Transcript Chapter 24 - PowerPoint

Eric H. Christiansen
Brigham Young University
Easter Island
 Provides excellent
example of impact
of population
growth on
resource use
 Richly forested
island at time of
first human
settlement
 1000 years later,
European explorers
described the
island as desolate
Easter Island
 Fossil evidence gives
detailed history of decline
 Seed, pollen and spore data
show a rich & diverse
environment
 Supported largest diversity
of nesting birds in
Polynesia
 Human settlement lead to
demise of an ecosystem
that could support a large
population
 Deforestation led to
changes in culture and
ecosystems
 Destruction of plant &
animal habitat
 Increased soil erosion
 Lack of wood for ship
building
 Diet shifted from porpoise
to sea birds, chickens &
rats
 Eventually lead to war and
population decline
Fossils Tell History of Island
Mineral Resources
 Mineral resources
comprise any Earth
material used by
industry
 Including metals, oil &
gas, soil etc.
 Mineral deposits
formed by slow
geologic processes
 Rate of use is much
faster than rate of
formation
Mineral Resources
 Resources may be divided
into two categories
 Renewable resources -
replenished over a short
time period


Few mineral resources fall
into this category
Some mineral resources
are recycled
 Nonrenewable resources -
finite & exhaustible over
human time scale
Mineral Resource Formation
 Most mineral resources
are materials that are
in low concentration in
the Earth’s crust
 Mineral must be
concentrated, some
thousands of times, to
form a resource
 Many geologic
processes concentrate
some type of resource
U.S. Petroleum Production and Consumption
Earth Resources
If we must replace petroleum, because of concerns
for energy security (or because we use it all up)
what should we use?
A. Nuclear
B. Geothermal
C. Wind
D. Solar
E. Coal
F. Tidal
Earth Resources
If we must replace fossil fuels because of a concern
with CO2 build up, what energy source should we
use?
A. Nuclear
B. Geothermal
C. Wind
D. Solar
Energy Resources
 Energy resources are also
divided into renewable &
nonrenewable
 Modern society is
dependent on large energy
usage
 Fossil fuels are used at
high rate
 Renewable resources are
not fully developed
 Individually, most
renewable energy
resources can’t meet
demand
US Energy Use
What type of rocks are good sources of
petroleum and natural gas?
A. Metamorphosed sedimentary rocks
B. Granite
C. Basalt
D. Sandstone
E. Conglomerate
F. Shale or mudstone
What type of rocks are good sources of
petroleum and natural gas?
What type of rock makes a good
reservoir for oil and gas?
A. Shale
B. Mudstone
C. Sandstone
D. Granite
What setting would be most
conducive for oil formation?
 A volcanic arc
 A subsiding volcanic island moving off a mantle
plume
 A subsiding sedimentary basin
What rock type is represented in brown?
A. Sandstone
B. Shale
C. Conglomerate
D. Basalt
E. Limestone
F. Granite
Fossil Fuels
 Includes coal, oil and
natural gas
 Produced by plants
growing millions of years
ago
 Organic matter
accumulated and was
buried

Adriatic Sea at http://www.eosnap.com/
Only a small portion
remains to become fossil
fuel
 May be viewed as a form of
solar energy
http://absurdmodernity.files.wordpress.com/2008/12/algae1.jpg
Petroleum & Natural Gas
 Four step processes of
formation
 Source rock with high
organic matter content
 Burial of source rock at
appropriate depth to
form petroleum
 Petroleum or gas must
migrate to become
concentrated
 Must accumulate in
reservoir rock beneath
trap rock barrier
Accumulation of Oil and Gas
3D Seismic Exploration for Oil and Gas
Extraction of Petroleum
 Through wells (holes)
drilled through the trap
rock and into the
permeable reservoir
 Fluids may flow to
surface or may need to
be pumped
 Directional drilling and
multiple wells from
single site
Problems with Petroleum & Natural Gas
 Pumping may cause
subsidence
 Spills are locally
damaging in short
term
 Longevity of resource
is in question
 National security
 CO2 emissions
Coal
 Originated as plant
material in temperate
swamps
 Lush growth forms layers
of peat
 Peat is covered and
undergoes diagenesis

May be metamorphosed
 Carbon content increases
 Deposits restricted to later
part of geologic history
Coal
 Large deposits make it
an important resource
 Geologic mapping has
discovered all major
reserves
 Coal mining may cause
serious environmental
problems


Acid mine drainage
from included pyrite
CO2 & S emissions from
burning
Coal is abundant
Methane Hydrates
 Methane hydrate ices
form in deeper cold
waters of ocean
 Known to cover vast
areas of ocean floor

May contain 2x the C as
oil, gas & coal combined
 Volatile gas may be
difficult to mine
 Methane is a
greenhouse gas accidental release
could impact climate
Renewable Energy Resources
 Solar energy
 Solar radiation is not
constant or evenly
distributed
 Heat used to produce
steam
 May be converted
directly to electricity


Photovoltaic cells
Cells are relatively
inefficient
Renewable Energy Resources
 Hydroelectric
power
 Uses kinetic energy
of flowing water
 Simple technology
is inexpensive and
clean
 Dam construction
disrupts the
regional
environment &
ecology
Hoover Dam, Colorado River, Nevada
Renewable Energy Resources
 Geothermal energy
 Tapping into Earth’s
internal heat
 Heat in sufficient
quantities is often
deep


