quiz 3 Flashcards
important volatiles in magma include
water and carbon dioxide
…melting occurs at subduction zones because the down-going plate…
flux ; contains abundant water
which type of magma has the greatest silica content
felsic
magma tends to…
move upward away from where it formed
viscosity controls how …
easily a fluid flows
rhyolite lava
-has more silica than basalt lava
-indicates the tendency of explosive activity
-may freeze in the vent and emerge as spine
-may form a lava dome above the vent
If the volatile content of magma is increased its viscosity will
decrease
All other factors being equal, if a body of magma becomes more feisic, its viscosity will
increase
the eruption of basaltic lava generally creates a steep feature called a lava dome like that now forming in the caldera of mt st helens
false
a batholithe is a …
amalgamation of plutons
what volcanic effusiveness is not a form of lava
lapilli
an irregular-shaped blob like igneous rock body that cooked beneath the surface of earth is a
pluton
volcanic mud-and-debris flows composed of ash debris and water
have often resulted in damage and death to humans and their property
devils tower wyoming, and shiprock New Mexico, are landforms that exist because softer volcano exterior have erroded fasterthan solidified lava in fissures and vents
true
in 79 C.E the citizens of pompeii in the roman empire were buried by pyroclastic debris dervied from the erruption of
mount Vesuvius
a lahar is
a volcanic mud and debris flow that resemble fluid concrete
volcanos whos magama source is not linked to a plate boundary are associated with …
hot spots
decompression melting occurs at both … and …
mid ocean ridges ; hotspots
mt st helens errupted in 1980 sending out gas and pyroclastic. geologist have found evidence of many eruptions of mt st helens dating back 37,000 years. this mountain is huge and is composed of layers of lava and pyroclastic.
its a stratovolcano for composite cone
if a body of magma is subjected to fractional crystalization the first rock that is expected to crystalize from the magma will be…
more mafic than the magma
volcanic arcs form along … boundaries
convergent
in bowens discontinuous reaction series, the first mineral to crystallize from a mafic melt is …
olivine
ash, and larger fragments of pumice are all examples of
pyroclastics debris
what describes architectural elements of a volcano
vent, fissure, magma chambrer, crater
what is the term for an unconsolidated accumulation of any size pyroclastic grains
tephra
as compared to coarse grained igneous rocks, fine grained igneous rocks
cool and solidify more quickly
