies at the Earth’s surface (lava)
•Layman’s term = basaltic
•Basalt is most common type
ex: andesite and basalt

what is a pluton?

Many of the structures that result from the emplacement of igneous material are
called plutons.
Mount Royal is a Pluton.
Small plutons (exposed over <100 km2) are called stocks
Large plutons (exposed over >100 km2) are called batholiths

Dikes and sills

Dikes are created when magma is injected into fractures. Sills are created when magma is injected in
between sedimentary layers for example.

What are the four types of magma based on silica?

Four types of magma based on silica (SiO2) abundance:
Ultramafic <45 wt%
Mafic (basic) 45-51 wt%
Intermediate 52-65 wt%
Felsic (silicic) 66-75 wt%