Igneous Rocks
Intrusive
Plutonic
Magma cools and crystallizes within the earth
Different Types of Cooling
Slow
thousands to millions of years
below earths surface
mineral can be seen with naked eye
phaneritic texture
Fast
Days to weeks
Happens at earths surface
microscopic in size
fine grained mineral textture
aphanitic texture
Very fast
Hours to days
no minerals grow
elements are frozen in place
results in glass
Slow followed by fast
larger and smaller crystals
smooth grained crystal matrix and large crystal structure
porphyritic texture
Volcanic eruptions are based on
volume of material
degree of fragmentation of the airborne volcanic products
height of eruptive column
height of plume head
explosive vs non-explosive
non explosive are called Hawaiian eruptions
Strombolian are short and eruptive that burst viscous basaltic lava
places ingneous rocks are found
ocean plates- basalt and gabbro
continets- granite
volcanic arcs- andesite and diorite
how ingenious rocks are formed
inside earth is molten magma
when magma reacts the surface it is called lava
when it cools it solidifies to form igneous rock such as granite or basalt
eight minerals that form ingneous rocks
olivine, pyroxene, amphibole, biotite, orthoclase, muscovite, quartz, feldspar
Feldspar has two different types- sodium plagioclase and calcium plagioclase
silica content
felsic also called acidic has a high silica content and a low iron and magnesium content
Mafic also called basic has a low silica content and a high iron and magnesium content
vocab
pilian eruptions: produce dacitic or rhyolitc lava
tephra: term for all airborne particles from a volcano
pyroclasts: airborne fragments from a volcano
Extrusive
Volcanic
Magma cools and crystallizes on the earths surface
levels of viscosity
higher the temp the less viscous
the higher the silicon dioxide level the more viscous
when viscous
usually becomes basalt
gas can be released easily
gas bubbles remaining are called vesicles
intrusive rocks
form in the mantle
contain olivine and pyroxene
are green and black
less than 45 percent silica
Dunite and peridotite
extrusive
formed by volcanoes
magic, intermediate or felsic
mafic
basic
mostly in oceans
dark grey
pyroxene and calcium plagioclase
basalt and gabbro
intermediate
plagioclase
more white than mafic
sodium present
felsic
acid
lots of minerals like quartz and feldspar
light grey
magnesium and iron add colour variations
granite and rhyolite