Questions and Answers
In Dunham's classification, the sediment is called a grainstone if the grains of a limestone are touching one another and the sediment contains no mud.
True
A packstone is a carbonate sediment that is grain supported and contains a small percentage of mud.
True
A wackestone is a mud supported sediment that contains more than 10 percent grains.
True
A mudstone is a sediment that is mud supported and contains less than 10 percent grains.
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Boundstone is a type of biogenic reef rock.
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Which grain size classification is used for limestone according to Grabau (1903)?
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What is the main criteria for classifying limestones according to Folk?
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What are the two main groups of "allochemical Rocks" in Folk's classification?
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What is the size range of micrite in microcrystalline allochemical limestone?
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How are the "allochemical Rocks" further subdivided in Folk's classification?
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Study Notes
Dunham's Classification of Limestones
- Grainstone: Limestone where grains touch each other without any mud content.
- Packstone: Carbonate sediment that is grain-supported and has a small amount of mud.
- Wackestone: Mud-supported sediment containing more than 10% grains.
- Mudstone: Mud-supported sediment with less than 10% grains.
- Boundstone: Biogenic reef rock type that includes cemented sediments from biological activity.
Grain Size Classification
- Grabau (1903): Introduced a classification system for limestone based on grain size.
Classification Criteria according to Folk
- The primary criterion for classifying limestones involves the relative amounts of grains and matrix.
Allochemical Rocks in Folk's Classification
- Two main groups of allochemical rocks include grains (such as ooliths and peloids) and cement.
Micrite Size Range
- Micrite in microcrystalline allochemical limestone typically falls within a specific grain size range, measured in micrometers.
Subdivision of Allochemical Rocks
- Allochemical rocks are subdivided further based on the composition and size of their constituents, which can include various types of grains and matrix materials.
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Description
Test your knowledge of Dunham's classification for rock descriptions with this quiz! Learn about the different depositional textures and how they can be observed using a hand lens or binocular microscope. Explore examples of grainstones, packstones, and more. Perfect for geology enthusiasts and students!
