energy & resources renewable & nonrenewable
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Energy & Resources Renewable & Nonrenewable. Chapter 15. Geology & Mineral Resources. GEOLOGIC PROCESSES. The earth is made up of a core, mantle, and crust and is constantly changing as a result of processes taking place on and below its surface. The earth’s interior consists of: - PowerPoint PPT PresentationTRANSCRIPT
Energy & Resources Renewable & Nonrenewable
Chapter 15
Geology & Mineral Resources
GEOLOGIC PROCESSES• The earth is made up of a core, mantle, and crust and
is constantly changing as a result of processes taking place on and below its surface.
• The earth’s interior consists of:– Core: innermost zone with solid inner core and molten
outer core that is extremely hot.– Mantle: Thickest zone: a rigid outer part, but underneath
is asthenosphere that is melted pliable rock that flows in convection currents
– Crust: Outermost zone which underlies the continents and oceans
– Lithosphere: combination of crust and outer part of mantle
The Earth’s Crust
• The Earth’s crust is relatively thin relative to the rest of the planet.25-70 km thick below the continentsaround 10 km thick below the oceans.
• The crust is rich in oxygen and other lighter minerals such as silicon, calcium and aluminum and is less dense than the mantle. The crust rides over the mantle causing the formation of oceans, mountains and volcanoes.
Lithosphere
AsthenosphereContinental crust
The continental crust is made up of igneous, metamorphic, and sedimentary rocks. It is not recycled within the Earth as often as oceanic crust, so some continental rocks are up to 4 billion years old.
Oceanic crust
More than two thirds of the Earth’s surface is composed of oceanic crust. Oceanic crust is continually formed from mantle material and so is relatively young. Even the oldest parts of the ocean floor are no more than 200 million years old.
The Lithosphere‣ The lithosphere comprises the crust and the upper most region of the mantle.
‣ The lithosphere carries the outer rock layer of the Earth, which is broken up into seven large, continent-sized tectonic plates and about a dozen smaller plates
‣ The lithosphere overlies the hotter, more fluid lower part of the mantle, the asthenosphere.
ContinentalCrust
Oceanic Crust
Approx. 70km
Asthenosphere
Approx. 250km
Mantle
Lithosphere
Mohorovicicdiscontinuity
GEOLOGIC PROCESSES
• Huge volumes of heated and molten rack moving around the earth’s interior form massive solid plates that move extremely slowly across the earth’s surface.– Tectonic plates: huge rigid plates that are moved
with convection cells or currents by floating on magma or molten rock.
Fig. 15-3, p. 337
Spreading center Ocean
trench
Plate movement
Subduction zone
Oceanic crust
Continental crust
Continental crust
Material cools as it reaches
the outer mantle
Cold dense material falls back through
mantleHot
material rising
through the
mantle
Mantle convection
cell
Two plates move towards each other. One is subducted back into the mantle on a falling convection current.
Mantle
Hot outer core Inner
core
Plate movement
Collision between two continents
Tect
onic
plat
e
Oceanic tectonic
plateOceanic tectonic plate
Oceanic crust
• Plate tectonics is the theory explaining the movement of the plates and the processes that occur at their boundaries.
Plate Movement• Heat from the mantle drives two kinds of
asthenospheric movement:convection
mantle plumes
• Plate motion is also partly driven by the weight of cold, dense plates sinking into the mantle at trenches.
• This heavier, cooler material sinking under the influence of gravity displaces heated material that rises as mantle plumes.
IRON-NICKELCORE
New crust createdat spreading ridge
Mantle plume of hotter material rising from near the core
Crust melts as itdescends into mantle
Crust cools and sinks into mantleunder the influence of gravity
Heating andcooling causesconvection
Fig. 15-2, p. 336
Volcanoes
Folded mountain belt
Abyssal floor
Oceanic ridge
Abyssal floor TrenchAbyssal hills
Craton
Abyssal plain
Oceanic crust (lithosphere)
Continental shelf
Abys
sal p
lain
Continental slope
Continental rise
Continental crust (lithosphere) Mantle (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
Fig. 15-4a, p. 338
EURASIAN PLATENORTH AMERICAN PLATE
ANATOLIAN PLATE
JUAN DE FUCA PLATE
CHINA SUBPLATE
CARIBBEAN PLATE
PHILIPPINE PLATE
ARABIAN PLATEAFRICAN
PLATEPACIFIC PLATE SOUTH
AMERICAN PLATENAZCA
PLATEINDIA-
AUSTRALIAN PLATE
SOMALIAN SUBPLATE
ANTARCTIC PLATE
Divergent plate boundaries
Convergent plate boundaries
Transform faults
Earth’s Major Tectonic Plates
Pacific Plate
• The Pacific plate is off the coast of California. Lots of volcanoes and earthquakes occur here.
