Term
|
Definition
Mainly rhyolitic lava
Smaller vol.
After lg violent eruptions
Ex. St helens, mt pelee, mono craters |
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Term
|
Definition
Mainly pyroclastics
Smaller, steep sided,up to 40deg
any composition
portland hills |
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Term
|
Definition
| erupted in the last 10,000 yrs |
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Term
|
Definition
| geothermal energy but no eruption in the last 10,000yrs. |
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Term
|
Definition
| no geothermal and no possibility of eruption |
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Term
|
Definition
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Term
|
Definition
| magma that lost its gases |
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Term
|
Definition
mainly water
CO2, N, SO2, HCl, S, Cl |
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Term
|
Definition
| ash, cinder, lapilli, volcano bombs |
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Term
| where are volcanos located |
|
Definition
15% divergent margins
80% convergent margins (ring of fire)- mostly composite volcanoes on subduction zones
5% within plates (Hot spots)- Hawaii, Iceland, mafic magmas |
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Term
|
Definition
shield volcano
plateau basalts
lava forms
lava tube caves |
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Term
|
Definition
basalt
low angles (up to 5d)
lava flows over lava flows
many oceanic
-mauna loa, mauna kea |
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Term
|
Definition
fissure eruptions
magma out of a fissure and floods area
columbia rv plateau |
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Term
|
Definition
pahoehoe-smooth ropy, satin flows (from high temp magma)
aa- rough broken surface, more viscous magma, lower temp
pillow lava- formed under water |
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Term
|
Definition
common in basalt.
ape caves- st. helens
bend |
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Term
|
Definition
composite volcano
cinder cones
domes
nuee ardente
caldera |
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Term
|
Definition
alternating lava and pyroclastics.
1. mainly andesite
2. steep sided (30d)
3. subduction zones
-cascades, andes, aleutians, japan |
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Term
|
Definition
fiery cloud eruption
-mainly gases and hot pyroclastics
mainly in caribean |
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Term
|
Definition
collapsed compossite volcano after violent erption
-crater lake, yellowstone, krakatoa,vesuvius
lost continent of atlantis |
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Term
|
Definition
| steam vents, lots of dissolved elements |
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Term
|
Definition
| groundwater heated by hot rocks or deep faults below |
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Term
|
Definition
| hot springs that erupt into the air; old faithful |
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Term
|
Definition
lava flows,
tephra (pyroclastics)
lahars (debris flows)- in stream valleys- start from melting snow and ice with pyroclastics on mountain
flooding
silting of rivers
earthquakes
erosion
tsunami
climate change
debris avalanches
volcanic gases |
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Term
|
Definition
monitor:
ground deformations
earthquake swarms
ground temp increases
fumaroles
magnetic field lows- show magma |
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Term
|
Definition
dark minerals like olivine and pyroxene.
low in silica
dark color due to ferromagnesium
basalt, gabbro |
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Term
|
Definition
silicic= rich in silica
light colored minerals like quartz and feldspar |
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Term
|
Definition
size shape arrangement of the mineral grains.
crystals will tell if it's fast or slow cooling
aphanitic
phaneritic
pegmatitic |
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Term
|
Definition
| rapid cooling. can't see crystals with the naled eye. EXTRUSIVE. |
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Term
|
Definition
can see crystals with naked eye
INTRUSIVE
Slow cooling (thousands and millions of yrs)= plutonic |
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Term
|
Definition
very lg. grains. Slow cooling lots of water in magma.
gold, copper, lead, Zn |
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Term
|
Definition
non-crystalline abrasive. EXTRUSIVE
Obsidian: black glass, magma into water so very rapid cooling. Felsic (dark color due to impurities
pumice: white. many holes so it floats |
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Term
|
Definition
2 grain sizes. slow cooling followed by rapid cooling.
common in composite volcanes |
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Term
|
Definition
Mafic,
extrusive
aphanitic
Most common volcanic rock |
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Term
|
Definition
90% of intrusive rocks. slow moving magma that doesn't make it to the surface.most common INTRUSIVE.
felsic
phaneritic
Great building stone |
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Term
|
Definition
intermediate silicic.
aphanitic
extrusive
named in Andes
formed at convergent margins |
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Term
|
Definition
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Term
|
Definition
| vesicular, fine grained. surface |
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Term
|
Definition
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Term
|
Definition
basalt with vesicles. weathered basalt
flow top
weathers to brown and red |
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Term
|
Definition
vertical cracks in basalt from cooling: polygonal cracks
mafic magma from deep undersurface.
cools from bottom up and top down.
RED FLAG: Basalt as bedrock can be columnar jointing and is NOT goos to build on.
Teton Dam Disaster. grout used to keep water out failed |
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|
Term
engineering characteristics of igneous rocks:
INTRUSIVE |
|
Definition
Strength: high to very high-16,000-32,000psi
deformation and failure: elastic plastic |
|
|
Term
engineering characteristics of igneous rocks:
EXTRUSIVE MASSIVE |
|
Definition
flows, dikes, sills,
strength:high 16,000-32,000psi
deformation and failure: elastic |
|
|
Term
engineering characteristics of igneous rocks:
EXTRUSIVE POROUS |
|
Definition
vesicles: tuff, breccia, pumice, scoria
NOT good to build with
rock strength, very low to low:0-8000psi
plastic-elastic |
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Term
|
Definition
intrusive rock structure (mainly granite)
younger than surrounding rocks |
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Term
|
Definition
volcanic plugs
sill
dike
laccolith |
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Term
|
Definition
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Term
|
Definition
| dikes filled with minerals (sulfide minerals: gold, copper, Zn) |
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Term
|
Definition
eroded neck of volcano
devils tower
ship rock
beacon rock |
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Term
|
Definition
tabular pluton sheet btwn sedimentary beds; concordant; parallel
magma btwn layers of shale
Palasides sill, Great Whin (Hadrian's Wall-UK) cemetary ridge- battle of gettysberg |
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Term
|
Definition
discordant pluton; injected in fissures in older rocks, cuts across features
weathers slower than surrounding rock |
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Term
|
Definition
thick domed sill
lasal mts. and henry mts. |
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Term
|
Definition
lg. massive pluton <80km^2 at surface
old magma chambers
almost always granite |
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Term
|
Definition
>80km2
sierra nevadas
mostly granite |
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