EES 105-A01

CH1 cont’d

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The Plate Tectonics

The Hypothesis:
Continental Drift: Alfred Wegener, 1912: matching fossils & rock formations

Seafloor Spreading

The Theory of Plate Tectonics: lithosphere is broken into numerous slabs called plates, which are in motion through subduction and seafloor spreading

a.    Lithosphere: 50-100 Km
Crust + portion of Upper Mantle: Strong, rigid
b.    Asthenosphere:
Uppermost Mantle below lithosphere;
Weak, plastic
c.    Convection:
Hot, less dense material to rise
Cool, dense material to sink
d.    Plate Boundaries:
Divergent
Convergent
Transform Fault
e.    Geological Activities and Plate Tectonics
Mid-Ocean Ridge
Mountain Building
Deep-Sea Trench
Volcanism
Rock Cycle
Earthquakes

~~~

Chapter 2

MINERALS: Building Blocks of Rocks

A.    What is a mineral:

  • Naturally occurring
  • Solid crystalline
  • Inorganic
  • Specific chemical composition

Crystalline: atoms arranged in an orderly, repeating , 3-dimensional manner. (Fig. 2.2)    Otherwise, glassy or amorphous

Rock: a solid aggregate or mass of minerals (Fig. 2.3)

The Atomic Structure

Atom : the smallest unit of an element that retains the physical and chemical properties of that element

The structure of atom:

  • – proton (+)
  • – neutron
  • – electron (-)

Electron shells (Fig. 2.5)
Periodic Table of Elements (Figure 2.4)


Elements arranged in groups of similar chemical properties

Chemical Bondings

a.Electron transfer- cation & anion
(Figure 2.7)

b.Chemical bonds:

  • nucleus, 3 concentric orbits: # of electrons per (carrying capacity) is 2-8-8

Ionic
Covalent (Fig. 2.8)
Metallic

B.Formation of Minerals:

By the process of crystallization, which could be initiated by three different pathways:

a.Cooling
b.Reducing the amount of solvent in a solution
c.Diffusion of ion/atom in solid (usually at temperature > 250 C)

D.    Physical Properties of Minerals

a.Crystal Form: external expression of internal structure
Left: pyrite- cubic crystal
right: Quartz- hexagonal crystal
Figure 2.12
b.Luster: the way the surface of a mineral reflects lights:

Metallic
non-metallic: vitreous (glassy), pearly, earthy.

c.Color & streak
Colors of a mineral are variable
Streak: color of the fine mineral dust left on an abrasive surface

Figure 2.26

d.Hardness: Resistance to abrasion
Mohr scale of hardness (Figure 2.13)
Sheet silicates: 1-3
most other silicates:5-7
Carbonate & sulfate: <5

Physical Properties of Minerals – Cont.

e.Cleavage: the tendency of a crystal to break along flat planar surface, i.e. plane of weakness
Described by the number and orientation (angles between adjacent planes)
Related to crystal structure
Fig. 2.14: mica

fluorite, halite, calcite

f.Specific gravity & density

g.Fracture: the feature of a broken surface of a mineral without cleavage.
Fig. 2.16. Conchoidal fracture

h.Other properties: magnetism, taste, smell, reaction to acid, etc.

C.Rock-Forming Minerals

Over 4000 minerals; ~30 make up the bulk of crustal rocks.

Fig. 2.19: Relative abundance of elements in the continental crust

8 elements make up over 80% of the continental crust

Fig. 2.22: Relative size and charges of ions

D.Classification of Minerals

Silicate Minerals: comprise most of the rock-forming minerals

Fig. 2.20. The basic unit SiO4-4, a tetrahedron

Figure 2.23: Common silicate minerals

Non-silicate Mineral Groups: Table 2.1

E.What is Asbestos?

a.Not a single mineral
b.Silicate minerals readily separate into strong fibers
c.Flexible, heat resistance, inert
d.Three major asbestos:
Chrysotile: a serpentine (white asbestos)
Crocidolite (blue asbestos)
Amosite: an amphibole (brown asbestos)

F.Important Gemstones

The Plate Tectonics

The Hypothesis:

Continental Drift: Alfred Wegener, 1912: matching fossils & rock formations

Seafloor Spreading

The Theory of Plate Tectonics: lithosphere is broken into numerous slabs called plates, which are in motion through subduction and seafloor spreading

a. Lithosphere: 50-100 Km

Crust + portion of Upper Mantle: Strong, rigid

b. Asthenosphere:

Uppermost Mantle below lithosphere;

Weak, plastic

c. Convection:

Hot, less dense material to rise

Cool, dense material to sink

d. Plate Boundaries:

Divergent

Convergent

Transform Fault

e. Geological Activities and Plate Tectonics

Mid-Ocean Ridge

Mountain Building

Deep-Sea Trench

Volcanism

Rock Cycle

Earthquakes

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