Geology and Nonrenewable Minerals

1
Geology and Nonrenewable Minerals

• Chapter 12

2
What are the earths major geological processes
and hazards?

• Section 12-1

3
The earth is a dynamic planet

• Geology is the science devoted to the study of
  dynamic processes occurring on the earths
  surface and in its interior.
• Three major concentric zones.
• The core is the earths innermost zoneextremely
  hot, with a solid inner part encircled by a
  liquid core of molten or semisolid material.
• Surrounding the core is a thick zone called the
  mantlesolid rock, but under its rigid outermost
  part is the asthenosphere, a zone of hot, partly
  melted rock that flows.

4
The earth is a dynamic planet

• The outermost and thinnest zone of the earth is
  the crust.
• Continental crust, which underlies the
  continents.
• Oceanic crust, which underlies the ocean basins
  and makes up 71 of the earths crust.
• The combination of the crust and the rigid
  outermost part of the mantle (above the
  asthenosphere) is called the lithosphere.

5
Major features of the earths crust and upper
mantle
6
Folded mountain belt
Volcanoes
Abyssal plain
Abyssal floor
Oceanic ridge
Abyssal floor
Abyssal hills
Craton
Trench
Oceanic crust (lithosphere)
Continental shelf
Abyssal plain
Continental slope
Continental rise
Continental crust (lithosphere)
Mantle (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
Fig. 12-2, p. 277
7
The earth beneath your feet is moving

• Convection cells or currents move large volumes
  of rock and heat in loops within the mantle like
  gigantic conveyer belts.
• Flows of energy and heated material in these
  convection cells caused the lithosphere to break
  up into a dozen or so huge rigid plates, called
  tectonic plates.
• Continents have split apart and joined as
  tectonic plates drifted atop the earths
  asthenosphere.

8
The earth beneath your feet is moving

• The forces produced at these plate boundaries can
  cause earthquakes, erupting volcanoes and
  mountains to form.
• Oceanic plates move apart from one another
  allowing magma, to flow up between them.
• Much of the geologic activity at earths surface
  takes place at the boundaries between tectonic
  plates as they move in the resulting cracks.
• Oceanic ridges may have peaks higher and canyons
  deeper than those found on the earths continents.

9
The earth beneath your feet is moving

• When two oceanic plates collide, a trench
  ordinarily forms at the boundary between the two
  plates.
• When an oceanic plate collides with a continental
  plate, the continental plate usually rides up
  over the denser oceanic plate and pushes it down
  into the mantle in a process called subduction.
• The area where this collision and subduction
  takes place is called a subduction zone.
• Tectonic plates can also slide and grind past one
  another along a fracture (fault) in the
  lithospherea type of boundary called a transform
  fault.

10
The earths crust is made up of a mosaic of huge
rigid plates
11
Spreading center
Ocean trench
Oceanic tectonic plate
Oceanic tectonic plate
Oceanic tectonic plate
Plate movement
Plate movement
Oceanic crust
Tectonic plate
Subduction zone
Oceanic crust
Continental crust
Continental crust
Cold dense material falls back through mantle
Material cools as it reaches the outer mantle
Hot material rising through the mantle
Mantle convection cell
Mantle
Two plates move towards each other. One is
subducted back into the mantle on a falling
convection current.
Hot outer core
Inner core
Fig. 12-3, p. 277
12
The earths major tectonic plates
13
EURASIAN PLATE
NORTH AMERICAN PLATE
ANATOLIAN PLATE
CHINA SUBPLATE
JUAN DE FUCA PLATE
CARIBBEAN PLATE
PHILIPPINE PLATE
ARABIAN PLATE
AFRICAN PLATE
INDIA PLATE
PACIFIC PLATE
PACIFIC PLATE
COCOS PLATE
SOUTH AMERICAN PLATE
NAZCA PLATE
AUSTRALIAN PLATE
SCOTIA PLATE
ANTARCTIC PLATE
Transform faults
Divergent plate boundaries
Convergent plate boundaries
Fig. 12-4, p. 278
14
The San Andreas Fault
15
Internal pressure in a volcano can cause lava,
ash, and gases to be ejected
16
Extinct volcanoes
Eruption cloud
Ash Acid rain
Ash flow
Lava flow
Mud flow
Central vent
Landslide
Magma conduit
Solid lithosphere
Magma reservoir
Partially molten asthenosphere
Upwelling magma
Fig. 12-6b, p. 279
17
Earthquakes are geological rock-and-roll events

