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95 Cards in this Set
- Front
- Back
Simple 3 part composition of the earth
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Crust-Mantle-Core
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Lithosphere
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Crust and upper part of mantle
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Asthenosphere
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Less rigid upper part of mantle. Material melts or nearly melts here. Rocks lose strength and become plastic here.
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Mesosphere
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Strong, rigid mantle area. High pressure at this depth offsets the effect of high temperature
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Solid Inner Core
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Dense part of core
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Liquid Outer Core
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Circulation of this part of the core generates Earth's magnetic field. Flows because of heat loss from the core and rotation of the Earth.
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Atmosphere
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-Small fraction of the planet’s mass (less than .01%)
-Feedback with life -Chemical reactions at the surface, photosynthesis -Transports H2O from ocean to land -Transports heat -Agent of evaporation, erosion, etc -Buffers temperature of earth |
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Hydrosphere
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-Definition: total mass of water of surface of our planet
-Covers about 71% of the surface -98% in oceans -Water permitted life to evolve and flourish; every inhabitant on Earth is directly or indirectly controlled by it -Necessary for life -Regulates climate -Transfers heat/mass -Most important erosion agent on land -Trap for sediment |
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Biosphere
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-Definition: the part of the earth where life exists
-Consists of more than 1.6 million described species, 3 million more not yet described -Uneven, more biomass/species near the equator (warm and wet) -Fossil fuels from biosphere -Model for oil/gas environment -Model for environment of past life -Model for sedimentary rocks -Role of life in evolution of crust, atmosphere, hydrosphere -Main factors controlling the distribution of life on our planet are temperature, pressure, and chemistry of the local environment -Formed all the Earth’s coal, oil, and natural gas -Much of the rock in Earth’s crust originated in some way from biological activity |
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Crust
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-Elevation difference between ocean and continent
-Water runs downhill to basins -Continental crusts and oceanic crusts |
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Continental Crust
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Include shields, stable platforms, and folded mountains
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Shields
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-complex of metamorphic rocks and a variety of igneous rocks
-the upper surface is flat and commonly eroded to near sea level -complexly deformed ancient crystalline rocks exposed at surface -also called basement rocks, basement complex -low relief (elevation difference between the low and the high spots), few 100’s of meters elevation, local relief – variability resistant rocks -complex structure and rock type |
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Stable Platform
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-no major tectonism
-shield + veneer of sedimentary -flat lying sedimentary rocks (broad domes, basins) -craton -when a basement complex is covered with a veneer of sedimentary rocks |
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Craton
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the stable continental crust, including the shield and stable platform area
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Basement complex
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rocks of shields are high deformed igneous and metamorphic rocks, covered with a layer of horizontal sedimentary rock
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Folded Mountains
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-rock resistant to erosion, folded, intruded
-along continental margins -when eroded, form shield, basement -less dense than ocean -ancient -deformed by horizontal stress during slow collision between two lithospheric plates |
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Oceanic Crust
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Includes oceanic ridge, abyssal floor, seamounts, trenches, and continental margins
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Oceanic Ridge
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-continuous broad fractured rise,
-top of ridge as much as 3000 m higher than adjacent ocean floor -rift valley |
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Rift Valley
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crack like surface that runs along the axis of the ridge throughout much of its length, long fracture zones
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Abyssal Floor
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-relatively broad and smooth
-abyssal hills cover much of the sea floor -abyssal plains |
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Abyssal Plains
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near continental margins, land derived sediment completely covers abyssal hills
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Seamounts
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-isolated peaks of submarine volcanoes
-some are chains, like Hawaii |
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Trenches
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-lowest areas on Earth’s surface
-invariably adjacent to chains of volcanoes called island arcs -linear |
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Continental Margins
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-continental shelf
-the zone of transition between a continent and an ocean basin -continental slope-more dense -young -not folded like mountain belts |
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Continental shelf
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submerged part of continent
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Continental Slope
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marks the edge of the continental rock mass, found around the margins of every continent and around smaller fragments, longest and highest slopes on Earth
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Heat Exchange
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-Makes the planet dynamic
-Drives from the interior of the earth -Convection moves mass |
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Dynamic
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a system that is composed of individual items or components that work together to make a unified whole, and in this, material and energy move about and change from one form to another
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Conduction
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Heat transfer through a mass
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Convection
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Heat transfer as a result from the movement of a mass
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Radiation
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Heat tranfer from electromagnetic waves from the sun
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Heat Transfer
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-drives hydrologic and tectonic systems
-heat transfers from hotter to cooler regions always |
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Heat Flow
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Flow of heat from the interior of the earth
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4 systems of weather and climate
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evaporation, precipitation, condensation, transpiration
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Atmospheric Circulation
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-Hydrologic systems redistribute water across the earth
-Moisture rises with warm air, air cools water falls |
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Hydrosphere Budget
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-Ocean 97.5% many sources, sinks, evaporation, residence time 3,000 years
-Ice (glacial in Antarctica and Greenland) 2% residence time of 10,000 years -Groundwater .5% occurs almost everywhere in subsurface, residence time 1 month-100’s of thousands of years, depending usually on how deep it is -Lakes residence time: 100-200 years -Rivers residence time: 20 days -Plants remove a lot of water from the ground -Streams, ice, waves, groundwater modifies most of surface of continents |
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Residence time
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average amount of time a tiny bit of water spends in wherever
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Why does the hydrosphere move?
