Earth Mat Flashcards - Ch 9

1
Q

Lava commonly erupts from a _________ located in a crater near the summit of the volcano.

A

central vent

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2
Q

Low discharge flank eruptions produce smaller _________ along the summit, side or base of larger volcanoes.

A

parasitic volcanoes

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3
Q

Mauna Kea has _____ parasitic cones

A

100

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4
Q

are large, generally circular to oval depressions caused by subsidence of Earth’s surface. in the context of volcanism

A

Calderas

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5
Q

Magma Loss in caldera formation can be caused by two things

A

subsurface withdrawal of magma from a shallow chamber as magma migrates to another location,
cataclysmic eruptions that empty the shallow magma chamber.

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6
Q

is an intrusive igneous body that is circular, oval or arcuate in plan view and has steep contact

A

A ring dike or ring dyke

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7
Q

, are the product of massive outpourings of low viscosity basaltic lava that envelop hundreds of thousands of square kilometers.

A

Flood basalts , also known as large igneous provinces (LIP)

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8
Q

Mantle Hotspot related LIP

A

Ontong Plateau, W. Pacific
Kerguelen Plateau, Indian Ocean

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9
Q

Continental Flood Plateau

A

Deccan Traps, India
Siberian Flood Basalts
Karoo, E. Africa
Columbia River/Snake River Plain, N. America

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10
Q

Marine and continental
Records break up of pangea

A

Central Atlantic Magmatic Province (CAMP)

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11
Q

consist of a 65,000 km long global network of submarine rift mountains

A

Ocean ridges

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12
Q

Rare examples of surface exposed ocean ridges

A

Iceland, Galapagos Is., Azores Is.

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13
Q

As hot (1100 – 1300 ° C) basaltic magma rises upward and reacts with cold seawater, spheroidal ____________ develop

A

pillow lavas

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14
Q

Ocean ridges also contain _________ that emit lower temperature (100 – 300 ° C) solutions that precipitate light - colored minerals such as calcite, gypsum, barite and quartz.

A

white smokers

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15
Q

are broad, sloping edifices that cover hundreds to thousands of square kilometers with shapes that resemble the defensive shields of ancient warriors.

A

Shield volcanoes

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16
Q

5 Shield volcanoes of the Big Island of Hawaii

A

Kilauea
Mauna Loa
Mauna Kea
Hualalai
Kohala

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17
Q

The Hawaiian eruptions that produce shield volcanoes also generate fiery basaltic___________ several hundred feet high

A

lava fountains

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18
Q

Airborne blobs of liquid lava emitted by fountains are referred to as

A

spatter

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19
Q

Spatter that solidifies at the base of the lava fountains is referred to as

A

welded spatter or agglutinate deposits

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20
Q

Lava fountains that erupt via fissures produce linear ridges called ____________ on either side of the fissure

A

spatter ramparts

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21
Q

are elevated lateral banks that contain the lava flow within stream-like channel.

A

Lava levees

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22
Q

are shallow subterranean tunnels channelling lava beneath thin, solidifi ed basaltic roofs.

A

Lava tubes

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23
Q

lava consists of low viscosity, “ runny ” basaltic lava which produces thin flows with a billowing, rippled and/or ropey surface

A

Pahoehoe lava

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24
Q

More viscous aa lava tends to produce thicker, slower moving lava flows with angular, jagged, fractured surfaces

A

Aa lava

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25
Q

are steep - sided (~30 – 35° ) conical features composed of tephra.

A

Pyroclastic cones

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26
Q

Tephra consists

A

of volcanic rock fragments of various sizes and compositions emitted during explosive eruptions.

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27
Q

Pyroclastic cones composed predominantly of vesicular basaltic material.

A

Scoria cones

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28
Q

Pyroclastic cones consisting of ash, lapilli and bomb - sized particles of various compositions that accumulate as circular to oval - shaped conical volcanoes

A

Cinder cones

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29
Q

are majestic cone - shaped mountains encompassing tens to hundreds of square kilometers in area with slopes ranging from 10 ° to 30°

A

Composite volcanoes

30
Q

consists of smooth - sided blocks up to several meters in diameter that tumble downslope
lithifies as volcanic breccia deposits

A

Block lava

31
Q

develop when a solidified magma plug is pushed up through the conduit, forming a vertical column on Earth ’ s surface.

A

Spines

32
Q

are steep - sided, blister - like forms that occur within volcanic craters

A

Domes

33
Q

Explosive volcanic eruptions produce a vertical plume or eruption column that can be divided into three distinct parts

A

lower gas thrust
Upper convectice thrust
Umbrella Region

34
Q

region in the eruption column where
material thrust from the vent
100 to 600 m/s

A

Lower Gas Thrust

35
Q

region in the eruption column where
convective rise of heated atmospheric gases and fragments

A

Upper convective thrust region

36
Q

region in the eruption column where
vertrical plume begins to spread laterally as the result of temperature inversions

A

Umbrella region

37
Q

Two modes of eruptive column behavior ______________ result in two kinds of deposits: pyroclastic fall (air fall) deposits and pyroclastic fl ow deposits.