• Forces inside the earths mantle and near its
  surface push, deform, and stress rocks.
• The stress can cause the rocks to suddenly shift
  or break and produce a transform fault, or
  fracture in the earths crust.
• When a fault forms or when there is abrupt
  movement on an existing fault, energy that has
  accumulated over time is released in the form of
  vibrations, called seismic waves, causing an
  earthquake.

18
An earthquake has certain major features and
effects
19
Liquefaction of recent sediments causes buildings
to sink
Two adjoining plates move laterally along the
fault line
Earth movements cause flooding in low-lying areas
Landslides may occur on hilly ground
Shock waves
Focus
Epicenter
Fig. 12-7, p. 280
20
Earthquakes are geological rock-and-roll events

• The severity of an earthquake is measured by the
  magnitude of its seismic waves.
• The magnitude is a measure of shaking caused by
  the earthquake, as indicated by the size of the
  seismic waves when they reach a seismograph.
• Scientists use the Richter scale, on which each
  unit has amplitude 10 times greater than the next
  smaller unit.

21
Earthquakes are geological rock-and-roll events

• Insignificant (less than 4.0 on the Richter
  scale).
• Minor (4.04.9).
• Damaging (5.05.9).
• Destructive (6.06.9).
• Major (7.07.9).
• Great (over 8.0).

22
Earthquakes on the ocean floor can cause huge
waves called tsunamis

• A tsunami is a series of large waves generated
  when part of the ocean floor suddenly rises or
  drops.
• Most large tsunamis are caused when certain types
  of faults in the ocean floor move up or down as a
  result of a large underwater earthquake, a
  landslide caused by such an earthquake, or in
  some cases by a volcanic eruption.
• Tsunamis are often called tidal waves, although
  they have nothing to do with tides.

23
How a tsunami forms
24
As the waves near land they slow to about 45
kilometers per hour but are squeezed upwards and
increased in height.
Waves move rapidly in deep ocean reaching speeds
of up to 890 kilometers per hour.
Waves head inland causing damage in their path.
Earthquake in seafloor swiftly pushes water
upwards, and starts a series of waves.
Undersea thrust fault
Upward wave
Bangladesh
India
Myanmar
Thailand
Malaysia
Sri Lanka
Earthquake
Sumatra
Indonesia
December 26, 2004, tsunami
Fig. 12-8, p. 281
25
Earthquakes on the ocean floor can cause huge
waves called tsunamis

• They can travel far across the ocean at the speed
  of a jet plane.
• In deep water the waves are very far
  apartsometimes hundreds of kilometersand their
  crests are not very high.
• As a tsunami approaches a coast, it slows down,
  its wave crests squeeze closer together, and
  their heights grow rapidly.
• Hits a coast as a series of towering walls of
  water that can level buildings.

26
Banda Aceh before and after the tsunami of
December 2004
27
How are the earths rocks recycled?

• Section 12-2

28
There are three major types of rocks

• A mineral is an element or inorganic compound
  that occurs naturally in the earths crust as a
  solid with a regular internal crystalline
  structure.
• A few minerals consist of a single element such
  as gold, silver, and diamond (carbon).
• Most of the more than 2,000 identified minerals
  occur as inorganic compounds formed by various
  combinations of elements, such as salt (sodium
  chloride or NaCl) and quartzite (silicon dioxide
  or SiO2).

29
There are three major types of rocks

• Rock is a solid combination of one or more
  minerals found in the earths crust.
• Some kinds of rock, such as limestone and
  quartzite, contain only one mineral while most
  consist of two or more minerals, such as
  granitea mixture of mica, feldspar, and quartz
  crystals.
• Three broad classes
• Sedimentary rock (e.g. sandstone, limestone).
• Igneous rock (e.g. granite).
• Metamorphic rock (e.g. slate, marble).

