EOS 201 MT

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EOS 201 MT
2014-02-24 02:19:01
EOS 201 MT
EOS 201 MT
EOS 201 MT
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  1. What is sedimentology vs sedimentary petrology
    sedimentology: processes that erode, transport, and deposit sediments

    petrology: charectoristics and origins of sed rocks

    • sedimentology=process
    • petrology=products
  2. what is a facies
    facies refers to spefic charectoristics of a rock as a product of its depositional enviornment
  3. which dep enviorn has the best preservation, Why?
    Deep ocean basins, due to the low oxygen content and low energy.

    anything above sea level is being eroded and moved to below sea level.
  4. what is the principle of Uniformitarianism?
    that the processes that have shaped earth in th epast will exist in the future thus we can use events in the past to predict the future.
  5. Physical weathering products & effects & name (4) types
    effect of amalgamated physical weathering is that it increases the surface area of existing rock.

    Products: clasts and matrix material

    • +freeze thaw (water vol inc/dec)
    • +insolation (thermal exp/dec)
    • +orogenic or glacial rebound
    • +organic activity (roots/burrows)
  6. Biological weathering
    from organisms, works as both chemical and physical weathering
  7. Chemical weathering products, effects and (4) types
    • effect: breakdown into alteration materials
    • product: cements

    • Dissolution (cal, hal)
    • oxidation (olv, pyx)
    • hydrolosis (silicates)
    • hydration/dehydration (anhydrite, gyp)
  8. What does the following describe

    CaCO3 + H2CO3--->Ca2++ 2H2O
    A dissolution reaction (new ions in solution in products)

    this particular rxn is the dissolution of calcium carbonate with carbonic acid to produce calcium ions in solution
  9. what does the following describe?

    (Fe2+)2SiO6 + O2 + H2O -> 4Fe3+(OH)3 + H4SiO4
    A oxidation or redux reaction (notice how the oxydation number of Fe has changed)

    specifically this reaction is the oxidation of pyroxene  to limonite
  10. what does the following describe?

    CaSO4·2H2O <-->CaSO4(s) + H2O(l)
    This is a hydration/dehydration (the forward is dehydration) Note the solid product with water a s a by product

    this specific rxn is that of anyhrite dehydration to gypsum
  11. what does the following describe

    KAlSi3O8 + H+-->Al2Si2O5(OH)4 + K+ +H4SiO4
    This is a hydrolysis reaxtion not the H+ in the reactants side of the rxn

    this specific rxn is feldspare to kaolinite with k ions in sol and silic acid as by product
  12. generally rock fragments (clasts) such as qtz & musk are products of
    physical weathering
  13. generally clay minerals such as illite, kaolinite are products of
    they are hydrous aluminum phyllosillicates which are the proucts of 

    Hydrolosis reaxiotns
  14. evaporites such as gypsum, halite, calcite, carbonate anre products of?
    these are all products of precipitations from dissolution rxns
  15. why is there a salinity difference between fresh and marine water?
    because of the transport in fresh and the holding tank that is marine. all due to residency times and and solubility
  16. what is the corelation between solubility and evaporation
    High solubility=low evaportaion


    calcium precips before gypsum then halite

    ∴halite is at the center of a closed basin and the landward edge of a restricted basin
  17. which chemical weathering depends on rain? which doesent?
    oxidation does not dpepend on rain, in diffrent ways you could argue the others, hydration, dissolution hydrolosis
  18. what type of soil will limestone make?
    trick question, it will make ions in solution not soil
  19. describe weathering in the artic
    mostly physical (although lichens do play a bio and chem role) 

    primarily freeze thaw lithic frags
  20. describe desert weathering
    primarily physical due to insolation flds may be present as lithics as no water for ions in sol.

    oxidation makes iron oxides

    fine sediment may bel blow all the way around the world
  21. describe temperate weathering
    includes all types and proccesses, typically a lot of lithics, larger grain saize a younger soil
  22. describe tropical weathring
    includes all types but chemical weathering is highest due to high Temp making rxns faster/easier.

    lots of thick clays (think jungle quicksand) lots of hematite and kaolinite
  23. extrabasinal or siliclastic rock types
    • clast framework differs from matrix
    • clast and 2ndry provenace is outside of depositionl basin 

    seds typ: qtz,flds,msk,clays, Fe3+

    • conglomerates>2mm
    • sandstones 2-1/16thmm
    • mudstone < 1/16thmm
    •      *siltstone=gritty
    •      * claystone=smoth
  24. Intrabasinal rock types
    originate within the depositional basin  from dissolved constituients

    chemical-evaporites and Iron formations

    biochem/biogen/organic- carbonates, cherts, phosphates, carbonacious
  25. bimodal-unimodal-polymodal
    refers to the the grains size of a sample

