EES 1 Midterm 2

What crystalline Igneous texture that (Interlocking mineral grains from solidifying melt) has rapid cooling, crystals do not have time to grow, and extrusive (volcanic)? (you cannot easily make out the individual crystals with naked eye)

Aphanitic

What are gas-rich and silicic - they are EXPLOSIVE, dangerous (& beautiful).

Arc volcanoes (& continental hotspots)

What intrusive igneous setting has Magma injected into a layer gets blocked and cannot spread laterall? The Magma also accumulates into it called a laccolith if convex upward and a lapolith if convex downward?

Blister-shaped intrusions

What is atoms move closer together causing REDUCED volume -more stable at high pressure

Effect of Pressure

What eruptive style produce a vast outpouring of lava: Lava flows stream away from vents. Lava lakes can form near, or inside, the vent. Can produce huge lava fountains 500 m high. Common with mafic magma (basalt)?

Effusive eruption

What conduits for basaltic lava? (A cooled crust forms on top of a basalt flow. A conduit develops in the flow. Tubes prevent cooling, facilitating flow for miles. Lava tubes become caves that can transmit water)

Lava Tube

What can be thin and runny or thick and sticky and what does that style depend on?

Lava flows and it depends on viscosity which depends on Composition, especially silica (SiO2), Fe, and Mg content, Temperature, Gas content, and Crystal content.

Chemical and/or physical rearrangement/alteration of a solid rock under "high" pressure and/or temperature - no melting. No change in bulk chemical composition is required.

Metamorphism

What is this? P increases with depth in the crust. -270 to 300 bars per km (1 bar is almost 1 atm = 14.7 psi). -Metamorphism occurs mostly in 2-12 kbar range. Increase in P packs atoms more tightly together. -Creates denser minerals. -Involves phase changes or neocrystallization.

Metamorphism Due to Pressure (P)

MOR-generated oceanic crust covers 70% of Earth. Basalt erupted from fissures quenches as pillows. Pillow mounds are pulled apart with plate motion.

Mid-ocean ridge volcanism

Magma which cools slowly underground and form large crystals has a ____ texture.

Phaneritic

What crystalline Igneous texture that (Interlocking mineral grains from solidifying melt) that has slow cooling, crystals have a long time to grow, and intrusive? (you can see all the crystals)

Phaneritic (coarse-grained)

Arc volcanoes result from what?

adding water to hot rock

The melting assoiated with the addition of carbon dioxide (CO2) or water (H2O) to rocks is referred to as what?

addition of volatiles

What are the four types of sedimentary?

biochemical or biogenic - biologically-mediated mineralization. organic - dead body tissues. chemical - evaporites, spring deposits.

This is what

convergent plate boundary

The direction of the ____ tell us a lot about the paleo-flow direction

cross beds

What process is responsible for separating Earth into parts of different composition?

differeniation

Magma intrusions which are often vertical and cuts across layers is called a _____.

dike

What depends on viscosity of melt in extrusive igneous settings? (Lava flows cool as blankets that often stack vertically. Lava flows exit volcanic vents and spread outward: Low-viscosity lava (basalt) can flow long distances and High-viscosity lava piles into mounds of angular blocks)

eruption style

What ejects huge clouds of ash and debris that rise several kilometers into the sky? (Lapilli are hail-sized debris that falls near the volcano. Ash is finer, dust-sized debris that travels great distance from the volcano. A pyroclastic flow is an ash and debris avalanche.)

explosive eruption

A magma high in silica (SiO2) is called what?

felsic

What is preferred orientation of planar (flat) minerals within a rock. A distinctive feature of meta-morphic rocks!

foliation

What is the mountain-building - either a process or a particular event. Related to subduction and/or collisions.

orogeny

What is the reaction of rock minerals with oxygen, thus changing the mineral composition of the rock. When minerals in rock oxidize, they become less resistant to weathering. Iron, a commonly known mineral, becomes red or rust colored when oxidized.

oxidation

What is the break up rock into transprtable chunks equals clasts and/ or the reaction that transform minerals to ones stable at Earth surface(hydrolysis, oxdiation, carbonation)?

physical and chemical weathering

Arc volcanoes are dangerous because they typically:

generate pyroclastic flows. erupt explosively. have high magma gas content.

