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Description
Flashcards by abby Radske, updated more than 1 year ago
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Created by abby Radske
almost 7 years ago
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| Question | Answer |
| Factors that determine the "violence" of eruptions | high viscosity = explosive eruption (bubbles cant continuously escape, builds up) 1) composition : high silica = high viscosity 2) temp : low temp = high viscosity 3) gasses in magma : low [gas] = high viscosity |
| Materials Extruded from a Volcano | Felsic materials : silica rich, high viscosity (continental rock) Mafic (basalt) : silica poor, low viscosity (mantle) |
| How does magma get silica rich if it comes from the mantle? | the mantle is mainly mafic, but when the mantle rock melt reaches the crust (felsic, high silica), it melts the crust as well, which makes the melt more felsic. ** rarely ever felsic in oceans ** |
| Pahoehoe Lava (EFFUSIVE) twisted, ropey structure | |
| Aa Lava (EFFUSIVE) rough, jagged, blocky | |
| Pillow Lava (EFFUSIVE) found underwater | |
| Lava Dome (EFFUSIVE) bulbous mass of congealed lava low [gas], so it seems like it should be explosive, but isn't | |
| Pyroclastic Materials | Tephra: fine dust fragments Cinders: pea sized fragments Pumice: rock with lots of pores (frothy lava) Lapilli: walnut sized fragments Blocks: hardened/cooled lava Bombs: Ejected as hot lava, then cools when in air, makes teardrop shape |
| Eruption Columns | made up of a cloud of tephra heavier material falls back to earth can cause volcanic winter |
| Lateral Blast | side of the volcano blows out instead of top. earthquakes can cause the eruptions that occur to be lateral; if the volcano breaks apart on the side, it will be easier for the lava to eject on the side. |
| Pyroclastic Flow & Surges | mix of hot gas and rock flows like an avalanche, moves fast usually in valleys due to column/dome collapse |
| Eruption Types: Hawaiian | low viscosity non explosive little/no pyroclastic material |
| Eruption Types: Strombolian | Blasts of lava includes bombs & tephra low elevation columns & pyroclastic flows mildly explosive |
| Eruption Types: Vulcanian | sustained explosions of super viscous lava columns reach many km high, then collapse to pyroclastic flows very explosive |
| Eruption Types: Pelean | collapse of lava domes violently explosive |
| Eruption Types: Piinian | sustained ejection of magma eruption column 45 km high huge ash clouds violently explosive |
| Eruption Types: Phreatic | magma mixes with shallow groundwater; flashes to steam explosively erupts no new magma reaches the surface in this eruption |
| Volcanic Landforms: Volcanic cone | the hill/mountain |
| Volcanic Landforms: Vent | surface source of eruption (where it actually erupts) |
| Volcanic Landforms: Crater/Caldera | the depression that surrounds the vent caldera = large crater = small |
| Volcanic Landforms: Fissures | cracks in the ground that ooze the lava usually low viscosity lava (basalt) |
| Volcanic Landforms: Volcanic Pipes & Necks | short conduits that connect the magma chamber to the surface |
| Volcanic Landforms: Lava Tube | hot underneath, crystallizes on top |
| Shield Volcano created from effusive eruptions near main vent, grows slowly over time little pyroclastic materials composition: mafic Viscosity: low | |
| Stratovolcano most common created from many layers that get covered by lava over and over again most violent eruptions | |
| Cinder Cone usually less than 1 km base tephra and loose pyroclastic material | |
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Images (binary/octet-stream)
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Volcanic Domes bulbous mass of congealed lava most associated with explosive eruptions of gas-poor magma |
| Fumaroles | a vent where gases emerge at the surface of the earth CO2, SO2, H2O |
| Hot/Thermal Springs | cold water at surface sinks into the permeable volcanic rock, stops at the impermeable rock, then moves along until reaches a magma body, heats up, then comes to surface gently rises to the surface |
| Geyser | if the water builds up pressure when coming up to the surface, or flow gets restricted, makes a geyser |
| Volcanic Eruptions : Secondary Effects Lahar | tephra & water; can happen right after eruption or years later |
| Volcanic Eruptions : Secondary Effects Debris Avalanches/flows | unconsolidated volcanic material that flows down slope due to gravitational instability |
| Volcanic Eruptions : Secondary Effects Tsunami | results from flows, avalanches, landslides, and caldera collapses entering body of water |
| Volcanic Eruptions : Secondary Effects Atmospheric Effects | both solid and gas particles are released during eruptions CO2: can raise temp by a few degrees for long periods of time SO2: can cause acid rain Dust: can cover the sun - lower temp |
| Volcanic Eruptions : Secondary Effects Positive Effects | geothermal energy metallic ore deposits fertile soil = food&drink most of historical atmospheric composition contributed by volcanoes sending gas into the air |
