Categories: All - texture - igneous - cooling - magma

by Griggs Griggs 5 years ago

186

U2A1

Igneous rocks are formed through the cooling and solidification of magma, either on the earth's surface or beneath it. When magma cools on the surface, it becomes extrusive, often resulting in rocks like basalt, which may contain vesicles formed by trapped gas bubbles.

U2A1

Igneous Rocks

felsic

granite and rhyolite
magnesium and iron add colour variations
light grey
lots of minerals like quartz and feldspar
acid

intermediate

sodium present
more white than mafic
plagioclase

mafic

basalt and gabbro
pyroxene and calcium plagioclase
dark grey
mostly in oceans
basic

extrusive

magic, intermediate or felsic
formed by volcanoes

intrusive rocks

Dunite and peridotite
less than 45 percent silica
are green and black
contain olivine and pyroxene
form in the mantle

when viscous

gas bubbles remaining are called vesicles
gas can be released easily
usually becomes basalt

levels of viscosity

the higher the silicon dioxide level the more viscous
higher the temp the less viscous

Extrusive

Magma cools and crystallizes on the earths surface
Volcanic

vocab

pyroclasts: airborne fragments from a volcano
tephra: term for all airborne particles from a volcano
pilian eruptions: produce dacitic or rhyolitc lava

silica content

Mafic also called basic has a low silica content and a high iron and magnesium content
felsic also called acidic has a high silica content and a low iron and magnesium content

eight minerals that form ingneous rocks

Feldspar has two different types- sodium plagioclase and calcium plagioclase
olivine, pyroxene, amphibole, biotite, orthoclase, muscovite, quartz, feldspar

how ingenious rocks are formed

when it cools it solidifies to form igneous rock such as granite or basalt
when magma reacts the surface it is called lava
inside earth is molten magma

places ingneous rocks are found

volcanic arcs- andesite and diorite
continets- granite
ocean plates- basalt and gabbro

explosive vs non-explosive

Strombolian are short and eruptive that burst viscous basaltic lava
non explosive are called Hawaiian eruptions

Volcanic eruptions are based on

height of plume head
height of eruptive column
degree of fragmentation of the airborne volcanic products
volume of material

Different Types of Cooling

Slow followed by fast
porphyritic texture
smooth grained crystal matrix and large crystal structure
larger and smaller crystals
Very fast
results in glass
elements are frozen in place
no minerals grow
Hours to days
Fast
aphanitic texture
fine grained mineral textture
microscopic in size
Happens at earths surface
Days to weeks
Slow
phaneritic texture
mineral can be seen with naked eye
below earths surface
thousands to millions of years

Intrusive

Magma cools and crystallizes within the earth
Plutonic