GL101 Lecture 5: Chapter 6
Chapter 6 - Sedimentary Rocks
What is a Sedimentary Rock
• Products of mechanical and chemical weathering
• About 5% (by volume) of Earth’s outer 16km
• Evidence of past environments
• Info about sediment transport
• Commonly contain fossils
• Economically:
• Coal
• Petroleum and natural gas
• Iron, aluminum, manganese, fertilizer, raw materials for construction
Sediment into Sedimentary Rock: Diagenesis and Lithification
• Diagenesis
• All changes after sediments are deposited but prior to metamorphism
• Upper few km of Earth’s crust generally <200°C
• Includes:
• Re-crystallization – development of more stable minerals from less stable ones
• Lithification – unconsolidated sediments transformed into solid sedimentary rock by
compaction and cementation
• Natural cements: calcite, silica, and iron oxide
Sedimentary Environments
• Geographic setting and environmental conditions determine nature of sediment that accumulates
(grain size, grain shape, colour, etc.)
• Uniformitarianism – study presents environments and observe (and interpret) the same features in
ancient rocks
• Types of Sedimentary environments:
1. Continental
2. Transitional
3. Marine
• Continental
• Erosion and deposition (streams)
• Cold: glaciers move large volumes and sizes of sediment
• Aeolian (wind) deposits are well-sorted
• Transitional (shoreline)
• Quiet: may form tidal flats
• Higher energy: beaches, spits, bars, barrier islands