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-Gravity – how does it get to a high location – why not all flowed long since to oceans and stayed there?
-Storms—circulation—heat flow -Heat source (sun) -General circular pattern, water vapor redistribution by atmosphere -currents—driven by wind, upper 300m of ocean |
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Water vapor redistribution by atmosphere
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-warm, moist air rises at equilibrium, drops rain
-depleted in moisture, cools, drops, warms at 30 degrees -evaporates water, moves toward poles -meets cool air at 50 degrees – storms and precipitation |
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Reservoirs
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Ocean, Ice, Groundwater, Lakes, Atmosphere, Rivers, Living Organisms
*These are driven by convective heat transfer |
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Ocean
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-97.5% water
-90% returned by precipitation, 10% runoff -only sink is evaporated -resting time = 3000 years |
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Ice
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-80% not in ocean (2% of total)
-nearly all in Antartica and Greenland -resting time = 10 ka -melt, sea level change 100m |
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Groundwater
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-20% not in ocean (.5% total)
-nearly everywhere on land -soil rest time = 1 month, deep aquifers t=ka to ma |
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Lakes
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-.7% not in ocean, .02% of total
->half in fresh lakes, mostly in Great Lakes, Baikal, East Africa -resting time = 100-200 years for large lakes (long time to flush pollution) |
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Atmosphere
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-.0001% (2mm over surface)
-all air has water (few % to 100%) -resting time = 10 days -it's small, but important, especially storms and distance of water |
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Rivers
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-.0001% at any moment
-resting time = maybe 20 days -small, but important, Transfers water between land and ocean, erosion, transport, etc. -instantaneous volume is small, but carry large volume over time |
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Living Organisms
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transpiration – remove perhaps as much water from ground as rivers
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Effects of Hydrosphere
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-enormous energy involved
-modifies and destroys effects of tectonic system -Finite amount of water -Can locally change water avail (Las Vegas) -Irrigation, builds salt, need to flood fields to flush, depletes aquifer, subsidence, etc -Alter sediment budget, costal erosion, Colorado River |
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Tectonosphere
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-Helps explain why mountain ranges and mid ocean ridges are located where they are
-Temperature is an important factor |
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3 Ways Plates Interact with Each Other
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-Move apart from each other, mainly at mid ocean ridges
-Plates come together -Plates slide past each other |
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Theory of Plate Tectonics
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-Movement can be measured (not a theory)
-Mechanisms that drive motion uncertain (being tested theory) -Plate Tectonics is to geology as DNA is to genetics: unifies, clarifies, explains major features of the earth -Radical change in the view of the earth |
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Features of Plates
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-Continental margin + plate margin not always same
-Some plate have no continental material -Some boundaries uncertain |
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Convergent Boundaries
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plates come together, produces volcanism, types: oceanic crust to oceanic crust, continental crust to oceanic crust, continental crust to continental crust
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Transform Boundaries
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-Boundary between two moving lithospheric plates, usually along an offset segment of the oceanic ridge
ex: San Andreas Fault |
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Divergent Boundaries
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plates pulled apart
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Divergent Margins
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-Spreading, upwelling, form of new crust, hot—low p—high, high heat flow (convection)
-Offset by trans. Faults -New margin – Red Sea vs Atlantic -Lower top and deeper water at lithosphere cools away from the ridge -Motion perpendicular to ridge -Pangaea: super continent that broke up a long time ago -Lithosphere beings to pull apart -Rift valley thins -Crust becomes thin so it produces oceanic lithosphere |
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Convergent Margins
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-Geology complex and varied
-Cool, hi-p plate descends (subduction) (convection) -Subduction not necessarily perpendicular to ridge -Accetionary wedge -Oceanic-oceanic “island arc” -Ocean-continent(with and without magmatism)(with and without mountain belts) -continent-continent (not true sub—underring, thickening, compression) |
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Intraplate Processes