    • unimodal-one size typical of delta or deep sea
    • bimodal- 2 sizes- typical of river
    • polymodal- several sizes typical of glacier
  26. what are allochems (2 specific names)
    carbonate (limestone) grains that form intrabasinally

    • peloids- poop
    • ooids- coated grains (skelatal or lithic)
  27. what is spar
    coarse crystaline cement that fills the pore spaces of carbonate rocks
  28. what is micrite?
    carbonate mud acts as a cement in carbonate rocks

    can begin to crystalize at which point it is called micro-spar

    (spar is the crystal)
  29. black shales are typical of what type of sed rock
    black shales are often common of phospherites

    the black coming from the high amount of organic rich undecayed carbon material they posses
  30. whare are humic materials what is significant about them?
    Humic materials are those derived from plants, they are a major source of carbon in sed rocks

    primarily humic materials are responsible for coal deposits
  31. what are sapropelic materials

    when where/are they most common?
    sapropelic materials are decomposed marine organisms (phyto/zoo plankton) they are major contributors to oil resivors anre are what commonloy give phospherites their dark-black color

    most common during anoxic (without oxygen) periods in earth history due to high levels of CO2
  32. what are the 4 types of coal from least to most Carbon content
    • peat
    • lignite
    • bitumasious coal
    • anthracticite
  33. what is karogen?
    another name for oil shale. kerogen bearing mudstones have ~25% carbon matter.

    kerogen is microbially altered plant and animal mater
  34. what is the relationship between kerogen and petroleum?
    petroleum is the end product that is derived through the maturation of kerogen to hydrocarbon polymers
  35. bifs
    the older of the two iron rich ssed rocks

    laminations a/o beeding of iron rich material (hematite magnetite) between marine muds/shales/cherts
  36. ironstones
    phanerozoic iron stones newer then bifs

    not laminated/intrabedded the way BiFS are

    from errosion of latericit (fe or al rich) soil
  37. two main ways rocks are transported
    1- intrabasinally as ions in solution producing crystaline chem or biochem rock

    2- extrabasinaly as clasts produce clastic sed rocks
  38. what are the three forces related to sediment transport and how do they effect transport
    • FG-gravity- holds grain to btm
    • FD-drag force or shear force
    • FL-Lift force- Bernoulli effect

    • FG>FD+FL sed remains on bed or settles out
    • FG<FD+FL sed will be entrained in current
  39. what is the bernoulli effect?
    basically as current velocity changes above and below a sediment an area of low pressure above and downstream of a sediment which helps it to become entrained in the current flow
  40. what is a hjulstrom cruve
    a graph showing the relationship between stream velocity and the ability to entrain varrying sized sediments
  41. what are the two chars of fluid transport
    • 1- reynolds number
    • 2- froudes number
  42. what is Reynolds number
    ratio of inertia to viscosity

    determines whether a flow is laminated or turbulent

    • reynolds low= laminar
    • reynolds high= turbulent
  43. laminar flow vs turbulent flow
    laminar is smooth, sub parellel sheets flowing slowly, mostly viscous fluids

    turbulent is rough, irregular flow, eddies, lower viscosity fluids
  44. what is froudes number

    what are the difrences in structure created by the high or low number
    ratio of inertia to gravity

    fr<1=tranquil flow, small quantity sediment transport. ripples, sandwaves and dunes

    fr>1= rapid flow, large quantity sediment transported, plane beds, antidunes, chutes and pools
  45. what is bedload transport
    sediment moves along bedding surfaces through

    traction- rolling sliding creeping

    slatation- intermittent contact with the bed due to eddies...think of it bouncing down the bed form
  46. what is suspended load transport
    when sediment is entrianed in the current flow

    usually smaller grains

    turbulence is needed to keep grains entrained
  47. unidirectional flow FR<1 means what?
    water surface?quantity of sed transported?
    • Fr<1= lower flow regime
    • irregular water surface
    • small sed transport

    creates ripples sandwaves and dunes
  48. unidirectional flow FR>1 means what?bedforms?water surface?quantity of sed transported?
    Fr>1= upper flow regime

