chapter 4 test 1 Flashcards
igneous rocks
form as molten rock cools and solidifies
extrusive igneous
rocks formed from lava that cools at the surface
intrusive igneous
rocks formed from magma that crystalizes at depths (plutonic)
liquid melt
mobile ions
solids
silicate minerals that have already crystalized from the melt
volatiles
gases dissolved in the melt
fine grained texture
rapid rate of cooling of lava or magma
microscopic crystals
may contain vesicles
coarse grained
slow cooling crystals can be identified without a microscope
porpyritic texture
minerals form at different cooling temps as well as differing rates
large crystals called phenocrysts
glassy texture
very rapid cooling of molten rock
pyroclastic texture
various fragments ejected during a violent volcanic eruption
vesicular texture
spherical openings called vesicles
common extrusive igneous rocks
felsic
granite composition
light colored minerals
has feldspar and silica
viscous
mafic
basaltic composition dark minerals
magnesium and ferrum
more dense than granite rocks
less viscous
obsidian
dark colored
glassy texture
pumice
volcanic
glassy texture
frothy appearance with numerous voids
pyroclastic rock
composed of fragments ejected during a volcanic eruption
tuff-ash sized fragments
volcanic breccia
magmatic differentiation
seperation of melt from earlier formed crystals to form a different composition of magma
assimilation
changing a magmas composition by the incorporation of foreign matter into magma
magam mixing
involves 2 bodies of magma intruding one another
plutons shape
sheet like (tabular), massive
orientation
discordant-cuts across sedimentary rock units
concordant-parallel to sedimentary rock units
dike
a tabular, discordant pluton
sill
a tabular, concordant pluton
laccolith
similar to a sill, lens or mushroom shaped mass
batholith
largest intrusive body, frequently form the cores of mountains
columnar joints
produced by contraction and fracturing in lava flow or sill
magmatic segregation
seperation fo heavy minerals in magma chamber
hydrothermal solutions
originate from hot, metal rick fluids that are remnants of the late stage magmatic process
phaneritic rocks
intrusive and cooled below the surface, significant crystal growth
aphanitic rocks
small crystals, course, cooled quicly