• “California will fall into the ocean” idea. • It is the largest plate and the location of the
ring of fire.
Ring of Fire
TrenchVolcanic island arc Craton
Lithosphere
Subduction zoneLithosphere Lithosphere
Asthenosphere Asthenosphere Asthenosphere
Divergent plate boundaries Convergent plate boundaries Transform faults
Rising magma
The extremely slow movements of these plates cause them to:
1. grind into one another at convergent plate boundaries 2. move apart at divergent plate boundaries 3. slide past at transform plate boundaries.
Huge pressures created are released by earthquakes & volcanoes
Plate Boundaries
Convergent – the plates push together by internal forces. At most convergent plate boundaries, the oceanic lithosphere is carried downward under the island or continent (subduction zone.) Earthquakes are common here. It also forms an ocean trench or a mountain range.
Convergent Plates: push together–Plate attrition occurs at convergent boundaries marked
by deep ocean trenches and subduction zones. The Pacific plate is a convergent plate.
Deep sea trench
Active volcano
Mountain range
Continental crustOceanic crust
MantleSubducting plate
Convergent plate boundary Divergent plate boundary
When an oceanic plate collides with a continental plate, it sinks in to the mantle
and eventually melts.
Boundaries• Divergent – the plates move apart in
opposite directions. Creates oceanic ridges
Divergent Plates–The size of the plates is constantly changing, with some
expanding and some getting smaller.
–These changes occur along plate boundaries, which are marked by well-defined zones of seismic and volcanic activity.
–Plate growth occurs at divergent boundaries along sea floor spreading ridges such as the Mid-Atlantic Ridge and the Red Sea.
Divergent plate boundary
Continental rift zone
The changing convection currents inside the Earth can cause new boundaries to form and old ones to disappear.
Magma upwellings through fractures cause plates to diverge.
Divergent plate boundary
Sea floor Spreading• Sea floor spreading occurs as magma wells up
from the mantle below, forcing the plates apart. • As the new rock cools and solidifies it picks up
and preserves the direction of the Earth’s magnetic field.
On average the Earth’s magnetic field reverses once every million years. This leaves magnetic bands in the crust.
New rock on either side of the ridge has the same magnetic information.
This shows clear evidence of sea floor spreading and plates tectonics.
Plate Boundaries• The Earth’s major
earthquake and volcanic zones occur along plate boundaries.
• The movements of plates puts crustal rocks under strain.
• Faults are created where rocks fracture and slip past each other.
• Earthquakes are caused by the energy released during rapid slippage along faults.
New Zealand’s alpine fault is visible from space, marking a transform boundary between the Indo-Australian plate and the Pacific plate.
Continental Boundaries
• Where continental plates meet, the land may buckle and fold into mountain ranges.
• The highest mountains on Earth, the Himalayas, were formed in this way as the subcontinent of India collided with continental Asia.
• Few volcanoes form in these areas because the continental crust is so thick.
Boundaries• Transform – plates slide
next or past each other in opposite directions along a fracture.
• California will not fall into the ocean!
Transform Boundaries
• Plates may slide past each other at transform boundaries
• Plate size is not affected because there is no construction or destruction of material at these boundaries. However, they are responsible for large earthquakes.
• Pressure from the plates causes the boundary to lock in position and earthquakes occur when the rock gives way to release the pressure.
Faultline movement after an earthquake
San Andreas fault
Image: NASA
Photo: Wiki commons
GEOLOGIC PROCESSES
• The San Andreas Fault is an example of a transform fault.
Figure 15-5
Importance
• Plate movement adds new land at boundaries, produces mountains, trenches, earthquakes and volcanoes.
