GEOL 1121 Unit 1 (igneous rocks and earth creation)

Earth’s atmosphere (simplified)

Volcanos spat out tons of gas, which created the atmosphere. Once the planet cooled enough, water condensed and allowed algae to grow and turn the atmosphere into something livable

Absolute time

The way that geologists measure things. Using the half life of rocks as measurements. Half lives leave behind daughter material exactly proportional to the amount lost in the half life.

Geological time scale

Phanerozoic- started 545 years ago

Proterozoic- started 2.5 billion years ago, ended 545 million

within the Phanerozoic:

Cenozoic- 66.4 million years ago

Mesozoic- 245 (ended 66.4) million

Paleozoic- 545 (ended 245) million years ago

Isotopes

elements with the correct number of protons but a varying number of neutrons

Ions

atoms with varying numbers of electrons, causing the atom to have a positive (cation) charge or negative (anion) charge

Minerals

naturally occurring, solid, organic compound with a fixed and regular internal structure (the two most popular ways to analyze minerals is by their composition and structure

Isochemical

Two or more compounds that share the same chemical composition but not structure

Isostructural

Two or more compounds that share the same structure but not chemical composition

Magma

molten rocks beneath the surface

Lava

Molten rock on earth’s surface

Phaneritic/invasive rock

rocks formed when magma seeps into the crust from below

Cool slowly over 100k-millions of years

Allows large crystals to form

Volcanic/extrusive rocks

rocks formed when lava cools above the earth’s crust

Cools rapidly over hours-days

Doesn’t allow large crystals to form

Felsic Rocks

Rocks that have a higher relative amount of Silicon in their composition than Iron or Magnesium

Rocks of this type tend to be of a lighter shade due to the Silicon content

Maphic Rocks

Rocks that have a higher relative amount of Iron and Magnesium in their composition than Silicon

Rocks of this type tend to be darker in color because of their Iron and Magnesium content

Bowen’s reaction series

The predictable cooling nature of minerals inside of rocks

(High heat 900C) - Olivine, Plagioclase

(Med heat) - Pyroxene, Amphibole

(lower heat 650C) - Quartz, K-feldspar, Boitite

Granite

Felsic, Intrusive rock

-lighter in color with large crystals

Rhyolite

Felsic, Extrusive rock

-lighter in color with too small crystals

Gabbro

Maphic, Intrusive rock

-Dark rock with large crystals

Basalt

Maphic, Extrusive

-Dark rock with large crystals

Fractional Crystallization process: Gabbro, Granite, Rhyolite

1) A maphic magma rises into the crust

2) As the magma rises, BRS says that the iron and Magnesium cool into olivine and Plagioclase

3) the Fe and Mg sink and split off the mixture as the rest continues to rise (Gabbro is created)

4) The now felsic mixture continues to rise through the crust and cools to create K-feldspar and Quartz (cools to granite)

5) if the mixture makes it to the surface and erupts, it cools into rhyolite

Fractional Crystallization process: Basalt

1) A maphic magma mixture makes its way close to the surface (thinner portion of the crust)

2) If it is able to be expelled onto the crust, it will cool into basalt