| Volcanic Monitoring: Short term Seismic Monitoring | earthquakes usually come before a volcanic eruption Volcanic tremor: continuous rhythmic shaking |
| Volcanic Monitoring: Short term P&S waves | S waves cant go through liquids, so if sent through one side, and not shown on other, then magma body full of magma |
| Volcanic Monitoring: Short term Ground Deformation | due to the inflation of the magma chamber when magma flows in Tilt Meters: use meters to measure angle of ground, track angle changes |
| Volcanic Monitoring: Short term change in magnetic field | many rocks have minerals that are magnetic when temp rises to certain level, minerals can stop being magnetic |
| Volcanic Monitoring: Short term changes in gas composition | gas coming out of a volcano changes before an eruption increase of HCl & SO2 |
| Volcanic Monitoring: Short term electrical resistivity | all other changes cause a change in electrical resistivity when magma moves in, resistivity decreases |
| Volcanic Monitoring: Short term Ground water changes | when magma enters, changes in the ground water system can happen can make the water rise or fall |
| Volcanic Monitoring: Short term heat flow | when magma comes close to the surface, the temp of the surface/ground water will increase |
| Volcanic Monitoring: Long term | mostly the knowledge of the geologic and eruption history of the area long term more easy to monitor eg. mapping bedrocks |
| Divergent Margins | plates moving apart can happen in ocean or continent always leads to the creation of an ocean basin crust is stretched and thinned |
| Transform Boundaries | slide along one another no igneous activity plates are conserved |
| Convergent Boundaries | plates moving toward each other gravity is driving force; old tectonic plates sink and get recycled at the mantle crustal thickening, igneous activity. nature depends on types of plates involved |
| Ocean-ocean Convergence | marked by deep ocean trench & volcanic island arc has subduction zone |
| Ocean-continental Convergence | Marked by ocean trench, volcanic arc & mountain belt, has subduction zone thermal heating & lots of igneous activity & some crustal shortening |
| Continental-continental Convergence | marked by mountain belts and thrust faults extreme thermal heating, some igneous, lots of crustal shortening |
| Faults | Fractures in bedrock where there was movement loss of cohesion of a body when its under the influence of stress Considered active if movement happened in last 15 000 years |
| Hanging Wall | happens above a fault plane |
| Footwall | occurs below fault plane |
| Normal fault | Hanging wall moves down in respect to the foot wall results in thinning of crust |
| Transform Fault (Strike-slip) | Displacement is horizontal hanging wall and foot wall slide past each other |
| Reverse/thrust Faults | Hanging wall moves up with respect to foot wall results in compressional forces & thickening of crust |
| Joints | Fractures/cracks in bedrock where essentially no movement has occurred |
| Dome | an upward displacement of rocks |
| Basin | a downward displacement of rocks |
| What Produces an Earthquake? | when rock bodies past one another, the rocks bend and store elastic energy (a build up of strain) when the frictional resistance holding the rocks is overcome, causes earthquake |
| What is Seismology? | the study of earthquake waves |
| Types of Seismic waves: S waves | perpendicular to direction of movement, cant pass through liquids |
| Types of Seismic waves: P waves | parallel to direction of movement |
| Types of Seismic waves: Surface waves | due to long periods of amplitude of motions. travels along outer part of earth |
| Types of Seismic waves: Rayleigh (R) waves | moves like an ocean wave the most destructive |
| Types of Seismic waves: Love (L) waves | moves side to side |
| How do you Locate the Epicentre? | ?? |
| Intensity | the measure of the amount of shaking at a given location based on amount of damage |
| Magnitude | Estimates the amount of energy released at the source of the earthquake |
| Types of Magnitude Scales: Richter scale | based on the size of the S wave on seismic gram (less than 2.0 not felt, I unit inc. = 10x wave, 33x energy) |
| Types of Magnitude Scales: Moment-magnitude Scale | gauges the earthquakes total energy (Total length rupture X depth of rupture X total amount of slip along rupture X strength of rock) |
| What contributes to the amount of damage of an earthquake? | the intensity & duration of the vibrations the type of material above the ground the design of the structures |
| What kind of destruction usually occurs from an earthquake? | Liquefaction : disconnected materials saturated with water changes into a mobile fluid (NO water added!) Seiches : uniform sloshing of water in water systems, can weaken walls of containers, cause destruction |
| Rock Behaviours | Elastic : deformed material return to original shape afterwards, has a limit Plastic : permanent deformity, this also has a limit Rupture/Brittle : material will rupture |
| Earthquake Predictions : Long Term | Seismic gaps : an active fault that has been "quiet" for some time Strain monitors & ground deformations |
