Transcript Geology, Earth Energy

Geology II: Earth’s Energy
Creation of Energy?
• Two major kinds:
– Kinetic
– Potential
• Energy not created or
destroyed, just
changed in form (first
law of thermodynamics)
• What about energy from geologic /
natural systems?
Types of “Geologic” Energy
• Geothermal
– Hot springs
– Hot Spots
– Hydrothermal Vents
• Radiation
– Natural decay
– Solar
Geothermal Energy
• Geo – Earth
• Thermal – Heat
• Involves water being heated (thermal
energy) and forced upward. If deep
within the earth - some are deeper than
one mile - rocks may block upward
movement causing a build up of pressure
(potential energy).
• When water finds its way to the surface,
the potential energy is converted into
kinetic energy in the form of a geyser or
steam
Geothermal Uses
• Geothermal Power Plants
• Residential Use
• Tourist Attractions (viewing and
swimming/”bathing”)
Geothermal Power plants
Geothermal Power Plants
Around the World
U.S. Geothermal
• Yellowstone Geysers
– Steam Boat Geyser
– Old Faithful
• U.S. is the worlds largest provider of
geothermal electricity production
• Most plants and sources in the U.S. are
located in The Geysers, California
– 22 current geothermal power plants
U.S. Geothermal Hotsprings
Geothermal Hot Spots
Hydrothermal Vents
• Located on the ocean floor
• Release a mixture of gases (methane, sulfur,
helium), minerals (Fe, Zn, Cu, Pb, Co),
nutrients, and extreme heat (750 °F – but they
do not boil due to the extreme pressure on
the ocean floor)
• Provides habitat to a unique array of
organisms
• Mammoth Copper Mines, Cyprus were formed
by hydrothermal vent activity prior to being
uplifted to become dry land
Radiation
•
Types of radiation include:
– Non-ionizing radiation - has
enough energy to move atoms
in a molecule or cause them
to vibrate but not enough
energy to remove electrons
• Radio Waves
• Visible Light
• Microwaves
– Ionizing radiation – So much
energy it can knock electrons
out of atoms (called
ionization).
• Naturally radioactive
elements
• Sun rays and other cosmic
particles from outer space
• X-ray equipment
Radioactive Decay
• A radioisotope’s loss
of radioactivity over
time is measured in
half-lives
• A half-life is the time
it takes one half of
the atoms of a
radioisotope to decay
by emitting radiation
Radon
• Naturally
occurring
radioactive gas
• Second most
frequent cause of
lung cancer (15%
of lung cancer
cases)
• Formed from the
radioactive decay
of uranium in
soil, rock, or
water
Radiometric Dating
• A technique used to determine the age
of materials such as rocks or
archaeological items
• Uses the ratio of the naturally occurring
radioactive isotope compared with the
decay product since
they form (or decay,
and emit beta-radiation) at a constant
rate
Radiometric Dating (cont’d)
• Examples include:
– 238U and 206Pb for 1 MYA – 4.5 BYA
– 235U and 238U for 2 MYA – 2.5 BYA
– 234U and 230Th for a scale of several
hundred thousand years
– 14C and N typically
for dead plants and animals.
Typically used on a scale
of 58,000 to 62,000 years
Radiometric Dating (cont’d)
Sample
Approximate Age
in Years
Cloth wrappings from a mummified bull Samples taken from a pyramid in
Dashur, Egypt. This date agrees with the age of the pyramid as estimated
from historical records
2,050
Charcoal Sample, recovered from bed of ash near Crater Lake, Oregon, is
from a tree burned in the violent eruption of Mount Mazama which created
Crater Lake. This eruption blanketed several States with ash, providing
geologists with an excellent time zone.
6,640
Spruce wood Sample from the Two Creeks forest bed near Milwaukee,
Wisconsin, dates one of the last advances of the continental ice sheet into
the United States.
Bishop Tuff Samples collected from volcanic ash and pumice that overlie
glacial debris in Owens Valley, California. This volcanic episode provides an
important reference datum in the glacial history of North America.
Monzonite Samples of copper-bearing rock from vast open-pit mine at
Bingham Canyon. Utah.
Quartz monzonite Samples collected from Half Dome, Yosemite National
Park, California.
Rhyolite Samples collected from Mount Rogers, the highest point in Virginia.
Pikes Peak Granite Samples collected on top of Pikes Peak, Colorado.
The Old Granite Samples from outcrops in the Transvaal, South Africa.
These rocks intrude even older rocks that have not been dated.
Morton Gneiss Samples from outcrops in southwestern Minnesota are
believed to represent some of the oldest rocks in North America.
11,640
700,000
37,500,000
80,000,000
820,000,000
1,030,000,000
3,200,000,000
3,600,000,000
Highest Naturally
Radioactive Sites in
the World
•
•
Guarapuri, Brazil – White sand
beaches from eroded
monzanite, an ore of thorium (a
radioactive element)
– Measurments up to 175
mSv (millisierverts) per year
(20 mSv is limit for workers
in the nuclear industry)
Ramsar, Iran – on coast of
Caspian Sea. Natural
hotsprings abundant with
radioactive limestone used to
make bricks and masonry for
the area
– Measurements up to 250
mSv
Highest Naturally
Radioactive Sites in
the World (cont’d)
• Paralana Hot Springs,
Arkaroola, Australia –
Water flows through
uranium rich rocks
– Hot springs heated
by radioactive decay,
not geothermal
energy
• Yangjiang, China – Sand
and clay in area, again,
from eroded monzanite