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-Plumes (Hawaii, Yellowstone) (convection)
-Age vs time relation |
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Tectonic Feature of MOR
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divergent margin
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Tectonic Feature of trench
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convergent margin or sub zone
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Tectonic feature of folded mountain belt or volcanic arc
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convergent margin
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Tectonic feature of volcanism
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margins of all types
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Definition of Mineral
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-Naturally occurring
-Inorganic solid (one exception) -Internal structure -chemical composition varies within limits -exhibits physical properties -stability limits – but may be broad or narrow -basic building blocks of rocks |
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Atom
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-comprised of protons and neutrons, surrounded by electrons, distance across atom is about an angstrom (A with circle over it)
-elements unique by number of protons, and variation in electrons and neutrons -if e≠Z, it’s an ion (charged) -the type of bond has a strong influence on mineral property |
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Covalent Bonds
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-share electrons
-these are strong |
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Ionic Bonds
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-occurs when one atom in bond gives up an electron/s and the other one takes it, so they become ions with opposite charges, and opposites attract
-these are weak -tend to come apart in water, soluble in water |
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Most Common Elements
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H, O, Si, Al, Fe, Mg, Ca, K, Na, C
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Why do Mg and Fe substitute?
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Mg^2+ is .72 ang; Fe^2+ is .78 ang.
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Important properites of structure and composition in minerals
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crystal form, cleavage, hardness, density, color, streak, etc.
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Rock Forming Minerals
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-feld, mica, amph, px, ol, qtz, cc, dol, clay, halite, gypsum
-make up almost all of the upper mantle and crust |
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Solid Solution
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-can vary within minutes
-Olivine can have formula between MG2SiO4 and Fe2SiO4 -you can’t think of a crystal as a molecule -for every 19 magnesium atoms, there’s an iron -narrowly defined limits -atoms can substitute for each other based on size and charge -a lot of solid solution substitutes occur for elements on the same column on the periodic table |
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Physical Structure of Diamond and Graphite
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-Diamond, made out of carbon (covalent bonds really strong)
-Graphite, made out of carbon -Diamond and Graphite differ in the way the bonds work |
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Hot Spots
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-melting beneath lithosphere, islands get older and older, Hawaii Island example, Yellowstone
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Plates
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-Plate continental boundaries may be, but need not be, in the same location
-Plate motion differs at boundaries: divergent perpendicular, transform parallel, convergent between |
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Internal structure of Pyroxene
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-There is a unique manner in which the atoms are bonded together, specific geometric pattern
-Example of a mineral that shows unique internal structure |
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Which mineral always has a fixed composition?
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Pyrite (FeS2)
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Cleavage
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how a mineral breaks
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Meta Stable
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rock just waiting to be pushed off a cliff, needs the pushing energy to change
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What is the most abundant mineral in the earth's crust?
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Feldspar
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Magma
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-Molten rock [melt+/-gas+/-crystals] cools to igneous rocks
-Hot, partially molten rock material. Most are a combination of liquid, solid and gas. -Forms igneous rocks when it cools -Intrusive rock – Magma that solidifies below the surface -Extrusive rock – Magma that has reached the surface (becoming lava) without completely cooling and flows out over the landscape. |
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Texture of Magma
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-glassy
-aphanitic -porphyritic-aphanitic -porphyritic -phaneritic -porphyritic-phaneritic -pyroclastic |
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Glassy texture
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Taken from a temperature when crystals would normally form and then cooled rapidly/quenched.)
