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JMU / Geology / GEOL 102 / What do we use minerals for?

What do we use minerals for?

What do we use minerals for?

Description

Geology 102


What do we use minerals for?



1/10/18

Chapter 1 

System- entity composed of parts, each of which contributes to the function of the  whole

Types of Systems

Open- energy and matter can flow across boundaries (most natural systems) ∙ Ex. A lake (sunlight, rain, evaporation, living organisms)

Closed- only energy can flow across boundaries, matter cannot

∙ Ex. A terrarium (heat energy can enter and leave but the matter inside  cannot leave)

Isolated- neither energy nor matter can flow across boundaries ∙ Ex. Dead cell phone (can’t transmit or receive anything

Dynamic- energy or matter inputs/withdrawals cause the system to change over  time (most natural systems)


How does mining impact the environment?



Static- no change (or net change) occurs

Processes cause changes in systems If you want to learn more check out What is the function of brain stem?

Earth’s Major Systems

Solid Earth- interior

Lithosphere- outer crust  

Pedosphere- outermost part of planet, where most water is

∙ Outermost crust is soil

Biosphere- where living things are

Hydrosphere- all water

Atmosphere

Earth’s major systems have reservoirs of both matter and energy Reservoirs Don't forget about the age old question of How do you know if its polar or nonpolar?
Don't forget about the age old question of What is the difference between an ai and an rda for a nutrient?

Stock- the energy or matter in a reservoir

Flux- any change in energy or matter in a reservoir

∙ Positive flux- adding energy or matter


How do we know what the world is like?



∙ Negative flux- reducing energy or matter

Feedbacks

Reinforcing (positive) feedback- promotes further change

∙ Growing ice sheet reflects more sunlight into space which causes the  temperature to cool down  

Balancing (negative) feedback- reverse direction of change

∙ Carbon dioxide in atmosphere traps heat and causes temperature to rise,  warmer temperature allows atmosphere to hold more water vapor, increased  cloud cover causes temperature to fall

Week 2 Notes

1/17/18

How do we know what the world is like?

World’s deepest mine is in South Africa- 3.9 km (2.4 miles) deep, temperature at the bottom is more than 130 degrees F

Deepest hole in Russia more than 7 miles deep

Studying earthquakes- we know we have a solid inner core and liquid outer core Drilling data We also discuss several other topics like What are the two behaviors of inertia?

Geophysics- making mini-earth quakes to create a sonogram of the inside of the  Earth We also discuss several other topics like What refers to the middle of an interval in a grouped frequency distribution?

Studying rocks that formed deep in the Earth- pressure, temperature,  chemistry of rocks

What we think the Earth looks like

Core- rich in metal

∙ Solid inner core

∙ Liquid outer core

Mantle- mixed materials in more equal amounts

∙ Asthenosphere- moveable material, weak soft rock

∙ Mesosphere- denser, more rigid rock

Crust (Lithosphere) - rich in oxygen, cool, hard rock

∙ Oceanic- more dense, thinner

∙ Continental- less dense, thicker

Continental Drift

Alfred Wegener- studied climate, came up with the idea of continental drift

∙ Published this idea in 1912 If you want to learn more check out How are impressions different from ideas?

∙ Continents were not fixed in place and had once fit together

∙ His ideas were rejected by most scientists and he had no process to explain  how the continents were moving

Evidence

∙ Continents seemed to fit together

∙ Glacial sediment found on several continents  

∙ Land fossils from the same time period found on different continents ∙ Matching crust and mountain belts on different continents

After WWII people wanted to better understand the ocean Surveys showed that the ocean floor wasn’t flat

∙ trenches

∙ mid-ocean ridges

∙ fracture zones  

Heat flow is not the same across the ocean

Eruptions of gas and metals occurred at mid ocean ridges

Ocean crust records periodic reversals in the earth’s magnetic field, showing that  ocean crust is constantly forming

What process drives Continental Drift

Mantle Convection- there was a transfer of heat energy within the mantle in  circular patterns (cells)

∙ The relationship between different cells of convection could explain the  movement of continents  

∙ Convergent and divergent cells

Plate Boundaries

Divergent- convection cells pull Earth’s crust apart, creating new ocean crust Convergent- convection cells push Earth’s crust together

∙ Subduction- one piece of crust gets pushed down under the other and back  into the mantle to be recycled

∙ if this happens with an oceanic piece of crust and a continental piece of crust, the oceanic piece will usually be pushed under

∙ If they continue for long enough it can create a large land mass ∙ Can create mountain ranges