30
Simplified rock cycle
31
Erosion
Transportation
Weathering
Deposition
Igneous rock Granite, pumice, basalt
Sedimentary rock Sandstone, limestone
Heat, pressure
Cooling
Heat, pressure, stress
Magma (molten rock)
Melting
Metamorphic rock Slate, marble, gneiss, quartzite
Fig. 12-10, p. 283
32
What are mineral resources and what are the
environmental effects of using them?

• Section 12-3

33
We use a variety of nonrenewable mineral resources

• A mineral resource is a concentration of
  naturally occurring material from the earths
  crust that can be extracted and processed into
  useful products and raw materials at an
  affordable cost.
• Found and extracted more than 100 minerals from
  the earths crust.
• Examples are fossil fuels (such as coal),
  metallic minerals (such as aluminum and gold),
  and nonmetallic minerals (such as sand and
  limestone).
• Minerals are classified as nonrenewable resources.

34
We use a variety of nonrenewable mineral resources

• An ore is rock that contains a large enough
  concentration of a particular mineraloften a
  metalto make it profitable for mining and
  processing.
• High-grade ore contains a large concentration of
  the desired mineral.
• Low-grade ore has a smaller concentration.
• Aluminum (Al) is used for packaging and beverage
  cans and as a structural material in motor
  vehicles, aircraft, and buildings.

35
We use a variety of nonrenewable mineral resources

• Steel, an essential material used in buildings
  and motor vehicles, is a mixture (alloy) of iron
  (Fe) and other elements that are added to give it
  certain properties.
• Copper (Cu), a good conductor of electricity, is
  used for electrical and communications wiring.
• Gold (Au) is used in electrical equipment, tooth
  fillings, jewelry, coins, and some medical
  implants.

36
Each metal resource that we use has a life cycle
37
Stepped Art
Fig. 12-11, p. 285
38
There are several ways to remove mineral deposits

• Shallow mineral deposits are removed by surface
  mining by
• Removing vegetation.
• Removing the overburden or soil and rock
  overlying a useful mineral deposit.
• Placing waste material set aside in piles, called
  spoils.
• Open-pit mining.

39
Harmful effects of extraction, processing, and
use of nonrenewable mineral or energy resources
40
Types of miningOpen pit, strip, contour strip,
and mountaintop removable
41
Undisturbed land
Overburden
Highwall
Coal seam
Overburden
Pit
Bench
Coal seam
Spoil banks
Fig. 12-15, p. 287
42
How long will supplies of nonrenewable mineral
resources last?

• Section 12-4

43
Mineral resources are distributed unevenly

• The earths crust contains fairly abundant
  deposits of iron and aluminum.
• Manganese, chromium, cobalt, and platinum are
  relatively scarce.
• The earths geologic processes have not
  distributed deposits of nonrenewable mineral
  resources evenly among countries.

44
How can we use mineral resources more sustainably?

• Section 12-5

45
We can use nonrenewable mineral resources more
sustainably
46
Three big ideas

• Dynamic forces that move matter within the earth
  and on its surface recycle the earths rocks,
  form deposits of mineral resources, and cause
  volcanic eruptions, earthquakes, and tsunamis.
• The available supply of a mineral resource
  depends on how much of it is in the earths
  crust, how fast we use it, the mining technology
  used to obtain it, its market prices, and the
  harmful environmental effects of removing and
  using it.
• We can use mineral resources more sustainably by
  trying to find substitutes for scarce resources,
  reducing resource waste, and reusing and
  recycling nonrenewable minerals.

47
End of Short Version

• The slides that follow are those taken out of the
  long version of this same lecture. You should
  still read the following slides for better
  understanding, but I will not go over them in
  class unless you have specific questions.

48
Volcanoes release molten rock from the earths
interior

• An active volcano occurs where magma reaches the
  earths surface through a central vent or a long
  crack, called a fissure.
• Many volcanoes form along the boundaries of the
  earths tectonic plates when one plate slides
  under or moves away from another plate.
• Magma that reaches earths surface is called
  lava.
• Volcanic activity can release large chunks of
  lava rock, glowing hot ash, liquid lava, and
  gases into the environment.