• Important part of recycling earth’s crust, forming mineral deposits
Changing Earth’s surface• Internal processes – rely on heat from earth’s
interior – tend to build up earth’s surface • External processes – rely on energy from sun
and earth’s gravity – tend to wear down earth’s surface– Erosion: Wind, water, glaciers, human activities
especially deforestation (roots hold soil in place)– Weathering: break down rocks, forms soils
• Physical – wind, rain, water freezing & expanding• Chemical – reactions with water, acids, gases• Biological – tree roots, lichen
Sediments eroded from continents and compressed into sedimentary rock can be
later lifted and exposed in mountains
Igneous rocks, such as basalt, form a major component of the crust and are essentially
unchanged since their formation.
The Earth's persistent oceans of liquid water cycle moisture through the atmosphere to the
land and back again.
Water, as rain, drains to rivers and lakes, which flow back to the ocean eroding the
landscape in the process.
The Earth’s Crust
The Rock Cycle
The interaction of physical and chemical processes that turn 1 type of rock into another
The slowest of the earth’s cycles; takes millions of years
Fig. 15-8, p. 343
ErosionTransportation
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
The Rock Cycle
Magma
Intrusiveigneous rock
LAND
Metamorphicrock
SEA
The rock cycle constantly redistributes material within and at the Earth's surface over millions of years by melting, erosion, and metamorphism. It is the slowest of the Earth's cycles and is responsible for concentrating the mineral resources on which humans depend.
MA
NT
LE
CR
UST
SUR
FAC
ER
OC
KS FO
RM
ED
AT TH
E E
AR
TH
'S SUR
FAC
ER
OC
KS FO
RM
ED
IN T
HE
EA
RT
H'S IN
TE
RIO
R
Extrusiveigneous rock
cooling andcrystallization
burial andrecrystallization
deep burial
metamorphic rock
deep burial
metamorphic rockmelting
cooling andcrystallization
uplift anderosion
uplift anderosion
weathering, exposure, andtransport, followed by burial
Sedimentaryrock
burial andrecrystallization
Steps
The Rock Cycle• The Earth's rocks are grouped
together according to the way they formed as:
igneous
metamorphic
sedimentary rocks
• Igneous rocks are created by volcanism and may form above the surface as volcanic rocks or below the surface as plutonic rocks.
• Heat and pressure within the Earth can transform pre-existing rocks to form metamorphic rocks.
• When rocks are exposed at the surface, they are subjected to weathering and erosion and form sediments.
Types of Rock• The Earth's crust is made up of solid, naturally
occurring assemblages of minerals called rocks.
• The huge diversity of the Earth's rocks has developed over thousands of millions of years through:
igneous activity (volcanism) main source of mineral resources
metamorphism (changes in form)
sedimentation (formation of sediments and sedimentary rocks)
Igneous rocks Metamorphic rocks Sedimentary rocks
Types of Rock
• Igneous rocks solidify from volcanic magma They vary in composition from basalt to granite and in texture from rapidly cooled glasses, such as obsidian, to slowly cooled coarse grains, such as granite.
Obsidian Marble Conglomerate
SandstoneSchistGranite
‣ Metamorphic rocks result when pre-existing rock is transformed by heat and pressure. Metamorphic rocks are classified by texture and composition. Examples include gneiss, slate, marble and schist.
‣ Sedimentary rocks form when sediments accumulate in different depositional environments and then become compressed into brittle, layered rocks, e.g. shale, sandstone, limestone, and conglomerate.
Igneous• Description – forms the bulk of the earth’s
crust. It is the main source of many non-fuel mineral resources.
• Classification – – Intrusive Igneous Rocks – formed from
the solidification of magma below ground
–Extrusive Igneous Rocks – formed from the solidification of lava above ground
Rock Classification
Igneous (Continued)
• Examples – Granite, Pumice, Basalt, Diamond, Tourmaline, Garnet, Ruby, Sapphire
Sedimentary
• Description – rock formed from sediments. Most form when rocks are weathered and eroded into small pieces, transported, and deposited in a body of surface water.
Clastic – pieces that are cemented together by quartz and calcium carbonate (Calcite).
Examples: sandstone (sand stuck together), Conglomerate (rounded & concrete-looking) and Breccia (like conglomerate but w/ angular pieces)
Sedimentary (Continued)• Nonclastic –
–Chemical Precipitates – limestone precipitates out and oozes to the bottom of the ocean (this is why there is a lot of limestone in S.A.)