| Earthquake Predictions : Short Term | small foreshocks occur beforehand a bulge in the crust/land the seismic wave velocity will decrease changes in gases & groundwater |
| Composition of Ore Minerals | most ore minerals are found as sulphides some others are found as oxides very rare amount occur alone |
| Cause/affect of Acid Mine Drainage | when the sulphides are mined, the left over materials (gangue) that contain sulphur will become oxidized, when this happens, an acidic environment will be created. This can damage many ecosystems, and create many environmental issues. |
| Hydrothermal Mineral Deposits | concentration by hot water flowing through fractures/pores in rocks Veins, Disseminated, VMS, Sediment associated |
| Magmatic Mineral Deposits | Concentration by magmatic processes in a body of igneous rock Fractional crystallization, Immiscibility, Pegmatites |
| Sedimentary Mineral Deposits | Concentration by precipitation for sea water Banded Iron formations |
| Placers | Concentration by weathering processes eg. gold |
| Deposits Associated with Weathering | Concentration by weathering processes Supergene, Residual Enrichment |
| Fractional Crystallization | a magmatic ore deposit heavy minerals will crystallize early, then settle and concentrate at the bottom of the magma chamber |
| Immiscibility | Magmatic Ore deposit the sulphides will separate from the magma before it crystallizes (still liquid), then it will settle at the bottom of magma chamber because more dense liquid |
| Pegmatites | Magmatic Ore Deposit the crystallization occurs in the shallow crust, where there are large fractures. because of the large fractures, the crystals that form are large, and course grained. the metals will transport down |
| Deposit Associated with Metamorphism (Skarns) | a closed system the igneous body will change its surrounding bodies, as well as the surrounding bodies will change the igneous body |
| Veins | Hydrothermal Ore Deposit originates from igneous bodies; hot water will flow along fractures, cool, then precipitate the metallic ions to produce vein deposits (usually in areas with lots of faults) |
| Disseminated | Hydrothermal Ore Deposits associated with igneous activity; Metals are distributed throughout the rock body, instead of concentrated in veins. you need a large volume of rock to get a profitable amount of ore. usually found in volcano (copper) |
| VMS (Volcanogenic Massive Sulphides) | Hydrothermal Ore Deposit where massive sulphide deposits are found; black smokers will release metal particulate matter, which will undergo a change in pressure, pH, etc when coming out and reacting with water. causes sulphides to precipitate to ocean floor |
| Associated with sediments : SEDEX (Sedimentary Exhalative Deposits) | Hydrothermal Ore Deposit fractures along the sea floor allow fluids to come up, which creates sulphides. |
| Associated with sediments : Unconformity-Associated Uranium | Hydrothermal Ore Deposits in sediments, uranium containing fluids will become oxidized, then reduced again. this changes the chemical aspects, causing the precipitation of uranium metals |
| Associated with sediments : Mississippi Valley-type Deposits | Hydrothermal Ore Deposit oxidized metal-bearing salt waters that migrate toward a basin edge and fill cavities in limestone |
| Banded Iron Formations | Sedimentary Ore Deposits formed in reducing conditions, during early history of earth, dissolved iron would accumulate in ocean basins and would crystallize |
| Placer Deposits | formed when heavy metals are mechanically concentrated by currents in rivers & gravity EG. gold is sourced in pure form crystallized somewhere else, then transferred in a stream and gets stuck & accumulates |
| Supergene | Associated with Weathering soluble minerals are dissolved near the surface, then are brought somewhere deeper, where it is re-precipitated near water table (semi precious) |
| Residual Enrichment | concentrates metals into economically valuable concentrations Laterite: forms by deep weathering of parent rock and leaching out elements like silica |
| Diamonds | found in the ultramafic rocks "kimberlites" kimberlite magma originates in great depth, and rises quickly to surface, picking up diamonds in upper mantle |
| Kimberlite Pipes | like the neck of a volcano, melts deep into lithosphere, then erupts picks up diamonds in upper mantle |
| Coal | formed from decay and compression of land plants organic matter is accumulated in swamps (anoxic environments) where there is little O2 & rapid sedimentation |
| Oil & gas | derived from marine plants and animals remains under anoxic conditions burial over millions of years produces hydrocarbons |
| Tar & Oil Sands | viscous, cannot be simply pumped out Alberta has major resources: 20% can be mined, the rest has to be heated and pumped due to being too deep |
| Oil & Shale Gas | use "fracking" to get it out has less environmental impacts that coal power plants, lower greenhouse gas emissions, and high economic value can cause water contamination, leaks methane to atmosphere, could cause earthquakes |
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