Class Notes:

Sediments and Sedimentary Rocks

Sedimentary rocks are:

How to make a Sedimentary Rock

1) ________________ of pre-existing rock

2) ____________ &_______________ of weathering by-products

3) Deposition or Precipitation to form __________________

4) ________________ (diagenesis) of sediment to form Sedimentary Rock

Weathering products include:

________________

________________

Some Erosional-Transportation-Depositional Processes

1) Rivers

2) Waves

3) Wind

4) Glaciers

5) Gravity (e.g. Landslides)

______________________: the process by which sediment becomes rock

1)

2)

Types of Sediment (and sedimentary rock)

1) _____________:transported and deposited as solid

2) _____________:precipitated inorganically from solution

3) _____________:precipitated organically from solution

Sediments and Rocks are classified on the basis of:

1) ________________

2) ________________

Types of major textures of sedimentary rocks include:

1)

2)

Clastic Textures include:

1) Grain ______

2) Grain ______

3) Grain ______

Size Range	Particle name	Common sediment name	Sedimentary Rock
>2mm
1/16< >2mm
< 1/16 mm

Conglomerate (fig.7.6)

Breccia (fig. 7.7)

Sandstone (fig. 7.4)

Shale

Relative abundance of sedimentary rock types

Note variability in composition of sand

_____________: almost all quartz grains

_________________:feldspar-rich sandstone

Q. What type of igneous rock might be the source of an arkose?

A.

Q. Could that same rock be the source of a quartz arenite, and if so, in what conditions?

A.

What is the significance of Grain Size, Shape, and Sorting?

Significance of Grain Size?

_____________________ occurs when applied forces (velocity) exceeds resisting forces of particles at rest.

The larger (heavier) the particle, the larger the resisting force.

Therefore, the greater the energy (velocity) needed to erode and transport the particle.

The greater the wind or water velocity, the larger the particle which can be transported.

e.g. > 50 cm/sec can transport up to ________

20-50 cm/sec can transport up to ________

< 20cm/sec can transport only ________

(excludes glaciers!)

____________________ occurs when energy (velocity) decreases below that needed to move the particle.

Size and Depositional Environment

______ can only transport and deposit sand-sized particles

_______ and _______usually transport and deposit sand, but under high energy conditions, can transport gravel as well

__________ can transport ANY sized particles, from dust to pieces of a mountain!

Significance of Grain Shape?

1) ____________ is more effective than water in rounding sand-sized particles

2) The _______________ the distance of transport, greater the amount of rounding

3) Softer fragments round faster than harder fragments

Q. What is the significance of a conglomerate verses a breccia?

A.

_________________________: measures variability of grain size

_______________ percent void space

_______________ measures the ease with which a fluid flows through a rock

Significance of Grain Sorting?

__________________ sediment has been rapidly deposited, with little reworking (e.g. landslide, glaciers)

__________________sediment has been extensively reworked (e.g. wind, waves)

A _____________________is a geographic location characterized by a particular combination of geologic processes and environmental conditions.

Common Sedimentary Environments (fig. 7.19)

Erosional-Transportation-Depositional Processes

Rivers

Waves

Wind

Glaciers

Gravity(e.g. Landslides)

Talus Slope: process and product =

Glacier: process and product =

High energy mountain stream: process and product =

Lower energy stream: process and product =

Desert dunes: process and product =

Galveston beach: process and product =

Indicators of clastic depositional environments include:

1) Grain Size

2) Grain Sorting Texture

3) Grain Shape

4) Bedforms (e.g. ripples)

5) Sedimentary Structures (e.g. cross bedding)

6) Fossils

Ripple Marks: a type of Bedform

How do you distinguish Wave- and Current-formed Ripples?

Q. What is the significance of mudcracks?

A.

Q. How does cross-bedding form?

A.

Cross-bedded windblown sand

Cross-bedded windblown sandstone

Fossils as indicators of depositional environment

Types of Chemical Precipitation

1) __________________ e.g.

a) Most Limestones including Coquina, Chalk)

b) Some Chert

c) Coal

2) __________________: e.g.

a) Some Limestones: e.g. Travertine

b) Most Cherts

c) Evaporites: (e.g. Calcite, Gypsum, Halite, “Bitterns”, Nitrates)

Limestone cliffs in the Grand Canyon

El Capitan Peak (highest point in Texas) originated as a _________

Coral reef surrounding volcanic island

Shells fragments are an example of biochemical sediment

What is Coquina and how does it form?

What is Chalk and how does it form? (figure 7.9)

What is Travertine and how does it form?

What is Chert and how does it form?

What are Evaporites?

What is a playa?

Halite (figure 7.13)

What is a 10:20:10Fertilizer?

10 parts ___________

20 parts ____________

10 parts _____________

Sequence of Precipitation from the Evaporation of Sea Water

1st: __________ (CaCO₃)- 1/3%

2nd: _________ (CaSO₄•2H₂O)- 3 1/2 %

3rd: _________ (NaCl) -78%

4th: __________ (KCl& MgCl) - 11%

5th: _________ (NaNO₃)- trace

What is the “Bullseye” model of evaporates?

Map of all U.S. Evaporite Deposits

Where would you go to look for Potassium deposits?

Where would you go to look for Nitrate deposits?

Where would you go to look for Phosphate deposits?

Successive stages in forming coal (figure 7.16)

How do you make Coal?

1) High rate of __________________ (mainly land plants)

2) Preserved in a ________________ environment

3) Burial / compaction

Map of U.S. Coal Fields

Q. Where does Houston get its Coal?

A.

How do you make Oil?

1) High rate of biological productivity (mainly marine micro-organisms)

2) Preserved in a reducing environment

3) Burial /compaction/maturation

4) Migration through a permeable rock

5) Trapping by an impermeable seal

Types of Oil Traps