CEE 437, Fall Quarter 2006
Study Question List #1 Earth Structure, Minerals, and Rocks
Plate Tectonics and Earth Structure
Sources: West Chapter 1., USGS Dynamic Earth
(pubs.usgs.gov/publications/text/dynamic.html)
What are the main differences between mantle, continental, crust, and oceanic crusts in
terms of
a. age
b. chemical composition
c. rock types found
What are the primary mechanisms thought to be driving plate tectonics?
Understand basics of convergent margins, spreading centers, and subduction zones.
Understand major supporting arguments for plate tectonics
What is sea-floor spreading and the evidence for it?
Understand how plate tectonics affects Pacific Northwest
Draw EW crustal cross section across Washington state showing the subduction
zone, Cascade volcanoes, older plutons; how to the Olympic Mountains fit in?
Where are such processes as magmatism and metamorphism taking place?
What is a “hot spot” in plate teconics. Give an example from the Pacific Northwest.
Principles of Differentiation (Lecture)
Differentiation is a process that separates one type of material from another,
concentrating certain things in one place and excluding others. Some differentiation
mechanisms are:
Magmatic differentiation (Bowen’s reaction series)
Weathering processes (Goldrich stability series – see West Ch.8, p154 ff)
Sedimentary differentiation – deposition and transport processes segregate
materials
Minerals
Sources: West Ch. 2Turner, et al, The Earth, reading on mineral properties;
Horseman, et al, Water Gas and Solute Movement through Agillaceous Media, Ch 2
(Class web site)
What defines and mineral and what are some examples of earth materials that are not
minerals?
a. What are the main rock forming silicate minerals (quartz, feldspars
[plagioclase, orthoclase], ferromagnesian silicates [olivine, pyroxenes,
amphiboles].
b. What are the most common elements in crustal composition and how are they
distributed among common rock forming minerals (e.g. quartz, feldspars,
ferromagnesian minerals )
c. What are the key weathering products of rock forming minerals e.g. feldspars,
quartz, and ferromagnesian minerals.
What is the silica tetrahedron?
a. What different forms of linkages can tetrahedra make, and what minerals are
they associated with (e.g. isolated tetrahedra, chains, frameworks, sheets)
b. How does the structure of the silica tetrahedra linkages affect rock properties
and what are some examples?
c. How is the structure of silica tetrahedra related to mineral chemistry?
What are some simple physical properties used for mineral identification (West p. 20,
Appendix A, Turner, p. 92)
How does the crystal lattice affect rock properties in terms of anisotropy; which crystal
groups will not show anisotropic behavior (Turner)?
a. velocity
b. light transmission
c. elasticity
d. thermal expansion
If a rock is made of several mineral types (say a typical granite) how would the
anisotropy of properties and differences among different minerals affect say the behavior
of the rock under load or while undergoing heating and cooling?
How does plastic flow relate to crystal structure (Turner)?
Describe and derive Bragg’s Law of diffraction and how it can be used for mineral
identification (Turner)
What are the main minerals that form at the surface from chemical or biological
processes (carbonates and evaporites). What types of engineering problems relate to their
solubility and volume changes with hydration?
What are the main sheet silicate minerals and discuss their engineering significance.
a. how are micas and clays similar and different
b. what are the main clay mineral groups, what distinguishes their crystalline
structure, and how do these distinctions affect their engineering properties
(Horseman and West, Ch 2.) (distinction of 1:1 and 2:1 clay minerals, some
examples)
c. Describe bentonite and discuss its properties
Minerals to know (so geologists won’t make fun of you) including distinguishing
characteristics, general properties,
Calcite/dolomite (dolomite is just like calcite but with 50% substitution of Mg for
Ca
Quartz
Feldspar (be aware of variants orthoclase/k-feldspar and plagioclase)
Mica (be aware of variants, muscovite and biotite)
Halite (Rocksalt)
Gypsum (Anydrite – gypsum is hydrous, big volume change cases engineering
problems)
Clays (and major variants kaolinite, illite, smectite, montmorillonite)
Pyrite
Be aware of ferromagnesians olivine, pyroxene, amphibole
Rocks
Sources:West, Chapters 3-5
General: Understand the Rock Cycle (Figure 5.1)
Igneous Rocks: (West Ch. 3)
How are igneous rock classified in terms of chemical/mineral composition and texture?
Chemistry: ultramafic, mafic, intermediate, acidic
Texture: aphanitic, phaneritic (you don’t need to memorize these terms)
How does does texture distinguish extrusive and intrusive/plutonic rocks?
Key rocks to know: granite (and know it had variants), diorite, gabbro, serpentinite
basalt, andesite, rhyolite, tuff
Sedimentary Rocks: (West Ch. 4)
Distinguish clastic, carbonate, organic (coal, lignite), and evaporite rocks
Understand roles of bedding and cementation in rock properties
For clastics:
Know classification by grain size
Be aware of sorting as an issue (grain size distribution)
Know general variation of depositional environments (high energy or low energy)
Understand organic origins of limestones
Understand basic bedding types and their significance: cross bedding, graded bedding
Understand role of cementation and its effect on rock properties
Understand concept of sediment “maturity”.
Understand briefly concept of sedimentary facies (page 66, a facies is a zone of
deposition that moves laterally with shifts in sea level)
Key clastic rock types and sediment sources:
Conglomerate/gravel
Sandstone/sand
Siltstone/silt
Mudstone-Claystone-Shale/clay-sized sediments (mudstone is regardless of composition,
claystone has lots of clay, shale is strong bedding anisotropy while others are more
massive)
For carbonate rocks:
Understand the carbonate rocks are actually clastics but made of carbonate debris
Appreciate solubility issues and effect on engineering
Recognize dolomitization (post-depositional replacement of calcite with dolomite)
Chalk is a highly porous limestones entirely made of shells of microorganisms.
Microorganisms that produce silica shells create a rock called “diatomite”.
Evaporites:
Understand origin of rock salt and gypsum through evaporation in restricted flow setting.
Appreciate solution problems associated with evaporite deposits.
Understand plasticity of rock salt and diapirism (formation of salt domes from density
instabilities).
Metamorphic Rocks, West Chapter 5, Exercise Questions 1, 6, 7, 8
Understand basis of metamorphism as solid state recrystallization under temperature and
pressure.
Relate metamorphic rock types to source equivalents:
Shale/Claystone → phyllite→schist→gneiss
Limestone/Dolomite→ marble
Sandstone→quartzite
Basalt→greenshist
Understand particular role of anisotropy of engineering properties due to preferred
orientation of crystallization under pressure (particularly orientation of micas)