Avalanches of dense, hot ash and gas that rush down the sides of a volcano during an eruption are called

pyroclastic flows

What is Igneous Rock mainly used as? Why?

is used extensively as building stone. Ex. Office buildings, Kitchens, etc. Why? It's Durable (hard), Beautiful, etc. Often called "granite"; it is not always true granite. Identify by Color (light or dark) or Texture

What depends on Silica content (Lower SiO2 content = lower of it), Temperature(Hotter T = lower of it), and Volatile content (Higher volatile content = lower of it)?

magma viscosity

How do we define the level of weathering as a function of time and transport distance?

maturity

What can cut across bedding planes (one good indicator of metamorphic conditions!)?

metamorphic cleavage

What is this? Heat energy breaks and reforms atomic bonds. Sources of heat: The geothermal gradient. Magmatic intrusions. Compression. The depth to metamorphic T varies with tectonic setting.

metamorphism due to heat

What does it mean when planning, evacuation-moving those at high risk saves lives, diverting flows-flowing lava can be diverted?

mitigating volcanic hazards

Which rock contains most of our record of earth history, especially history of LIFE, can tell what Earth environment looked like from the rocks, and contains all of our fossil fuel?

sedimentary

What are rock had characterized by composition has Siliceous: quartz-rich (70% to 85%), Argillaceous: clay-rich, and Carbonate: contain calcite or dolomite?

sedimentary rock

What cause shape changes &preferred orientation formineral growth

stresses

What is affected by volatile and viscosity of the magma?

the explosivity of the valcano

What are the five steps into making (clastic) sedimentary rock?

weathering - breaks down existing rock. erosion (= start transportation). transportation. deposition (= end transporation). lithification = turning loose sediment into sedimentary ROCK.

Dormant arc volcano has its plumbing blocked up from prior activity - like cork in a bottle. New magma ponding underneath can't de-gas. Pressure builds. Pressure builds enough to force an exit & becomes a runaway process. Gas release becomes an explosion w/ magma fragments mixed with gas. Explosion fractures up the volcano. As a result, for a while, gas release is easy. Magma self-seals the volcano & primes it for another explosive eruption. What is this?

A simple (or simplistic) Eruption Model

Most Common Rock Type in Arc Volcanoes. Has a relatively high content of silica (SiO2). This makes the magma very viscous. Viscous lavas can pile up to make cones. Also viscous lavas don't release gas bubbles easily.

Andesite

Higher SiO2 content makes it viscous. (Unlike basalt, they do not flow rapidly. Instead, they mound around the vent and flow slowly.) The crust fractures into rubble, called blocky lava. The flows remain close to the vent.

Andesitic Lava Flows

What type(s) of lava is associated with most explosive volcanoes?

Andesitic and Rhyolitic

What is fine crystals and bits of glass that can rain down and become cemented to form tuff (a solid, porous rock)?

Ash

What is a Hawaiian word describing basalt that solidifies with a jagged, sharp, angular texture and forms when hot, flowing basalt cools and thickens and with flow, lava crumbles into shards and fragments?

A′a′

What lava flow is often thin and fluid that can flow rapidly (up to 30 km per hour) for long distances (up to several hundred km)? (Most flows measure less than 10 km. Long-distance flow facilitated by lava tubes.)

Basalt flow

Which type of lava generally creates effusive, gentle eruptions?

Basaltic

What is a group of plutons that is several hundred kilometers long and over 100 km wide? he Sierra Nevada range is an exposed one of this?

Batholith

Up through a continental plate. Yellowstone—eruption ~640 Ka created a 100 km caldera. (A thousand times more powerful than Mt. St. Helens. Deposited vast ignimbrite deposits in three gigantic eruptions. Magma beneath the caldera continues to fuel geysers.)

Continental hot spot volcanism

Many volcano types reflecting: Partial melting of the mantle (mafic magmas). Partial melting of the crust (felsic magmas). Examples: East African Rift Basin and Range Province Midcontinent Rift

Continental rifts volcanism

Most volcanoes form here. Volatiles from subducting plate initiate melting. Arc volcanoes develop on the overriding plate. The Ring of Fire dominates Pacific margins.

Convergent boundaries volcanism

Foliated verse Non-foliated

Degree of foliation: Slate. Phyllite. Schist. Gneiss (migmatite). Flattened-clast conglomerate. Mineralogy: Hornfels. Amphibolite. Quartzite. Marble. Ecologite.

What are the ways to predict volcanoes?

Earthquake activity. Volcano "inflation". Increased heat flow. Increased gas emission. Statistical behavior/history of each volcano may give long-term pattern. PROBLEM: Volcano uniqueness & long-term repose times . Cannot predict exact times and styles of eruption.

