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Geology · 300 Level
This is the complete lecture note for GEY 314 Sedimentary Petrology, prepared for Geology students at 300 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS GEY 314: Sedimentary Petrology (3 Units C: LH 30; PH 45) Course Code: GEY 314 Course Title: Sedimentary Petrology Course Unit: 3 Units C Series 1: Types, Sources, And Transportation Of Sediments Series 2: Deposition, Diagenesis, And Lithification Series 3: Grain Size Analysis, Textures, And Structures Of Sedimentary Rocks Series 4: Mineral Composition, Petrographic Classification, And Heavy Minerals Series 5: Provenance Studies Of Ancient Sediments Series 1: Types, Sources, And Transportation Of Sediments • Part 1.1 Types Of Sediments • 1.1.1 Clastic sediments • 1.1.2 Chemical sediments • 1.1.3 Biogenic sediments • Part 1.2 Sources Of Sediments • 1.2.1 Weathering processes • 1.2.2 Erosion and sediment supply • Part 1.3 Agents Of Sediment Transportation • 1.3.1 Water as a transporting agent • 1.3.2 Wind, ice, and gravity • Part 1.4 Transportation Mechanisms Of Sediments • 1.4.1 Traction and saltation • 1.4.2 Suspension and solution
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Sediments are the raw materials from which sedimentary rocks are formed, and their study provides vital clues about Earth’s history and processes. Every grain of sand or fragment of clay carries evidence of its origin, journey, and eventual deposition. By examining the types, sources, and movement of sediments, geologists can reconstruct past environments and better understand the processes shaping our planet. The aim of this Series is to introduce you to the different types of sediments, their sources, and the agents and mechanisms by which they are transported. This foundation is essential for progressing into more advanced aspects of sedimentary petrology. We shall commence this Series by exploring the types of sediments, including clastic, chemical, and biogenic forms. Next, we will examine the sources of sediments, focusing on weathering and erosion. Following that, we will consider the agents of sediment transportation such as water, wind, ice, and gravity. Finally, we will wrap up by studying the specific mechanisms of transportation, including traction, saltation, suspension, and solution. Series Learning Outcomes (SLOs) for Series 1: Types, Sources, And Transportation Of Sediments Upon completing this Series, you should be able to: • SLO 1.1 define and differentiate the main types of sediments, including clastic, chemical, and biogenic forms. • SLO 1.2 explain the sources of sediments, focusing on weathering processes and erosion. • SLO 1.3 describe the agents of sediment transportation such as water, wind, ice, and gravity. • SLO 1.4 analyse the mechanisms of sediment transportation, including traction, saltation, suspension, and solution. 1.1 Types Of Sediments 1.1.1 Clastic sediments Clastic sediments are fragments of pre-existing rocks that have been broken down through physical and chemical weathering. They range in size from large boulders to fine clay particles. These sediments are transported by agents such as water, wind, or ice before being deposited in various environments. Clastic sediments are classified according to grain size, shape, and sorting. For example, sandstones are composed mainly of sand-sized particles, while shales consist of fine clay and silt.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The study of clastic sediments helps geologists reconstruct past environments and understand the processes that shaped them. Short description: Diagram showing different sizes of clastic sediments from boulders to clay. Caption: Figure 1.1 Classification of clastic sediments by grain size Fill in the blank: Clastic sediments are fragments of ______ rocks broken down by weathering. 1.1.2 Chemical sediments Chemical sediments form when dissolved minerals precipitate directly from water. This process often occurs in lakes, seas, or evaporating basins where mineral saturation leads to deposition. Common examples include limestone, formed from calcium carbonate, and evaporites such as gypsum and halite. These sediments provide important clues about past chemical conditions of depositional environments. For instance, thick beds of evaporites indicate arid climates with high evaporation rates.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Short description: Image of gypsum and halite as examples of chemical sediments. Caption: Plate 1.2 Examples of chemical sediments: gypsum and halite Fill in the blank: Limestone is a chemical sediment formed from ______ carbonate. 1.1.3 Biogenic sediments Biogenic sediments are derived from the remains of living organisms. They include shells, corals, plant material, and microscopic organisms such as diatoms. When these accumulate, they form rocks like coal, chalk, or bioclastic limestone. Biogenic sediments are particularly important for interpreting past biological activity and environmental conditions. For example, chalk deposits indicate the accumulation of microscopic marine organisms in ancient seas. Box 1.3 Examples of biogenic sediments and their resulting rocks Biological Source Primary Component Resulting Rock Type Typical Environment Marine Shells/Corals Calcium Carbonate ($CaCO_3$) Limestone Warm, shallow tropical seas Microscopic Algae Calcareous Nanofossils Chalk Deep ocean basins