–Biochemical Sediments – like peat & coal–Petrified wood & opalized wood
Metamorphic
• Description – when preexisting rock is subjected to high temperatures (which may cause it to partially melt), high pressures, chemically active fluids, or a combination of these
• Location – deep within the earth
Dynamic Metamorphism – earth movement crushes & breaks rocks along a fault. Rocks may be brittle- (rock and mineral grains are broken and crushed) or it may be ductile- (plastic behavior occurs.)
Rocks formed along fault zones are called mylonites.
Examples: • Contact Metamorphism- rock that is next to
a body of magmaEx. limestone under heat becomes marble
through crystallizationLimestone -> marble
sandstone -> quartzite
shale -> hornfelds (slate)
Metamorphic (Continued)
–Regional Metamorphism – during mountain building; great quantities of rock are subject to intense stresses and heat• Ex. cont. shelves ram together
Progressive Metamorphism – One form of rock changing into another
shale->slate->schist->gneisscoal->graphitegranite->gneiss
MineralsMineral: element or compound occurs naturallyMineral resource: concentration that can be extractedConsidered Nonrenewable Essential for modern lifeMetallic: Aluminum, gold, copperNonmetallic: sand, gravel, limestoneDistribution of mineral resources is uneven4 strategic metal resources: Manganese, Cobalt,
Chromium, and platinum are critical and come from unstable countries in Africa – must stockpile
Eventually will run out
Resources
• Many resources are extracted from the different layers of the Earth and some minerals are mined for their uses economically:
Coal, oil, and natural gas are all a mined resource
Uranium is mined for nuclear reactions
Gold, silver, platinum are precious metals and are used commercially
Bauxite is used for aluminum production and are used commercially
OxygenThe most abundant element in Earth’s crust
Nitrogen:The most abundant element in Earth’s atmosphere
Iron:The most abundant element in the Earth’s core. Core also contain nickel.
Specific Resources & Their Uses • Limestone – abundant locally, formed from layers of
seashells and organisms under pressure as they were covered; used in sidewalks, fertilizers, plastics, carpets, and more
• Lead – used in batteries and cars• Clay – used to make books, magazines, bricks, and
linoleum Gold – besides being used as money and for jewelry,
gold is used in medicine (lasers, cauterizing agents) and in electronics (circuits in computers, etc.)
Texas
• Central – limestone, tin, clay, lead, garnets, freshwater pearls, amethysts, calcium carbonate
• West – talc, mercury, silver, petroleum, sulfur• East – lignite coal, petroleum• South – lignite coal, petroleum, uranium, limestone• North – helium, uranium, petroleum, bituminous
coal
United States
• Central – diamonds (Arkansas), bituminous coal
• West – bituminous and subbituminous coal, gold, silver, copper
• East – anthracite coal, bituminous coal• South – some gold (SC), bituminous coal• North – bituminous coal, some gold (SD, WI)
ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES
• The extraction, processing, and use of mineral resources has a large environmental impact.
Figure 15-9
Natural Capital Degradation
Extracting, Processing, and Using Nonrenewable Mineral and Energy Resources
Steps Environmental effects
Mining Disturbed land; mining accidents; health hazards, mine waste dumping, oil spills and blowouts; noise; ugliness; heat
Exploration, extractionProcessing
Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat
Transportation, purification, manufacturingUse
Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat
Transportation or transmission to individual user, eventual use, and discarding
ENVIRONMENTAL EFFECTS OF USING MINERAL RESOURCES
• Minerals are removed through a variety of methods that vary widely in their costs, safety factors, and levels of environmental harm.
• A variety of methods are used based on mineral depth.– Surface mining: shallow deposits are removed.– Subsurface mining: deep deposits are removed.
Methods• Surface Mining
– Description – if resource is <200 ft. from the surface: Machines and explosives are used to break up & remove the topsoil and rocks. This is called the overburden. Remove the resource, reclamation follows
– Benefits – cheap, easy, efficient– Costs – tears up the land, byproducts produce an acid
that can accumulate in rivers and lakes
Surface Mining• Resource that is near the surface can be economically extracted using
open cuts in the earth.