Lava flows—lava threats are mostly from basaltic lava. Threat of pyroclastic flows—superheated ash clouds Threat of falling ash and lapilli Lahar - volcanic mudflow: Fast moving down sides of volcanoes. Triggered by rain or melting of ice/snow mixing with ash. Blast—rarely, explosions are ejected sideways. Landslides—eruption-related slope failures Earthquakes—moving magma causes earthquakes. Tsunamis—island arc eruptions can create giant waves.

Eruptive/volacno Hazards

What eruptive style release pressure catastrophicall: High gas pressure is from more viscous SiO2-rich magma. Create pyroclastic flows and cover the land with tephra. Mostly andesitic and rhyolitic compositions.

Explosive eruption

Other Volcanos have an explosive eruption, where the lava explodes out with tremendous force

Felsic lavas

Voluminous lava eruption above a plume. When a mantle plume intersects base of rifting lithosphere. Lava spreads over large areas; great thicknesses stack up. Creates a large igneous province (LIP) (i.e., Columbia River Plateau).

Flood basalts volcanism

What is a chemical reaction caused by water. Water changes the chemical composition and size of minerals in rock, making them less resistant to weathering?

Hydrolysis

Why does magma rise?

It is less dense than surrounding rocks. Buoyancy forces act to drive magma upward. The weight of overlying rock creates pressure. Squeezes magma upward

What is unusually large outpourings of magma: -Mostly mafic, include some felsic examples. -Mantle plume first reaches the base of the lithosphere. -Erupts huge volumes of mafic magma as flood basalts with Low viscosity, Can flow tens to hundreds of kilometers, and Accumulate in thick piles.?

Large Igneous Provinces (LIPs)

What lava flow is very hot, low silica and low viscosity?

Mafic lava

Some volcanos have a gentle eruption, where the lava mostly just spills out and flows away

Mafic lavas

A plume under an oceanic plate. Decompressional melting creates large volumes of basalt. Building above sea level, basalt can flow long distances. Lava builds upward and outward and the island grows. Submarine slumps remove large masses of the volcano.

Oceanic hot spot volcanism

What are comparatively gentle - produce lots of lava, but few huge explosions.

Oceanic hotspot volcanoes & mid-ocean ridges

What is a Hawaiian word describing basalt with a glassy, ropy texture and forms when extremely hot basalt forms a skin and with flow, the skin is rolled into ropy ridges and furrows?

Pahoehoe

What is round blobs of basalt cooled in water? Underwater, basalt cools instantly, forming a pillow. (The pillow surface is cracked, quenched glass. Lava pressure ruptures a pillow to form the next blob. The process repeats to form a mound of pillow basalts.) Common on the mid-ocean ridge.

Pillow Basalt

What eruptive style has huge explosive eruptions Eject huge quantities of material: Often destroy parts of the stratovolcano they come from. Examples: Mt. St. Helens, Mt. Vesuvius, Mt. Pinatubo?

Plinian eruption

What are blob-shaped intrusions that range in size from tens of meters to tens of kilometers? May start as diapirs (buoyant, light-bulb-shaped magma) and some may assimilate wall rock in a process called stoping. Form from several superimposed dikes and/or sills that coalesce into a single, massive body. Continued uplift and erosion exposes it.

Plutons

What crystalline Igneous texture that (Interlocking mineral grains from solidifying melt) has a mixture of coarse and fine crystals, two-stage cooling history: Initial slow cooling creates large phenocrysts and Subsequent eruption cools remaining magma more rapidly? (combination of big and small crystals)

Porphyritic texture

It is refers to volcanic rocks which were formed by the eruption event. This texture is often composed of the "debris" from the eruption. Pre-existing rocks that were shattered by eruption. After fragmentation, the pieces fall and are cemented together. Also called volcanic breccia. During certain types of eruptions, bits of lava cool in the air and rain down. This material is called tephra. Tephra is defined by size (The largest size are called blocks, and can be HUGE. Bombs are a bit smaller, and can be further classified by shape. Lapilli are smaller still, and can be thought of as "little stones". Ash is the smallest size, defined to have a particle size smaller than 2 mm, though it can be much smaller)

Pyroclastic texture

What has the highest SiO2; is the most viscous lava that rarely flows but plugs the vent as a lava dome. Sometimes, lava domes are blown to smithereens.

Rhyolitic Lava Flows

Broad, slightly dome-shaped (like an inverted shield) Constructed by lateral flow of low-viscosity basaltic lava Have a low slope and cover large geographic areas Mauna Loa on Hawaii is a perfect example.

Shield volcanoes

atoms move through a solid crystal

Solid state diffusion

This may contract, creating vertical fractures that are hexagonal in cross-section. This feature, columnar jointing, indicates former lava.