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Aphanitic texture
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-microscopic crystals [extrusive, cooled quickly, but not too fast, not glassy]
-Relatively rapid cooled -Made of numerous small spherical or ellipsoidal cavities called vesicles. They are created by gas bubbles trapped in the solidifying rock. |
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Examples of rocks with Aphanitic texture
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-Rhyolite – Has the same silicic composition as granite. Not common along ocean ridges or oceanic islands but is more common on the continents
-Andesite – Most abundant lava type after basalt. Occurs mostly along convergent plate margins in island arcs and along continental margins. It is rare in oceanic islands. -Basalt – Most common aphanitic rock. It is abundant on the seafloor -Komatiite – Rare volcanic rock. Found mostly in very ancient rock sequences exposed in the continental shields. |
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Porphyritic-aphanitic texture
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aphanitic rock with phenocrysts [like aph, but erupted magma with x’ls]
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Porphyritic texture
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-2 stages of cooling: Initial stage of slow cooling in which large grains develop Followed by a period of more rapid cooling during which the smaller grains formed
-Phenocrysts – larger, well-formed crystals -Smaller crystals – matrix and the groundmass |
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Phaneritic texture
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-visible crystals [intrusive, cooled slowly]
-Uniform (very slow) rate of cooling and large crystals -Composed of grains large enough to be recognized without a microscope |
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Examples of rocks with phaneritic texture
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-Granite – coarse grained igneous rock composed predominantly of feldspar and quartz
-Diorite – Similar to granite in texture; Plagioclase feldspar is the dominant mineral -Gabbro – Not usually found at the at the earth’s surface. Makes up the lower part of the oceanic crust and is present at some intrusions. Composed of pyroxene, calcium-rich plagioclase, and olivine. -Peridotite – Composed mainly of olivine and pyroxene. Makes up a large portion of the mantle and is not common on the surface. |
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Porphyritic-phaneritic texture
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rock with phenocrysts [intrusive, cooled slowly in two stages]
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Pyroclastic texture
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-ash, crystals, pumice, rock fragments [explosive]
-Produced when explosive eruptions blow crystals and bits of still molten magma into the air as a mixture of hot fragments called ash |
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Examples of rocks with pyroclastic texture
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-Ash – dust sized pieces
-Pumice – vesicular froth glass common among the lager fragments -Tephra – shards of volcanic glass, pumice, broken phenocrysts, and foreign rock fragments -Tuff – the rock resulting from the accumulation of pyroclastic fragments |
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Extrusive Rock Bodies
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-basalt lava flows
-silicic -explosive volcanism |
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Basalt Lava Flows
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-Aa – moves slowly. The hardened crust is broken into a jumbled mass of angular blocks and clinkers.
-Pahoehoe – more fluid than aa flows. “Fossil gas bubbles” make the rock light and porous. -Vesicles – Small holes formed in a volcanic rock by a gas bubble that became trapped as the lava solidified -Fissure eruptions – Instead of issuing from a central vent, basaltic lava is commonly extruded from a series of fractures in the crust (fissures). -Lava lakes – Collapsed caldera (summit craters) that may fill with lava -Lava tubes – Fluid interior breaks through the crust and flows out. -Bombs – large projectiles blown from a volcano -Cinder cone – larger particles that accumulate close to the vent -Shield volcano – Fluid basaltic lava flows freely for some distance, spreading into a thin sheet or tongue before congealing. Shield volcanoes have wide bases. -Columnar joints – flows that cool, contract and may develop a system of polygonal cracks. Similar to mud cracks. -Pillow lava – Extrusion of basaltic lava into water produces a flow composed of a multitude of ellipsoidal masses |
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Silicic
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-Rhyolite domes
-Stratovolcano or composite volcano – a high, step-sided cone centered around the vent formed by alternating layers of tephra and thick, viscous lava flows or domes (Lavas, Tephra, Lahar, Calderas) |
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Explosive Volcanism
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-Like shaking a can of pop – When opened CO2 comes out violently – In a volcano H2O, CO2 and magma come out of solution violently
-Expands and rises in a cloud of ash, pumice, crystals and country rock -Airfall or flow at hundreds of km/hr at hundreds of degrees Celsius -Airfall (ash?) – Smaller particles of ash that form ash cloud? -Welded Tuff – a rock formed from particles of volcanic ash that were hot enough to become fused together -Lateral blast – blast occurring laterally |