A brief introduction to minerals, rocks and the rock cycle

1. A brief introduction to minerals, rocks and the rock cycle

2. Minerals Minerals and Rocks minerals rock mineral collection of one or more minerals A collection of one or more types of atoms

3. Minerals: thebuilding Minerals blocks of rocks Definition of a mineral -> To be considered a mineral, it must: 1. Occur naturally 2. Be inorganic 3. Be a solid 4. Possess an orderly internal structure 5. Have a definite chemical composition

4. Minerals: thebuilding Minerals blocks of rocks Definition of a rock -> different from that of a mineral. A rock: 1) is solid 2) contains a mixture of one or more minerals 3) May contain a non-mineral 4) occurs naturally as part of our planet

5. Minerals: thebuilding Minerals blocks of rocks Rocks and minerals • Some rocks composed entirely of one mineral • limestone (calcite) • Most rocks have more than one kind of mineral • granite • Some rocks contain non-mineral matter • coal (has organic debris) • obsidian (volcanic glassy rock -> not crystalline)

6. The composition of minerals Minerals Granite & constituent minerals

7. Minerals • Over 4000 minerals: only few dozen are abundant, making up most rocks of Earth’s crust • => rock-forming minerals • Only 8 elements make up most of crust’s minerals & represent over 98% of the continental crust • The two most abundant elements: • Silicon (Si) • Oxygen (O)

8. Minerals Percent of elements by WEIGHT Average composition of the continental crust

9. The composition of minerals Minerals • Atomic structure 112 known elements Only 92 occur naturally

10. Mineral groups • The silicates Silicon and Oxygen combine to form the most common mineral group, the silicates. Every silicate mineral contains the elements silicon (Si) oxygen (O) Nearly every silicate mineral combines with one or more additional elements to achieve electrical neutrality

11. 1) Mineral groups • The silicates The fundamental building block of all silicates is the silicon-oxygen tetrahedron Two different views of this arrangement: silicon atom oxygen atoms

12. 1) Mineral groups The silicates Remember: Silicates are the most abundant mineral group with the silicate ion as basic building block. Light colored (crust, esp. continental crust) Non-ferromagnesian (felsic) silicates Feldspar (Si, O, Al, K, Na, Ca) - mostly white or pink 50% of earth’s crust ! Quartz (SiO2=silica) - commonly transparent silicate that consists only of silicon and oxygen second most abundant in crust! Muscovite (Si, O, Al, K, H) – most common mica cleavage in sheets, glass in Middle ages sparkle in rocks, mica flakes in sand Dark colored (mantle and oceanic crust) Olivine (Si, O, Fe, Mg, Ca)

13. Mineral groups The silicates Remember: Silicates are the most abundant mineral group with the silicate ion as basic building block. Dark colored (mantle, basalt, continental crust) Ferromagnesian (mafic) are dark silicates, contain ions of iron and/or magnesium) Olivine – black to olive green, in basalt Pyroxene – important component of earth’s mantle Hornblende – important component of continental rock Biotite – iron rich mica, component of continental rock Dark colored (mantle and oceanic crust) Olivine (Si, O, Fe, Mg, Ca)

14. Mineral groups • Important Nonsilicate Minerals Carbonates (CO3 2-) = carbonate ion Calcite (CaCO3) Dolomite (CaMg(CO3)2 Forms limestone Calcium/magnesium Carbonate, forms dolostone  found together in sedimentary rock limestone,  Main ingredient to cement, roads & building stones

15. Mineral groups • Important Nonsilicate Minerals Halides Halite (NaCl) -> common table salt Sulfates Gypsum (CaSO4-H2O) -> calcium sulfate + water, main ingredient of plaster & other building materials Oxides Hematite (Fe2O3) -> mined for iron, steel Ice (H2O) -> solid form of water

16. Rocks Three major types of rock

17. Rock cycle and the three basic rock groups. From Tarbuck, Lutgens: Earth

18. The rock cycle is an interaction between Climate and Plate Tectonic System From Press, Siever: Understanding Earth, 4th edition

19. Rocks Extrusive-Intrusive Igneous rocks Extrusive rocks are formed at the surface from lava, rapidly cooling, small crystals, fine-grained texture. Intrusive rocks are formed from magma in Earth’s crust, slow cooling, large crystals, coarse texture.

20. Sedimentary rocks How to make a sedimentary rock. Diagenesis Any physical and chemical change that happens to the sediments or the sedimentary rock

21. How to make a metamorphic rock. Transform: Igneous Sedimentary Metamorphic into: “process” Metamorphic occurs deep Recall: 3 fundamental rock types “metamorphism” Lit. “change form”

22. Metamorphic rocks Metamorphic rocks form under 4 main conditions: Rocks Contact Ultra high P Regional high P High P, Low T

23. TODAY: Plate Tectonics (Part I) • Intro: Chemical and physical structure of Earth • 1) The plate tectonic system • 2) A theory is born • 3) Early evidence for continental drift Read Chapter 3!

24. Earth’s layer by chemical properties Earth’s layering by chemical properties Crust Mantle Core

25. Earth’s layer by physical properties Lithosphere and asthenosphere Lithosphere: Crust and uppermost mantle. Broken into 12 plates. Brittle, rigid. 1-100km Asthenosphere: Lower portion of upper mantle, down to 660km Soft, deformable, small amount of melting. 3-18

27. 1) The plate tectonic system Fig. 3.10 • The lithosphere is the outer rigid shell of earth, about 100km thick. It is broken into a dozen large plates that move on the plastic asthenosphere (lower part of the upper mantle) • The lithosphere is created at mid-ocean spreading centers and subducts when converging with another plate. • The driving force of this movement are convection currents in the asthenosphere.

28. 1) The plate tectonic system Convection

29. 1) The plate tectonic system PLATE TECTONICS 1) Overview Compare with Fig. 3-14