Sedimentary Structures Flashcards
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Sedimentary Structures Flashcards

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Questions and Answers

What is a Sedimentary Structure?

The way grains are organized in the rock.

What do bedding concepts imply about sedimentary beds?

  • All sedimentary beds are deposited horizontally. (correct)
  • All sedimentary beds are deposited vertically.
  • Younger rocks are always on the bottom.
  • 'Up' points to younger rocks. (correct)
  • What is a Graded Bed?

    Starts with big cobbles and moves up to small pieces with high energy, often caused by floods.

    What causes Cross Beds?

    <p>Wind erosion creating dunes.</p> Signup and view all the answers

    What are Ripples?

    <p>Beach area with shallow water moving back and forth.</p> Signup and view all the answers

    What are Mudcracks?

    <p>Preserved in the rock from ancient to current.</p> Signup and view all the answers

    What does Sedimentary Provenance refer to?

    <p>Where sedimentary rock comes from.</p> Signup and view all the answers

    Which of the following describe Sandstone Provenance?

    <p>All of the above.</p> Signup and view all the answers

    What are Chemical Sedimentary Rocks: Inorganic Precipitates?

    <p>Precipitates from solution form sedimentary beds, including evaporites.</p> Signup and view all the answers

    What do Chemical Sedimentary Rocks: Organics entail?

    <p>Reefs form from limestone in deep water environments from calcium and carbonate from dead sea life.</p> Signup and view all the answers

    What is the Source of Oil?

    <p>Made from innards and guts of diatoms and radiolarians (plankton).</p> Signup and view all the answers

    What is the Source of Coal?

    <p>Found in a swamp, from dead plant debris.</p> Signup and view all the answers

    What does Compaction in Sedimentary Lithification refer to?

    <p>Layers pile up, bottom layer gets squished, space between grains decreases.</p> Signup and view all the answers

    What is Cementation in Sedimentary Lithification?

    <p>Water flows in between grains and ions create precipitates which hold grains together.</p> Signup and view all the answers

    Which environments are classified under Sedimentary Depositional Environment: Fluvial?

    <p>River environment.</p> Signup and view all the answers

    What is characterized as Sedimentary Depositional Environment: Deep Marine?

    <p>Mudstone, Chert.</p> Signup and view all the answers

    In which environment would you find Sedimentary Depositional Environment: Shallow Marine?

    <p>Beach.</p> Signup and view all the answers

    What does Sedimentary Basins and Tectonics imply?

    <p>Sinking layers with layers deposited at the same elevation.</p> Signup and view all the answers

    What is a Rift Basin?

    <p>Crust spreads, thins, and sinks.</p> Signup and view all the answers

    What characterizes a Flexural Basin?

    <p>Crust flexes downwards, making space for sediments.</p> Signup and view all the answers

    Study Notes

    Sedimentary Structures

    • Grains in rocks are organized in specific patterns, defining sedimentary structures.
    • Bedding refers to sedimentary beds that are deposited horizontally, with "up" indicating younger rock layers.

    Key Sedimentary Features

    • Graded Bed: Characterized by larger cobbles at the bottom and smaller grains at the top, often formed by flood events.
    • Cross Beds: Result from wind erosion creating dunes; the direction of wind or dune formation is indicated as "up."
    • Ripples: Formed in shallow beach water where waves cause sediment movement.

    Environmental Indicators

    • Mudcracks: Indications of drying conditions, preserved in the rock throughout geological history.
    • Sedimentary Provenance: Describes the origin of sedimentary rocks and their source materials.

    Sandstone Types

    • Arenite: Composed predominantly of quartz, formed far from mountains but close to coastal regions.
    • Arkose: Contains significant potassium feldspar, formed near coastal regions.
    • Graywacke: Located close to mountains, this rock includes quartz, feldspar, and rock fragments.

    Chemical Sedimentary Rocks

    • Inorganic Precipitates: Formed when minerals precipitate from solution, leading to sedimentary beds; evaporites are specific deposits resulting from evaporation in lake basins.
    • Organics: Reefs develop from limestone in deep water, as calcium carbonate is produced from the skeletal remains of marine life.

    Sources of Energy Resources

    • Oil is generated from the remains of diatoms and radiolarians, both types of plankton.
    • Coal originates from decayed plant debris found in swamp-like environments.

    Lithification Processes

    • Compaction: Occurs as layers accumulate, causing the bottom layer to compress, which reduces the spaces between grains.
    • Cementation: Involves the flow of water between grains, where ions precipitate to bond grains together.

    Depositional Environments

    • Fluvial: Environments related to rivers, resulting in conglomerate, sandstone, mudstone, and coal formations in floodplain and swamp areas.
    • Deep Marine: Found in deep ocean settings, characterized by deposits like mudstone and chert from dead phytoplankton.
    • Shallow Marine: Consists of environments such as beaches, lagoons, and reefs.

    Sedimentary Basins and Tectonics

    • Sedimentary basins form from the sinking of crust layers, with deposits maintaining consistent elevation.
    • Rift Basin: Created when the crust stretches, thins, and sinks.
    • Flexural Basin: Formed by downward flexing of the crust, allowing for sediment accumulation; often associated with mountain building.

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    Description

    Test your knowledge of sedimentary structures with these flashcards. Each card presents a term related to sedimentary geology, along with its definition, helping you understand the organization of grains in rocks and related concepts. Perfect for geology students looking to enhance their vocabulary and insights into sedimentary processes.

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