A brief introduction to minerals rocks and the

A brief introduction to minerals, rocks and the rock cycle

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

Minerals: the building blocks of rocks Minerals 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

Minerals: the building 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

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

Minerals Granite & constituent minerals The composition of minerals

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: n Silicon (Si) n Oxygen (O)

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

Minerals The composition of minerals F Atomic structure 112 known elements Only 92 occur naturally

Mineral groups F 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

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

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 (Si. O 2 =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

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 Pyroxene Hornblende Biotite – black to olive green, in basalt – important component of earth’s mantle – important component of continental rock – iron rich mica, component of continental rock

Mineral groups F Important Nonsilicate Minerals Carbonates (CO ) = carbonate ion 3 2 - Calcite (Ca. CO ) Forms limestone Dolomite (Ca. Mg(CO ) Calcium/magnesium Carbonate, forms dolostone 3 3 2 found together in sedimentary rock limestone, Main ingredient to cement, roads & building stones

Mineral groups F Important Nonsilicate Minerals Halides Halite (Na. Cl) -> common table salt Sulfates Gypsum (Ca. SO 4 -H 2 O) -> calcium sulfate + water, main ingredient of plaster & other building materials Oxides Hematite (Fe 2 O 3) -> mined for iron, steel Ice (H 2 O) -> solid form of water

Rocks Three major types of rock

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

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

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

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

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

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

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!

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

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

1) The plate tectonic system Fig. 3. 10 1. The lithosphere is the outer rigid shell of earth, about 100 km thick. It is broken into a dozen large plates that move on the plastic asthenosphere (lower part of the upper mantle) 2. The lithosphere is created at mid-ocean spreading centers and subducts when converging with another plate. 3. The driving force of this movement are convection currents in the asthenosphere.

1) The plate tectonic system Convection

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