May be concentrated
around igneous
intrusions
Heat converts water
to steam
 Cheap & long lasting
where available
Geothermal Energy
Nuclear Energy
 Controlled fission of U
produces large
amounts of heat
 Fission is the splitting
of an unstable nucleus
into smaller mass
elements
 Heat used to produce
steam as with most
other energy sources
 Radiation & thermal
pollution are most
serious problems
Nuclear Energy
 Some countries have
developed programs to deal
with these issues
 France produces ~85% of its energy
from 58 nuclear power plants
 For nuclear power to have a high
impact on reducing greenhouse
gases, an average of 12 reactors
would have to be built worldwide
each year until 2030
 Sources of U are commonly
associated with weathering
of rhyolites
 Concentrated in
sedimentary aquifers by
reduction
Olkiluoto nuclear power plant in Eurajoki, Finland.
Photograph: EPR - Finland/Areva
Renewable Energy Resources
Wind energy
 Old technology
 Pollution free and
plentiful
 Not consistent
 Storage for off peak
times is important
 20% of Denmark’s
power comes from
wind energy
How Many Turbines
Would be Needed?
 California's electric
power from fossil-fuel
sources could be
replaced by 6,280 5-MW
turbines in wind speeds
greater than 8.5 m/s.
 This is 3.3 times the
current number of
smaller turbines in
California. (Archer and
Jakobson, 2006)
Objections to Wind Power:
Bird Deaths
 15,000 existing US wind
turbines kill 10,000 to
40,000 birds per year (Bird
Conservancy)
 50 million US bird deaths
per year due to
transmission towers
(Archer and Jacobson,
2006)
 Extrapolating to 5 million
5-MW turbines needed to
satisfy all energy needs
worldwide gives 3 million
to 13 million bird deaths
per year, much less than
transmission towers in the
US alone.
Energy Resources
 Energy resources are also
divided into renewable &
nonrenewable
 Modern society is
dependent on large energy
usage
 Fossil fuels are used at
high rate
 Renewable resources are
not fully developed
 Individually, most
renewable energy
resources can’t meet
demand
US Energy Use
What makes a light bulb?
 Blub: soft glass from silica, trona, lime,
coal, and salt.
 Filament usually of tungsten
 Lead in wires: copper and nickel
 Tie wires: molybdenum
 Stem press wires: nickel-iron alloy core
and a copper sleeve
 Fuse: nickel, manganese, copper and or
silicon alloys
 Gas : nitrogen and argon
 Support wires: molybdenum
 Button and button rod are made of glass
 Base: brass (Cu and Zn) or aluminum
 Remember all the energy used to extract
the materials, to refine them, and to
manufacture, distribute and light the
bulb
Gold: A metallic mineral resource
Gold: Metallic Mineral Resource
 Crustal concentration
0.005 parts per million
 Ore deposit
concentration as low as
0.5 ppm
 Price of Gold ~$1217/oz
(December 2009)
 Typically concentrated
by extraction, flow in a
fluid, and then
precipitation in a “trap”
Carlin Mine, Nevada: www.ecoflight.info
Hydrothermal fluids related to igneous rocks
 Water rich solutions are
heated and/or released
from some cooling
magmas
 Soluble elements (like Au
and S) are concentrated
in these fluids
 Fluids migrate along
fractures
 Eventually Au (or other
minerals) are deposited
as P & T drop or as fluid
reacts with wall rocks
Ores related to Igneous Processes
Gold Mining
Bingham Canyon Cu-Au-Mo Mine, Utah
Bingham Aerial View
Kennecott Utah Copper
Kirsten Thompson
Bingham Copper Contours
Bingham Gold Contours
Bingham Molybdenite Contours
Bingham Canyon Mine, Utah
Kennecott Utah Copper
Kirsten Thompson
Gold Mining
 In all of history, only
161,000 tons of gold have
been mined, barely
enough to fill two
Olympic sized
swimming pools.
 More than half has been
extracted in the past 50
years.
Tectonic Controls on Ore Deposits
In what tectonic setting do you think
porphyry copper-gold deposits form?
A. In ancient rifts related
to mantle plumes
B. In ancient continental
shields
C. In thin layers of
sedimentary rocks
D. In volcanic arcs related
to subduction
Fig. 24.26. Mineral resources & tectonic setting
Geology careers
 Undergraduate degrees
Earth Science Teaching
Junior/High School
 Masters degree
Most commonly required
for other professions
Geoscience as a Career
 According to the National Science Foundation,
there are about 125,000 geoscientists in the US.
 Most are employed by industries related to oil and gas, mining
and minerals and water resources.
 Many geoscientists are self-employed as geological consultants or
work with consulting firms.
 Many work for the federal government or a state government
agency.
 U.S. Geological Survey, Department of Energy, Department of
Agriculture, Forest Service, National Aeronautics and Space
Administration, National Oceanic and Atmospheric Administration,
U.S. Army Corps of Engineers, state geological surveys, and state
departments of environment and resources all employ geoscientists.
Geology Careers: Starting Salaries
 Education
 Oil /Gas Exploration
 Environmental Geo
 Mining Geology
 Government
15%
45%
15%
5%
10%
 University
 Other (Law, MBA)
 Other Science
 Engineering
 MBA (2006 data)
$29,000
$82,500
$45,500
$62,500
$45,000
$52,500
BS
MS
MS
MS
MS
PhD
10%
$47,000
MS
$48 to $66,000
MS
$81,600
MBA
Most from 2007 AGI
Geology Career Preparation
 Other helpful training
 Math
 Chemistry
 Computer Science
 Business
 Student Clubs
 BYU Geology Club
 AAPG
 SEG/SEG
 GSA
 Jobs/Internships
 Companies
 Oil exploration
 Engineering consulting
 BYU Mentored Research
 Volunteers
 USGS,National Park Service
What would I do?
 Computer analysis of
data
 Writing reports
 Meetings
 Laboratory work
 Field work