Rocks

Rocks Lecture

  • Rocks - substances mad euphoria of one or more minerals

    • Mineralogy of a rock

    • Texture

      • 3 great rock groups

Average Geothermal Gradient

  • 1 degree Celsius / 100 ft depth

  • Pieces of the Earth’s crust are called plates

Magma or lava (cool and crystallization) → Igneous Rocks (weathering and erosion) → Sediment (lithification) - Sedimentary Rock (heat + pressure - Metamorphism) → Metamorphic Rock (melting → back to magma

(side bar any rock can turn into sedamentary rock)

Plates

  • Plate tectonics

    • They move and interact with each other (slow but violent)

Igneous Rocks

  • Igneous rocks - form form the crystallization of molten rock (either magma or lava)

  • Average GeoThermal Gradient - the deeper you go the hotter it gets (the worldwide average of it) 1 degree celsius/ 100 feet depth


  • form from the cooling and crystallization of molten rock. When minerals grow
    directly from a liquid the boundaries between adjacent minerals tend to penetrate each other,
    forming a very strong, interlocking pattern similar to that of pieces in a jigsaw puzzle. Given
    this and the fact that igneous rocks are composed of relatively hard (for the most part) silicate
    minerals, igneous rocks are very hard rocks that have been used as major building materials by
    people for 1000s of years.

    • heat is caused by radiation

  • Mineralogy -

    • When it comes to the Earths crust 75% is made up of just 2 elements

      • Silicon & Oxygen

    • 24% is 8 other metals

      • calcium

      • Magnesium

      • Iron

      • Sodium

      • Aluminum

      • Potassium

Bowens Reaction Series

How does magmatic differentiation occur?

  • basically how do we get different igneous rocks from the same chunk

  • So to answer the question we have to picture a deep crack in the earth and approx 20 miles down we make magma

  • SO imma upload a picture on my phone bc i zoned out < /3

  • Bowen calls the process - Fractional Crystallization

  • Doesn’t explain everything

    • Just XENOLITHS

      • Assimilation

Different kidns of Granite are formed via contaminations

Dunite v Dunite Magma

  • Can be differentiated via texture

    • and mineralogy

Sedimentary Rock

  • ~ 5% of all rocks

  • 75% of the Earth Surface

Sediment = “pieces”

  • 90% - Detrital Sediment

    • Detrital Sediment - pieces of pre-existing rock (Detrital Sedimentary Rock)

  • 10% - Nondetrital Sediment

    • Nondetrital Sediment - hard part "(pieces) of pre-existing life

Detrital Sediment

  • Weathering = break down of pre-existing rock

    • Physical weathering

      • Frost wedging = Freezing of expanding liquid water, applying a force to break up rock

        • Exactly like Nivation but this is the general term, it’s not location specific like Nivation

      • Abrasion - physical force of moving something and slamming it into something else

      • Plant root pressure - roots of plants move things around and break things up

    • Chemical Weathering

      • Acidation - ass acid to rock (carbonic acid)

      • Oxidation - chemically rust minerals

      • Hydration - chemically add water to rocks

Think Vander Waals Forces

  • the primary force that holds things together in a water molecule

    • the plus and minus magnetic field of the compound

  • think about the formation of clay

    • Waters magnetic nature has pulled metals out of minerals

    • forming clay

Recipe for making Detrital Sedimentary Rock

  • 1) Weathering (makes soil)

  • 2) Erosion = transportation (Detrital Sediment)

  • 3) Deposition

  • 4) Lithification

    • Lithification - Compaction and Dehydration

      • Ex) making clay into a rock then pile a bunch of it up = shale

      • Ex) Quarts sand - Cementation of some minerals = sandstone

Nondetrital Sediment

  • 2 major categories of life

    • Plants

    • Animals

  • Animal Life

    • most animals are in the Sea

    • Seashells

      • Seashells are made up of Calcite

        • Susceptible to being dissolved by acidic water

        • dissolves some of the calcite → making calcite seashells cementing with Calcite

      • Really old seashells are known as fossil limestones?? I think.

  • Plant Life

    • CHONS is in PLANTS AND ANIMALS

      • Carbon Hydrogen Oxygen Nitrogen and Sulfur

      • the gasses go away over time and the solids compact over time and become mostly carbon

Metamorphic Rock

  • it’s way down deep

    • about 3 mi deep

  • Protolist = first rock

  • Metamorphism

    • High temperature (Solid State)

    • High pressure = Kilobar

      • bar = 14.7 psi

    • Chemically active fluids and gases

      • Volatiles

  • Temp

    • denatures and chemically changes

  • Pressure

    • recrystallized

    • rotate and realign

    • LIKE FOLIAGE

    • called Foliated texture (peel old layer to get new layer)

  • Volatiles

    • Recrystallize

We see a thing called Regional Metamorphism

  • Regional metamorphism is a type of metamorphism that occurs over large areas and is typically associated with tectonic forces that apply significant pressure and temperature conditions, often resulting in the formation of foliation in rocks. This process can lead to the recrystallization of minerals and changes in the rock structure and composition due to elevated temperatures and pressures deep within the Earth's crust.

when clays grow in size and we can see them they change names

  • now called Micas

    • Muscovite/ biotite

      • most common types of Micas

Shale protolist = Schist

granit protolith = Gneiss (nice)