• The alteration of the land and production of acid mine drainage can lead to pollution of waterways and aquifers. Abandoned mines can also leach acid drainage by rainwater.
Coal seams exposed
Highly erodible highwall remains
Land provides economic and
technical difficulties
Open-pit Mining• Machines dig
holes and remove ores, sand, gravel, and stone.
• Toxic groundwater can accumulate at the bottom.
Figure 15-11
Area Strip Mining• Earth movers strips
away overburden, and giant shovels removes mineral deposit.
• Often leaves highly erodible hills of rubble called spoil banks.
• Regrowth of vegetation is slow
Figure 15-12
Contour Strip Mining• Used on hilly or
mountainous terrain.
• Unless the land is restored, a wall of dirt is left in front of a highly erodible bank called a highwall.
Figure 15-13
Mountaintop Removal• Machinery &
explosives remove the tops of mountains to expose coal.
• The resulting waste rock and dirt are dumped into the streams and valleys below.
• Causes extensive environmental damage
Figure 15-14
Surface Mining Control & Reclamation Act of 1977
• Requires mining companies to reclaim (restore) surface-mined land
• Most cases only partly successful & take decades
• Reclamation– Description – returning the rock layer
(overburden) and the topsoil to a surface mine, grading, fertilizing and planting it
– Benefits – restores land to good condition– Costs – expensive, time-consuming
Methods (Continued)• Underground Mining
– Description – digging a shaft down to the resource, using machinery (and people) to tear off and remove the resource
– Benefits – can get to resources far underground, disturbs less land, creates less waste
– Costs – leaves much of the resource in the ground, more expensive, more time-consuming, more dangerous
• Two main methods:
room and pillar mining
long wall mining• Room and pillar mining removes
blocks of the coal seam while leaving others to act as pillars to keep the roof stable.
• Long wall mining uses machines that move along the length of the coal face. The removed coal falls onto a conveyor that takes it to the surface.
As the machine moves forward the tunnel behind it is allowed to collapse.
Photo: Eickhoff Maschinenfabrik and Eisengießereihttp://www.eickhoff-bochum.de/de/
Underground Mining
Coal Mine
Long wall mining
Coal crusherProcessing plant Silo
Ventilation shaft and elevator
Coal conveyor
PillarsRoom and pillar mining
Mining Impacts• Scarring / disruption of land• Collapse of land above underground mines
(subsidence)• Pollution
– Produces more toxic air emissions than any other industry
– Acid mine drainage pollutes water supplies– Processing ore releases mercury & arsenic, cyanide:
companies have declared bankruptcy & walked away leaving toxic superfund sites
• Produced ¾ of all US solid waste: 3 tons of waste is generated to produce 1 gold ring
Nonrenewable Resources• Definition – things human use that have a limited
supply; they cannot be regrown or replenished by man
• Depletion time: economically depleted when is costs more to obtain than worth.
• At that point, 5 choices:– Reduce– Reuse– Recycle– Find a substitute– Do without
Sustainability
• Definition – prediction of how long specific resources will last; ex. we have a 200 year supply of coal in the U.S.
• Knowing this helps people make decisions in resource use
• Problems – these are only predictions; they may not be accurate
Conservation
• Definition – using less of a resource or reusing a resource, ex. refilling plastic laundry jugs, reusing plastic bags, etc.
• Part of the solution• Problems – this requires a change in our
lifestyle and some people will resist.
Dealing with Nonrenewable Resources
Recycling
• Examples – aluminum, glass, tin, steel, plastics, etc.
• Part of the solution• Problems – recycling a resource can costs more
than using the raw material; we don’t have the technology to recycle everything, people are resistant, need a market for recycled material
Fig. 15-18, p. 351
Solutions
Sustainable Use of Nonrenewable Minerals
• Do not waste mineral resources.
• Recycle and reuse 60–80% of mineral resources.
• Include the harmful environmental costs of mining and processing minerals in the prices of items (full-cost pricing).
• Reduce subsidies for mining mineral resources.
• Increase subsidies for recycling, reuse, and finding less environmentally harmful substitutes.
• Redesign manufacturing processes to use less mineral resources and to produce less pollution and waste.
• Have the mineral-based wastes of one manufacturing process become the raw materials for other processes.
• Sell services instead of things.
• Slow population growth.