Solidified flows

Large, cone-shaped volcanoes with steeper slopes. Made of alternating layers of lava, tephra, and debris. Often symmetric; can be odd shapes from landslides, etc. Examples include Mt. Fuji, Mt. Rainier, Mt. Vesuvius.

Stratovolcanoes (composite volcanoes)

What eruptive style regular "burps" of magma: Stromboli has been erupting throughout recorded history. Every 10 to 20 minutes it shoots out lapilli and blocks. These trace arcs in the sky at night. Stromboli is an example of a basaltic pyroclastic eruption?

Strombolian eruption

What eruptive style has some past eruptions have been huge: The geologic past has many examples. Yellowstone National Park has a caldera 72 km across. Erupted 600 cubic miles 2 million years ago (2 Ma). Mt. St. Helens erupted 0.26 cubic miles in 1980?

Supervolcanoes

What eruptive style vent erupts in shallow seawater: Creates a large amount of steam. Ash is carried out of the water by the steam?

Surtseyan eruption

What are the categorized intrusive igneous setting shapes?

Tabular (sheet)-shaped. Blister-shaped. Balloon-shaped.

What has roughly planar with a uniform thickness, Vary in size (Centimeters to hundreds of meters thick), and Two types: A dike cuts across pre-existing layers or A sill is injected parallel to the rock layers

Tabular intrustions

What is the causes of metamorphism

Temperature. Pressure - driven by volume considerations. Stress. Hot fluids (hydrothermal alteration). contact - igneous intrusion locally heats burial. (dynamic or cataclastic - occurs in fault zones). (dynamothermal) - regional tectonics. hydrothermal - hot water. shock or impact - meteorite impact.

What causes volcanoes to explode?

The gas

How to identify the textures of igneous rocks?

The size, shape, and arrangement of the minerals. Interlocking (mineral crystals fit like jigsaw-puzzle pieces.), Fragmental (pieces of pre-existing rocks, often shattered), Glassy (made of solid glass or glass shards). It directly reflects magma and cooling history.

Magma moves which direction?

Upward in the crust and once it reaches surface, it erupts as lava from a volcano.

Which type of plate boundary is NOT associated with volcanism?

Transform

Why is Felsic Lava generally the most viscous lava?

Very high Silica content, Often (but not always) lower temp than mafic lava, and Generally low volatile content Mafic lava is opposite these points, and has low viscosity

What igneous texture has sometimes a large amount of gas can become trapped in the lava as it cools that creates a rock with a HUGE number of small holes causing it to become light weight (low denisty so float in water)?

Vesicular texture

What governed the speed of magma flow? It measures resistance to flow. Lower flows easily (warm honey) vs. Higher does not flow easily (cold honey).

Viscosity

What is it called when sometimes deep (mantle) magma rushes to the surface at supersonic speed through a crack in the crust. When it comes up, it can rip apart wall rock. It is like a neck, but has a deeper source, and may include volcanic breccia.

Volcanic Pipe

What is it called when lava comes to the surface through vents. The central vent of a volcano can become plugged with hardened lava. can be stronger than the surrounding rocks. Over time, the volcano may erode away, leaving behind only its neck.

Volcanic neck

Pyroclastic debris—lava fragments that freeze in air. Preexisting rock—blasted apart by eruption. Landslide debris—blocks that have rolled downslope. Lahars—transported as water-rich slurries.

Volcaniclastic deposits

A mountain built extrusive igneous activity. Active, dormant, or extinct.

Volcano

What eruptive style moderately sized and explosive: Emit pyroclastic eruptions. Named for the island of Vulcano?

Vulcanian eruption

What is the process of rock minerals reacting with carbonic acid. Carbonic acid is formed when water combines with carbon dioxide. Carbonic acid dissolves or breaks down minerals in the rock. This is very common in calcitic rocks (limestone) and causes dissolution, which may leave behind holes and caves?

carbonation

Conical piles of tephra (Rhyolitic). The smallest type of volcano. Built of ejected lapilli-sized fragments piled up at a vent. Slopes are at the angle of repose. Often symmetrical with a deep summit crater.

cinder cone

What can make volcanic eruptions alter?

climate. Ash and aerosols high in the atmosphere block sunlight. This causes atmospheric cooling.

What is the benefits of Igneous Activity?

geothermal energy. mineral deposits. rich volcanic soils. our atmosphere. deep sea hot springs where life evolved. mountains to climb & ocean islands.

What igneous texture is when the lava cools so quickly that the molecules do not have the time to arrange themselves into a crystal? (will exhibit conchoidial fracture. The broken edges can be VERY sharp)

glassy texture

What helps break/separte the colecules as they move around?

volatiles