Igneous Rocks Flashcards
What texture is phaneritic?
course cyrtsalline
What texture is aphanitic?
fine grain
What texture is pgematic?
big crystals, bigger than 1 cm
What texture is vesicular?
has holes/vesicles
What texture is porphyritic?
mix of big & small crystals
What is an example of a mafic, vesicular rock?
scoria
What is an example of a mafic, fine textured, crystalline rock?
basalt
What is an example of a mafic course grain, crystalline rock?
Gabbro
What is an example of a felsic, vesicular rock?
pumic
What is an example of a felsic, glassy rock?
obsedian
What is an example of a felsic fine grain, crystalline rock?
ryolite
What is an example of a felsic, course, crystalline rock?
granity
What is an example of a felsic, very course, crystalline rock?
pegmatite
Does a viscous lava flow easily or not?
Not
Does mafic or felsic lava flows viscous or more readily?
Felsic is viscous, mafic is more readily
Describe a sill
Intrusive, mafic, flat/tabular shape. Concordant.
Describe laccolith
Intrusive, felsic, mushroom shaped, concordant
Describe batholith
Intrusive, felsic, bottom-less, large/huge scale (upside-down bathtub)
Describe dike
Intrusive, mafic OR felsic, small scale, offshoots from bigger pools, discordant (cuts across layers) Can also feed a laccolith
What do you call an intrusive lava flow that has an indescribable shape?
pluton
What does andesitic mean?
felsic/mafic mix
What does the Bowen rxn series tell us? What is the mineral that is the first to form?
What minerals crystallize @ what temperatures.
Olivine
In the context of Bowen rxn series, what is fractionation?
The cooling FIRST of the outside edges (olivine first), and the mineral that forms pulls elements from the pool so that the chem composition of the pool changes slightly.
Is the bottom or top of the Bowen rxn series more stable?
Bottom, which is why quartz is everywhere (like at the beach). You hardly see olivine in sedimentary rocks.
Study Bowen’s Rxn Series
Pew pew pew
What is this rock?
Scoria
Study this classification table
Ooo
What are these two rocks and why are they similar?
Rhyolite (on the right) is the volcanic equivalent of granite (on the left). Both consists of light colored silicates.
The statements that follow relate to terms describing igneous rock textures. For each statement, identify the appropriate term:
a. Opening produced by escaping gas
b. Obsedian exhibits this texture
c. A matrix of fine crystals surrounding phenocrysts
d. Crystals are too small to be seen with the naked eye
e. A texture characterized by two distinctly different crystal sized.
f. Course grained, with crystals of roughly equal size
a. vesicular
b. glassy
c. groundmass
d. aphanitic
e. porphyritic
f. phaneritic
What does a porphyritic texture indicate about igneous rock?
Since all minerals within a magma do not crystallize at the same rate at the same time during cooling, it is poss for some crystals to become quite large before others start to form.W
What is the difference between magma and lava?
Lava is magma that has reached the surface
An igneous rock with an aphaneritic texture was most likely intrusive. T/F
F
Mafic igneous rocks are generally dark in color and relatively rich in iron and magnesium. T/F
T
A mafic, flat, tabular, concordant igneous intrusion is called:
A) batholith
B) laccolith
C) Sill
D) Dike
E) none of the above
C) Sill