A

– convective thrust and gravitational collapse–

38
Q

occurs when the thrust region plume exhibits buoyancy

A

Convective thrust

39
Q

_of the plume occurs due to negative buoyancy
initiation of pyroclastic flows

A

Gravitational collapse

40
Q

deposits are produced by airborne pyroclasts propelled upward in an eruption column

A

Pyroclastic fall (air fall)

41
Q

lateral sequence of air fall particales from nearest to farthest

A

Bombs and breccia settle first and closest, smaller particles slow and farthest
Solidifies deposits grades upward from brccias to lapili tufts and lastly fiend tuffs
Distal ash - sized particles are deposited and later compacted and cemented together as ash fall tuffs

42
Q

deposits generally lack stratification and are poorly sorted
chaotic mixtures of clast sizes are deposited rapidly.

A

pyroclastic flow

43
Q

Three major types of pyroclastic flows are recognized:

A

Pyroclastic Surges
Pumice Flows
Nuee Ardentes

44
Q

Pyroclastic flow
very low density, extremely hot, gaseous flows
ash - to lapilli - size particles; 100 km/h
Low densities allow surges to defy gravity and climb upwards

A

Pyroclastic surges

45
Q

Pyroclastic flow
low to moderate density, hot vesiculated flows
Siliceous pumice flows produce light - colored, vesicular ignimbrites
Andesitic to basaltic flows produce vesicular scoria flow.

A

Pumice flows

46
Q

Pyroclastic flow
fluidized mixtures of hot, incandescent rock fragments and gases
1000C at 150 km/h
High density, vesicle - poor block and ash pyroclastic flow deposits are generated

A

Nuées ardentes (French for “ fiery clouds ”)

47
Q

Siliceous pumice flows produce light - colored, vesicular _________

A

ignimbrites

48
Q

are volcanic mudflows up to tens of meters thick with the consistency of wet cement.

A

Lahars

49
Q

Lahars can form at three different times:

A

Synchronous with volcanism (syn-eruption lahars) and active pyroclastic flow.
After volcanism has ceased (early post - eruption lahars)
slopes of dormant or inactive volcanoes (late post - eruption lahars)

50
Q

The 1991 Mt Pinatubo (Philippines) eruption involved both ________ and _______ lahars

A

syn-eruption and post -eruption

51
Q

are large volcanic features that lack the typical, highly elevated landform associated with most volcanoes.

A

Rhyolite caldera complexes

52
Q

Rhyolite calderas are known as __________; since low depression calderas are the signature aspect,

A

inverse volcanoes

53
Q

After eruption of rhyolite calderas, they can emit smaller scale eruptions over long time intervals and experience regional uplift, referred to as

A

“resurgence”

54
Q

eruption involving both magma and heated groundwater
magma below water table

A

Phreatomagmatic eruptions

55
Q

Volcanic features produced by phreatomagmatic eruptions include

A

tuff rings, tuff cones (both positive) and maars (negative).

56
Q

gently sloping, circular structures composed of stratified, glassy volcanic debris and scoria
explosive eruption of basalt in a lake, beach or wetland environment.
Reworked shallow water cinder cones

A

Tuff rings

57
Q

circular volcanic cones formed by the eruption of basalt in water
smaller and steeper features
Less explosive eruption, short durations

A

Tuff cones

58
Q

low relief volcanic craters that form by shallow explosive phreatomag matic eruptions
volcanic crater filled with water to create either a freshwater or saline lake

A

Maars

59
Q

The eruption of heated water and steam without magma, characterizes phreatic eruptions

A

Phreatic eruptions

60
Q

groundwater heated by proximity to magma

A

Hot springs

61
Q

eruptive hot springs that eject fountains of heated water periodically

A

Geysers

62
Q

Eruptions begin as fissures, evolving to central vent flows and the generation of large shield volcanoes.
Fiery basaltic lava fountain eruptions, quiet lava flows, and cinder cones are also generated.

A

Hawaiian

63
Q

Persistent fissure eruption of low viscosity basaltic lava flows.
Prolonged quiet eruptions may generate lava plateaus and flood basalts.

A

Icelandic

64
Q

Explosive, steam-blast eruptions with lava flows and pyroclastic debris.

A

Surtseyan
(phreatomagmatic)

65
Q

Surtseyan eruptions are named after the volcanic island of _____, which rose above sea level on November 14, 1963.

A

Surtsey

66
Q

Periodic bursts (“burps”) of moderately explosive eruptions (less than 5 km high).
These eruptions contain great concentrations of pyroclastic fragments and incandescent basaltic lava flows.

A

Strombolian

67
Q

Explosive eruptions of basaltic to rhyolitic viscous lava.
Large volumes of volcanic ash plumes (less than 25 km high) and pyroclastic debris.

A

Vulcanian

68
Q

Violent eruptions of volcanic debris ejected, scattering ash over thousands of square kilometers

A

Vesuvian

69
Q

Tephra eruptions emit immense ash clouds over 11 km in height into the stratosphere.

A

Plinian

70
Q

Violent tephra eruptions with volumes greater than 1 km³ and ash cloud heights ranging from 25 to 55 km

A

Ultraplinian