An Introduction to Geology

1
An Introduction to Geology
Sedimentary Rocks
2
Back to the Rock Cycle
3
Sedimentary processes
OF

• 1. Weathering
• 2. Transportation
• 3. Deposition
• 4. Lithification

A. Existing rocks B. Biological materials C.
Chemical precipitates
4
Sedimentary processes
5
Common sedimentary minerals
Feldspars

• Quartz

Micas
Calcite
6
Hand specimens

• First impressions?

7
Weathering
Physical / Mechanical
8
Weathering
Chemical / Biological
9
Weathering clasts
10
Transportation
11
Transport mechanisms
Rivers fluvial
Seas marine
Mississippi delta
12
Transport mechanisms
13
Transportation
Proximity velocity grain size
14
Transport time maturity
Textural maturity
15
Transport time maturity
Mineralogical maturity
16
Deposition

• Transportation into basins

17
Lithification
Deposition ( deposition deposition)
burial Burial compaction cementation
18
Compaction
Stylolites in chalk
19
Cementation

• Mineral precipitation into pore spaces
• e.g. calcite, quartz, haematite

20
Hand specimens

• Second impressions?

21
Sedimentary rocks
Particle size, shape and composition
Grain size Classification Example
gt2 mm Rudaceous Conglomerate



22
Conglomerate
23
Sedimentary rocks
Particle size, shape and composition
Grain size Classification Example
gt2 mm Rudaceous Conglomerate
0.06-2 mm Arenaceous Sandstone


24
Sandstone
25
Sedimentary rocks
Particle size, shape and composition
Grain size Classification Example
gt2 mm Rudaceous Conglomerate
0.06-2 mm Arenaceous Sandstone
0.004-0.06 mm Argillaceous Siltstone

26
Siltstone
27
Sedimentary rocks
Particle size, shape and composition
Grain size Classification Example
gt2 mm Rudaceous Conglomerate
0.06-2 mm Arenaceous Sandstone
0.004-0.06 mm Argillaceous Siltstone
lt0.004 mm Argillaceous Claystone
28
Claystone
Bituminous shales, Saltwick Nab, near Whtby
29
Sedimentary rock types

• 1. Clastic (or detrital)

30
Sedimentary rock types

• 1. Clastic (or detrital)

31
Sedimentary rock types

• 2. Biogenic (or organic)

32
Sedimentary rock types

• 2. Biogenic (or organic)

33
Sedimentary rock types

• 3. Chemical (precipitates)

34
Hand specimens

• What sedimentary rock type is your specimen?

35
Sedimentary structures
Bedding
36
Sedimentary structures
Cross-bedding
37
Sedimentary structures
Cross-bedding
38
Sedimentary structures
Ripple marks
39
Sedimentary structures
Mud cracks
40
Sedimentary structures

• Shell beds

41
Sedimentary structures
Trace fossils
42
Sedimentary UK
43
Next week

• Under Pressure

• Metamorphic Rocks