Transform-Fault- the plates move alongside each other horizontally  

Earthquakes

Focus- where the earthquake actually occurs

Epicenter- the ground above the focus

You can triangulate the location of an earthquake with seismographs ∙ P waves (faster) and S waves (slower)  

Earthquakes happen all the time and they all release energy

The amount of energy released during an earthquake is measured with magnitude  (1-12)

∙ The amount of energy released goes up 1000x every 2 numbers of  magnitude  

∙ magnitude 2 = 56 kilograms of explosive, magnitude 4 = 56,000 kilograms of explosive

The location of earthquakes are related to plate tectonics

∙ Deeper earthquakes are normally caused by convergent while more shallow  earthquakes are usually caused by divergent

Most earthquakes occur along faults

Normal faults- one piece of the Earth’s crust falls in relation to another ∙ Occur with divergent, getting pulled apart

Reverse fault- one piece of the Earth’s crust gets pushed above the other ∙ Occur with convergent, being pushed together

Strike-slip fault- two pieces of crust move laterally in different directions

∙ Right-lateral- the opposite side moves to the right

∙ Left-lateral- the opposite side moves to the left

How earthquakes work

Stress builds up between plates

Local rock strength determines how much stress there can be before it is released

An incomplete release of stress means the time between earthquakes will be  shorter than if there was a complete release of stress

Plates shifting in one area can reduce stress in another area

Frequent earthquakes can reduce local rock strength

The impact of an earthquake on humans is measured by intensity Intensity is measured in roman numerals on a 12 point scale (I-XII)

An earthquake has 1 magnitude but multiple intensities depending on where you  are

Steps to mitigate damage

Building homes to a higher standard

∙ Diagonal bracing

∙ Reinforced framing

∙ Bolting structures into foundation

Within a home

∙ Brace heavy furniture

∙ Know where water/gas shutoffs are

Have a survival kit

Drop, cover, hold on (will be on exam)

Week 3 Notes

Elements Minerals and Rocks

Elements- substances that cannot be changes into other substances by normal  chemical methods

∙ Basic building blocks of minerals

∙ >100 known (92 naturally occur)

Oxygen, silicon, aluminum and iron are the most abundant elements in Earth’s crust by weight (in that order)

Minerals- naturally occurring, inorganic solids with an ordered internal structure  and a definite chemical composition

∙ Building blocks of rocks

∙ Silicates are the most common type of minerals, they form the majority of  rocks on earth

Minerals are identified by physical properties

∙ How crystals grow

∙ Cleavage- how it breaks, planes of weakness

∙ Color

∙ Luster- glassy, metallic

∙ Diagnostic streak- the color it leaves behind when scratched on a hard  surface

∙ Hardness

o Mohs Hardness scale (1-10 from softest to hardest)

Rocks- naturally occurring solid aggregates of minerals, or in some cases, non mineral solid matter

∙ Can be composed of one mineral or several

o Granite contains orthoclase feldspar, quarts, biotite, and plagioclase  feldspar

∙ Identity is determined by process of formation, texture, and  composition

3 Major Rock Types:

Igneous- form from the melting of rocks and then crystallization of magma  

∙ Extrusive (volcanic)- associated with volcanic activity, form when magma  reaches the earth’s surface and cools rapidly; tend to have smaller crystals,  fine grain texture

o Basalt

o ash

∙ Intrusive (plutonic)- magma cools deeper in earth’s crust at a much slower pace; course grain rock with larger crystals

o granite

Sedimentary- recycled from other broken up rocks, textures can tell us about the  Earth over time

∙ clastic- formed when existing rocks get broken up and are carried by wind or water and then redeposited into the earth

∙ chemical- form when elements get dissolved in water and the water  evaporates over time until the minerals become more concentrated o salt

o limestone

∙ biologic- formed from dead organisms  

o coal

o coquina

Metamorphic- buried deeply in the earth’s crust, under high pressures and  temperatures causing the minerals to change (not melt)

∙ Foliated- minerals align in layers due to pressure, layers called foliation  

Regional metamorphism- occurs at moderate to deep levels under medium to  ultra-high pressures and high temperatures; at convergent plate boundaries

Mineral Resources

Every American born will need 2.96 million pounds of minerals, metals, and fuels in  their lifetime

Sand, gravel and stone are the most used minerals  

Minerals are a global commodity

What do we use minerals for?

∙ Buildings- (exterior and interior) brick, granite, shingles, drywall ∙ Roads- gravel, asphalt, concrete  

∙ Automobiles- iron, steel, plastic, petroleum

∙ Electronics- batteries, wires, screens

Mineral deposits- locally rich concentrations of minerals

Mineral reserves- mineral deposits that are economically feasible for extraction Ores- reserves of metallic ore minerals

Concentration- the amount of an element or mineral that is present in deposit;  sometimes shown as percentage (grade)

Concentration factor- ratio of abundance in deposit to average abundance in  continental crust

Critical minerals- strategic minerals to make a country less reliant on other  countries  

How are minerals located?

