Mantle convection animation radiant energy

from decay in Earth’s core

hypothesis: CONVECTION CURRENTS IN THE MANTLE DRIVELITHOSPERE PLATE MOVEMENT

Infer: Unequal heating of the mantle material causes rock to flow in convention currents

IGNEOUS ROCKS ARE FORMED FROM MAGMA IN THE LITHOSPHERE

extruding magma = lava

granite

basaltMagma contains minerals that form crystals during cooling

• slow to cool• visible crystals

Cools within the lithosphere

INTRUSIVE IGNEOUS

gabbro

• Quick to cool • microcrystal formation glassy, even

EXTRUSIVE IGNEOUS

Cool outside the lithosphere (air/water)

obsidian

lava

magma

magma

ONE MAGMA POOL, TWO IGNEOUS PROCESSES

andesite

diorite

• One magma pool can create both intrusive and extrusive rocks

• differ in crystal size, but not chemistry

ONE MAGMA POOL, CHEMICALLY DIFFERENT ROCKS

• Melt/crystallization temp varies from mineral to mineral

• As rocks are formed, partial melting can occur, and magma chemistry changes

• Next rocks to form reflect new chemistry

melt and crystallize at a higher temp

melt/crystallize at a lower temp

ONE MAGMA POOL, CHEMICALLY DIFFERENT ROCKS

1400 F

800 F

Plate material heated to 1000F, then cooled, would produce what rock types?

MAJOR MAGMA TYPES

• granitic – highest SiO2, >70%

Magma is defined by it’s silicate – SiO2 - concentration

• basaltic – lowest SiO2, <50%

• andesitic – medium SiO2 partial melting of basalt and granitic

basalt

andesiterhyolite