Qbb 2023-clastic Sedimentology And Petrography-quiz

30 Questions | Total Attempts: 77

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Qbb 2023-clastic Sedimentology And Petrography-quiz - Quiz

Questions and Answers
  • 1. 
    At high wind velocities silt- and clay-sized particles are carried as bed load.
    • A. 

      True

    • B. 

      False

  • 2. 
    Grain roundness is therefore a characteristic that can easily be seen in hand specimen using a hand lens, or will be evident under the microscope if a thin-section is cut of an aeolian sandstone
    • A. 

      True

    • B. 

      False

  • 3. 
    Calcium carbonate (CaCO3) is the principal compound in limestones.
    • A. 

      True

    • B. 

      False

  • 4. 
    Cherts are fine-grained siliceous sedimentary rocks made up of silt-sized interlocking quartz crystals (microquartz) and chalcedony, a form of silica which is made up of radiating fibres a few tens to hundreds of microns long.
    • A. 

      True

    • B. 

      False

  • 5. 
    Sediments and sedimentary rocks with a high proportion of organic matter are termed carbonates because they are rich in carbon.
    • A. 

      True

    • B. 

      False

  • 6. 
    If all the clasts are of the same material (all of granite, for example), the conglomerate is considered to be polymict
    • A. 

      True

    • B. 

      False

  • 7. 
    Silt is a textural term to define the finest grade of clastic sedimentary particles, those less than 4 microns in diameter.
    • A. 

      True

    • B. 

      False

  • 8. 
    When clay- and silt-sized particles are mixed in unknown proportions as the main constituents in unconsolidated sediment we would call this material shale.
    • A. 

      True

    • B. 

      False

  • 9. 
    Feldspar is the most common mineral seen in silt deposits
    • A. 

      True

    • B. 

      False

  • 10. 
    Montmorillonite minerals can not absorb water within their structure.
    • A. 

      True

    • B. 

      False

  • 11. 
    A well sorted deposit contains a wide range of clast sizes.
    • A. 

      True

    • B. 

      False

  • 12. 
    Fabric- If a rock has a tendency to break in a certain direction, or shows a strong alignment of elongate clasts, this is described as the fabric of the rock.
    • A. 

      True

    • B. 

      False

  • 13. 
    Cement - Fine-grained material occurring between the sand grains
    • A. 

      True

    • B. 

      False

  • 14. 
    Shale refers to a rock formed from:
    • A. 

      Sand sized material

    • B. 

      Plant remains

    • C. 

      Clay minerals

    • D. 

       Carbonate

  • 15. 
    A clastic rock is:
    • A. 

      A rock formed from evaporation of sea water

    • B. 

      Transformed by heat into limestone

    • C. 

      A rock formed from the cementation of transported grains

    • D. 

      Transformed by pressure into limestone

  • 16. 
    Which one of the following features is NOT associated with sedimentary rocks?
    • A. 

      Bedding

    • B. 

      Foliation

    • C. 

      Fossils

    • D. 

      All may be associated with sedimentary rocks

  • 17. 
    Which of the following types of sediments are most abundant?
    • A. 

      Coarse clastics

    • B. 

      Fine clastics

    • C. 

      Chemical

    • D. 

      Biochemical

  • 18. 
    The tendency for variations in current velocity to segregate sediments on the basis of particle size is called _____.
    • A. 

      Dissolution

    • B. 

      Sorting

    • C. 

      Compaction

    • D. 

      Lithification

  • 19. 
    Which of the following types of currents can transport sand grains?
    • A. 

      Rivers

    • B. 

      Ocean waves

    • C. 

      Wind

    • D. 

      All above

  • 20. 
    Which of the following processes is not an important cause of subsidence during the development of a sedimentary basin?
    • A. 

      Deposition of sediments

    • B. 

      Cooling and contraction of the crust

    • C. 

      Tectonic down faulting

    • D. 

      Erosion of sediments

  • 21. 
    Mudrocks that contain a high proportion of organic material that can be driven off as a liquid or gas by heating are called oil shales.
    • A. 

      True

    • B. 

      False

  • 22. 
    The presence of the oil in the pores of the sediment prevents the formation of any cement, so tar sands remain lithified, held together only by the bitumen that gives them a black or very dark brown colour.
    • A. 

      True

    • B. 

      False

  • 23. 
    If over one-thirds of a rock is solid organic matter it may be called a coal
    • A. 

      True

    • B. 

      False

  • 24. 
    Evaporite - These are minerals formed by precipitation out of solution as ions become more concentrated when water evaporates.
    • A. 

      True

    • B. 

      False

  • 25. 
    Authigenic minerals - Minerals that grow as crystals in a depositional environment are called authigenic minerals.
    • A. 

      True

    • B. 

      False

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