∙ Testing soil

∙ Using equipment to test magnetism of soil

∙ Drilling

How are minerals recovered?

∙ Open pit mining- the most common way to mine

∙ Dredging material

∙ Underground mining

How does mining impact the environment?

∙ Most mines generate waste rock or “tailings”-  

o they can be unsightly but not hazardous

o can be hazardous, can affect streams and water quality

∙ abandoned mines can be hazards

∙ There are regulations but can still have an impact on natural environment

o Required to be reclaimed

o Required to protect water quality

o Modern mining funds the cleanup of abandoned mines

Week 4

Volcanoes

There are ~1,300 active/potentially active volcanoes on Earth

Location of volcanoes are related to plate tectonics

80% of volcanoes occur at convergent plate boundaries

Some volcanoes occur at “hot spots”

How Volcanoes work

Magma reservoir- where magma is stored

Central vent- where the magma mainly comes out

Side vents- magma will go where it is easiest, so it might not always go out the  main vent

Lava, ash, and rock are ejected, there are different kind of eruptions, some are more explosive with ash and gas, some are less explosive with more flowing lava

Ash can travel a long distance from the eruption and affect places in the world far  away from the volcano  

Types of Volcanoes

Cinder cones

∙ Smallest and most numerous cones

∙ Built from pyroclastic materials- tephra

∙ Erupting lava falls around vent  

∙ Local and short-lived, one-time events

∙ Paricutin cinder cone in Mexico

Shield Volcanoes

∙ Gentle outpourings of mafic lava (basalt) from central vent or conduit ∙ Far broader that high- “shield”

∙ Hawaiian Islands (hotspot volcanism)

o Built up from seafloor eruptions

Stratovolcanoes

∙ Stratified layers built from combination of effusive and explosive activity  (composite cones)

∙ Form on landward side of subduction zones

o Descending oceanic crust melts and rises

o Magma becomes enriched with silica and gases

o Andesitic and rhyolitic volcanism: explosive

Caldera

∙ Depression in landscape

∙ Magma empties out and creates a void where the earth’s crust falls in VEI- scale (1-8)

Impact on Climate

Large eruptions lead to regional and global cooling

∙ Iceland volcano 1783-1784 cold winter

∙ Tambora 1815 created global cooling and famine

Particles reach upper atmosphere and reflect solar radiation back to space

∙ Residence time of 1-2 years

∙ Dust Veil Index

Dangers

Lahars- mudflow, snow is melted very quickly and creates a mudslide

∙ Volcanic debris flow

∙ Water from precipitation, melting snow, lake of river mixes with debris and  flows downslope

∙ Can be triggered by volcanic eruption- Mount St. Helens in 1980 Landslides- debris

Fumaroles- gases emitted, can be deadly

Acid rain- can affect crops

Lava flows- don’t move very fast, but can destroy property and catch people off  guard

Ash- can suffocate people, ruin crops

Pyroclastic flows- all the material coming down the side of the volcano ∙ Mix of hot gases and pyroclastic material

∙ Move rapidly

∙ Nuee ardente

∙ Mount St. Helens: deaths and destruction

∙ Mount Pelee, 1902; 30,000 deaths

∙ Mount Vesuvius buried Pompeii, A.D. 79

Most Volcanoes in the US are in the west

Geologic Time

 We have learned a lot about time from rocks

∙ More layers = the older it is

∙ What the layers are made of  

Law of Superposition- if something is in a layer that is underneath something  else, it is usually older

Law of cross-cutting relationships- if something goes across something else,  the one that crosses is younger than what it crosses

Law of fossil succession- evolution, an organism does not go extinct and then  come back again, so if a fossil is found of an organism, it is older than when the  organism went extinct

Age Dating

Relative Dating- determine the sequence of events using the 3 laws

Absolute Dating- obtain an actual date, takes advantage of natural process of  radioactive decay where a radioactive isotope (parent) spontaneously gains or loses a particle, causing it to become another element (daughter)

∙ Radiometric dating- radioactive element decays and releases particles; can stay the same or become a new element

o Half-life- time requires for ½ of atoms to decay  

o Different compounds have different half-lives and can be used for  different age ranges

Today we are in the:

∙ Phanerozoic Eon

∙ Cenozoic Era

∙ Quaternary Period

∙ Recent/ Holocene Epoch

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