49
Earthquakes are geological rock-and-roll events

• The largest recorded earthquake occurred in Chile
  on May 22, 1960 and measured 9.5 on the Richter
  scale.
• The primary effects of earthquakes include
  shaking and sometimes a permanent vertical or
  horizontal displacement of the ground. These
  effects may have serious consequences for people
  and for buildings, bridges, freeway overpasses,
  dams, and pipelines.

50
Earthquakes are geological rock-and-roll events

• One way to reduce the loss of life and property
  damage is to examine historical records and make
  geologic measurements to locate active fault
  zones.
• Map high-risk areas and establish building codes
  that regulate the placement and design of
  buildings in such areas.
• People evaluate the risk and factor it into their
  decisions about where to live.
• Engineers know how to make buildings and
  structures more earthquake resistant.

51
Earthquakes on the ocean floor can cause huge
waves called tsunamis

• Tsunamis can be detected through a network of
  ocean buoys or pressure recorders located on the
  ocean floor to provide some degree of early
  warning sent through emergency warning centers.
• Between 1900 and 2010, tsunamis killed an
  estimated 280,000 people along the Pacific Ocean.
• The largest loss of life (279,900) occurred in
  December 2004 when a great underwater earthquake
  in the Indian Ocean with a magnitude of 9.15
  caused a tsunami that generated waves as high as
  a five-story building.

52
Earths rocks are recycled very slowly

• The rock cycle is the interaction of physical
  and/or chemical processes that change rock from
  one form to another.
• It takes millions of years for this cycle to
  happen.

53
Some environmental impacts of mineral use

• Metals can be used to produce many products.
• Life cycle of a metalmining, processing, and
  using ittakes enormous amounts of energy and
  water and can disturb the land, erode soil,
  produce solid waste, and pollute the air, water,
  and soil.
• The more accessible and higher-grade ores are
  usually exploited first.
• As they are depleted, mining lower-grade ores
  takes more money, energy, water, and other
  materials, and increases land disruption, mining
  waste, and pollution.

54
There are several ways to remove mineral deposits

• Strip mining is useful and economical for
  extracting mineral deposits that lie in large
  horizontal beds close to the earths surface.
• Area strip mining is used where the terrain is
  fairly flat a gigantic earthmover strips away
  the overburden, and a power shovel removes the
  mineral deposit.
• Contour strip mining is used mostly to mine coal
  on hilly or mountainous terrain.

55
There are several ways to remove mineral deposits

• Mountaintop removal uses explosives, large power
  shovels, and huge machines called draglines to
  remove the top of a mountain and expose seams of
  coal.
• Subsurface mining removes minerals from
  underground through tunnels and shafts.

56
Mining has harmful environmental effects

• Scarring and disruption of the land surface.
• Mountaintop removal destroys forests, buries
  mountain streams, and increases flood hazards.
  Wastewater and toxic sludge, produced when the
  coal is processed, are often stored behind dams
  in these valleys, which can overflow or collapse
  and release toxic substances such as arsenic and
  mercury.

57
Mining has harmful environmental effects

• In the United States, more than 500 mountaintops
  have been removed to extract coal and the
  resulting spoils have buried more than 1,100
  kilometers (700 miles) of stream.
• Surface mining in tropical forests and other
  tropical areas destroys or degrades vital
  biodiversity when forests are cleared and rivers
  are polluted with mining wastes.
• Produces toxic waste material such as lead dust,
  which can cause lead poisoning and irreversible
  brain damage in children.

58
Mining has harmful environmental effects

• Subsurface mining disturbs less land than surface
  mining disturbs, and it usually produces less
  waste material.
• Creates hazards such as cave-ins, explosions, and
  fires.
• Miners often get diseases such as black lung,
  caused by prolonged inhalation of coal dust in
  subsurface mines.
• Causes subsidencethe collapse of land above some
  underground mines.

