1. What Environment are Sedimentary Rocks Formed?

2. Types of Sedimentary Rocks
Introduction
Origin of sedimentary rocks
– Clastic Rocks
– Crystalline (Chemical) and Bioclastic Sedimentary Rocks
Interpreting Sedimentary Rocks
– Environment of deposition
– Sedimentary structures
What is a Sedimentary Basin?
– A thick accumulation of sediment
– Necessary conditions:
1. A depression (subsidence)
2. Sediment Supply

3. World Map of Sedimentary Rocks Basins

4. Planet Earth: Liquid Water and Plate Tectonics
SEDIMENTS
Unconsolidated products of Weathering & Erosion
– Loose sand, gravel, silt, mud, etc.
– Transported by rivers, wind, glaciers, currents, etc.
• Sedimentary Rock:
– Consolidated sediment
– Lithified sediment

5. Types of Sedimentary Rocks and Environment of Formation
Land Derived Materials Transported by a River
3 Basic Types of Sedimentary Rocks • Land Derived ( Clastic) – Made of Rock Fragments • Crystalline (Chemical) – Precipitated from Chemical Solution • Bioclastic – Formed by remains of plants and animals

6. Processes of formation
1. Weathering – mechanical & chemical 2. Transport – by river, wind, glacier, ocean, etc. 3. Deposition – in a point bar, moraine, beach, ocean basin,etc 4. Lithification – loose sediment turns to solid rock

7. Processes during Transport
• 1. Sorting – Grain size is related to energy of transport – Boulders high energy environment – Mud low energy

8. Stream Deposition Black shales → Source rocks Porous Sandstone
Significance for Petroleum System?
Black shales → Source rocks
Porous Sandstone

9. Processes during Transport
2. Rounding
– abrasion is progressive
– angular grains near source
– rounded grains long transport

10. Sorting and Rounding Bimodal rounding Poorly sorted Lithic sandstone
Well rounded
Well sorted
Quartz sandstone
Bimodal rounding
Poorly sorted
Lithic sandstone

11. Lithification • Decrease in pore space
• Compaction
• Decrease in pore space
• Due to increasing pressure with burial
• Cementation
• Pores filled
• quartz or calcite cements
• Recrystallization
• No porosity left
• Beginning of metamorphism

12. Lithification
Determines the nature of the reservoir • Critical for economic viability • Highly variable • Hard to predict ahead of the drill