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Biological Source Primary Component Resulting Rock Type Typical Environment Woody Plant Matter Organic Carbon Coal Tropical or temperate swamps Diatoms/Radiolaria Silica ($SiO_2$) Chert / Diatomite Cold or nutrient-rich deep water Bone/Guano/Fish Scales Calcium Phosphate Phosphorite Areas of high ocean upwelling Fill in the blank: Chalk is formed from the accumulation of microscopic ______ organisms. Pilot questions 1.1 1. What are clastic sediments? 2. Give two examples of chemical sediments. 3. Which rock is formed from plant material accumulation? 4. What type of sediment is chalk derived from? 5. Why are biogenic sediments important in geological interpretation? 1.2 Sources Of Sediments 1.2.1 Weathering processes Weathering refers to the breakdown of rocks at or near the Earth’s surface through physical, chemical, or biological means. Physical weathering involves mechanical processes such as freeze-thaw action, exfoliation, or abrasion, which break rocks into smaller fragments without altering their composition. Chemical weathering occurs when minerals react with water, oxygen, or acids, leading to changes in composition, such as the transformation of feldspar into clay. Biological weathering results from the activity of plants, animals, and microorganisms, for example, roots penetrating cracks in rocks. Weathering is the primary source of sediments, as it produces the particles that are later transported and deposited. Short description: Diagram showing physical, chemical, and biological weathering processes.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Caption: Figure 1.4 Weathering processes as sources of sediments Fill in the blank: The transformation of feldspar into clay is an example of ______ weathering. 1.2.2 Erosion and sediment supply Erosion is the removal and movement of weathered material by agents such as water, wind, ice, or gravity. Unlike weathering, which produces sediments, erosion transports them away from their source. The rate of erosion depends on factors such as climate, vegetation cover, and rock type. Sediment supply refers to the amount and type of material available for transport. Regions with high rainfall and steep slopes often have abundant sediment supply, while arid regions may produce finer particles through wind erosion. Understanding erosion and sediment supply is crucial for predicting depositional environments and sedimentary rock formation. Box 1.5 Factors influencing erosion and sediment supply
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Factor High Erosion / High Supply Low Erosion / Low Supply Climate Tropical (High rain) or Alpine (Freeze-thaw) Arid (Low rain) or Temperate (Consistent) Vegetation Sparse (Desert, Deforested, or Tundra) Dense (Rainforest, Grasslands) Topography Steep slopes, High relief (Mountains) Flat plains, Low relief (Plateaus) Lithology Soft/Fissile (Shale, Mudstone, Ash) Hard/Crystalline (Granite, Quartzite) Human Impact Urbanization, Mining, Intensive Farming Reforestation, Terracing, Conservation Fill in the blank: Unlike weathering, erosion is responsible for the ______ of sediments from their source. Pilot questions 1.2 1. What is weathering? 2. Name two types of chemical weathering. 3. How does biological weathering occur? 4. Define erosion in relation to sediments. 5. Mention two factors that influence sediment supply. 1.3 Agents Of Sediment Transportation 1.3.1 Water as a transporting agent Water is the most significant agent of sediment transportation. Rivers, streams, and ocean currents move sediments of varying sizes depending on their velocity and energy. Fast-flowing rivers can carry large boulders and pebbles, while slower currents transport finer materials such as silt and clay. Transportation by water often results in well-sorted sediments, as particles are separated according to size and density. Rounded grains are also common because continuous movement causes abrasion.
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