59
Mining has harmful environmental effects

• Mining operations produce large amounts of solid
  waste and cause major water and air pollution.
• Acid mine drainage occurs when rainwater that
  seeps through a mine or a spoils pile carries
  sulfuric acid to nearby streams and groundwater.
• Mining has polluted about 40 of western
  watersheds in the United States, and it accounts
  for 50 of all the countrys emissions of toxic
  chemicals into the atmosphere.
• Much of this degradation comes from leaking
  storage ponds built to hold a toxic sludge that
  is produced from the mining and processing of
  metal ores.

60
Removing metals from ores has harmful
environmental effects

• Ore mining typically has two components
• Ore mineral, containing the desired metal.
• Waste material.
• Removing the waste material from ores produces
  waste piles called tailings.
• Heating ores to release metals is called
  smelting.
• Without effective pollution control equipment,
  smelters emit enormous quantities of air
  pollutants, including sulfur dioxide and
  suspended particles.
• Chemicals can be used to remove metals from their
  ores.

61
Mineral resources are distributed unevenly

• Five nationsthe United States, Canada, Russia,
  South Africa, and Australiasupply most of the
  nonrenewable mineral resources used by modern
  societies.
• Experts are concerned about four strategic metal
  resourcesmanganese, cobalt, chromium, and
  platinumwhich are essential for the countrys
  economy and military strength. The United States
  has little or no reserves of these metals.

62
Supplies of nonrenewable mineral resources can be
economically depleted

• The future supply of nonrenewable minerals
  depends on two factors
• The actual or potential supply of the mineral.
• The rate at which we use it.
• Minerals may become economically depleted when it
  costs more than it is worth to find, extract,
  transport, and process the remaining deposits.
  Options when this occurs are
• Recycle or reuse existing supplies.
• Waste less or use less.
• Find a substitute or do without.

63
Market prices affect supplies of nonrenewable
minerals

• Geologic processes determine the quantity and
  location of a mineral resource.
• Economics determines what part of the known
  supply is extracted and used.
• An increase in the price of a scarce mineral
  resource can lead to increased supplies and
  encourage more efficient use.
• Standard economic theory may not apply because
  most well-developed countries often use
  subsidies, taxes, regulations, and import tariffs
  to control the supply, demand, and price of
  minerals.
• Most mineral prices are kept artificially low.

64
Is mining lower-grade ores the answer?

• Extraction of lower grades of ore is possible due
  to new earth-moving equipment, improved
  techniques for removing impurities from ores, and
  other technological advances in mineral
  extraction and processing.
• Mining low-grade ores is limited by
• Increased cost of mining and processing larger
  volumes of ore.

65
Is mining lower-grade ores the answer?

• Increasing shortages of freshwaterwhich is
  needed to mine and process some
  mineralsespecially in arid and semiarid areas.
• Environmental impacts of the increased land
  disruption, waste material, and pollution
  produced during mining and processing.
• Can use microorganisms that can break down rock
  material and extract minerals in a process called
  in-place, or in situ, mining or biomining.

66
Can we get more of our minerals from the oceans?

• Some ocean mineral resources are dissolved in
  seawater.
• Low concentrations take more energy and money
  than they are worth.
• Hydrothermal ore deposits are rich in minerals
  such as copper, lead, zinc, silver, gold, and
  some of the rare earth metals.
• Growing interest in deep-sea mining.
• Manganese nodules cover large areas of ocean
  floor.

67
We can find substitutes for some scarce mineral
resources

• Human ingenuity will find substitutes.
• Current materials revolution in which silicon and
  other new materials, particularly ceramics and
  plastics, are being used as replacements for
  metals.
• Finding substitutes for scarce minerals through
  nanotechnology.

68
We can recycle and reuse valuable metals

• A more sustainable way to use nonrenewable
  mineral resources (especially valuable or scarce
  metals such as gold, copper, and aluminum) is to
  recycle or reuse them.
• Recycling has a much lower environmental impact
  than mining and processing ores.
• Cleaning up and reusing items instead of melting
  and reprocessing them has an even lower
  environmental impact.

69
We can use mineral resources more sustainably

• Instead of asking how we can increase supplies of
  nonrenewable minerals, we should be asking, how
  can we decrease our use and waste of such
  resources?
• Since 1990, a growing number of companies have
  adopted pollution and waste prevention programs
  that have led to cleaner production.