    • glassy streaked out water
    • large quantity of sed transport

    creates plane beds, antidunes, chutes and pools
  49. more simply put what is the diffrence between reynold and fruede number telling us
    reynolds number tells us the type of flow laminar or turbulent

    frueds tells us bedforms (low fr= ripples, dunes, sandwaves...hig= planebeds, antidunes chutes and poools
  50. what is the angle of cross bedding in air compared to water

    cross bedding refers to what side of a dune/ripple
    water tends to have a much shalllower x-beeding in the area of 15°

    air tends to be steepper around 30°

    x bedding will be indicitive of the lee (steeper)side ∴ the cross bedding tends to dip in the dirrection of flow
  51. how can we tell orientation from cross bedding?
    cross bedding is indicitive of the lee (stepper side) of the dune/ripple there for it basicly will appear to dip down stream

    cross beding will have a ntangential base which tells us which is the top/btm side of the bed
  52. how is hearing bone cross startification diffrent then cross stratification
    cross stratification is created by asymetrical ripples showing unidirectional motion, thus the lee side of the ripples is presserved in a parrellel planar fashion

    hearing bone is from bi directional symetrical ripples/dunes
  53. typicaly marine is a bidircetional flow which creates symetric features.

    What are the asymetiric marine features
    lenticular, wavy and flaser beding strucutres

    appear as wavy lines of mud inbetween beeding lenticular is thickes flaser thinest

    created from tidal currents where there is more force in one direction
  54. what is hummoky cross stratafication
    it is a product of ocean storm systmes

    hummocks are the high swales are the low
  55. what are the 3 dry components of gravity driven transport
    • 1- rockfall (rock must go through the air)
    • 2-rockslide
    • 3-slump

    these have little internal deformation of the material
  56. what are the 4 wet types of gravity driven transport
    • 1- grain flow
    • 2- debris flow
    • 3-turbidity current
    • 4- fluidised flow
  57. key points of grain flows
    • slope > 30°
    •  support by grain interactions= dispersive pressure
    • typical of aeolian sand slidding down face of dune
  58. key points of a fluidised flow
    • same thing as liquifaction
    • support by rising fluid through medium
    • can flow on slope of 3°
  59. key points of debris flow
    • support by cohesive mud matrix
    • slope ~10°
    • huge variation in grain size

    think of lahahrs volcanic mudflow
  60. key points of turbidity currents
    turbulence is the grain support mechanism

    like an underwater debris flow but more fluid = higher reynolds number
  61. what is the bouma series
    its a series of layers a-e (e on top) as the result of a turbidy current loosing its velocity

    •                   low velocity
    • E- fine mud with possible bioturbation (often not preserved)
    • D- suspension settling of fine material may display lenticular to flaser laminations
    • C- low flow regime seetling indicated by ripples a/o climbing ripples
    • B- high flow regime planar beddng of coarser material
    • A- more massive bed of coarsest sediments
    •                 highest velocity
  62. what is a flame structure
    a feature on the btm side of bedding where a more dense material has overrode a lighter matierial. the lighter material is pulled up into the upper layer
  63. what is a load cast
    when a suspended sediment is pulled downward by gravity into the underlying still soft bed.
  64. ball and pillow structures
    liquifaction of a less dense layer below a more dense layer allows the more dense amterial to be completyl pulled into it or something like that
  65. what is an ichnofacies

    what are the 4 types
    trace fossils...fossils of marine organism tracks that help to determine things like water temp, depth salinity etc.

    • 1-skolith-vertical tubes burrows
    • 2-cruziana- horizontal u shaped troughs
    • 3-zoophycos-arcuarate(bow shaped) feeding traces
    • 4-nereites-meandering feading trials
  66. what is diagenisis?
    al lthe changes that occur after deposition that turn it into a sed rock

    maybe biological, physical or chemical
  67. Physical Diagenisis
    creates tighter grain packing thus a reduction in porosity

    mud compacts the most 70% porosity to 20%
  68. biological diagenisis
    deals with the bioturbation and microbal activity. typically effeyts sediment size and chemistry of pore fluids.

    helps to create kerogen and thus HC resivoirs
  69. what are the 5 components of chemical diagenisis
    • 1-cementation
    • 2-authigenisis
    • 3-replacemet
    • 4-recrystilization
    • 5- dissoulution
  70. what is a stylotite
    serrated surfaces where mineral material has been removed by pressure dissolution
  71. name/describe 4 diagenitic structures
    • 1-liesegangen bands (rings of alterations material)
    • 2-concretions or nodules (hard percipates of mineral cement)
    • 3- sand xstals (large diagenitc calcite xstals)
    • 4-geodes- void in rock with diagentic minerals growing in it
  72. what is the typical vertical profile of an alluvial fan?
    It coarsens upwards
  73. After biological and physical diagfenisis do you have lithification?
    no you still need something to bind the rock we need chemical diagenisis
  74. 2 points about diagenic cementation
    turns the sediments into rock by binding the partilcles i.e. LITHIFASACTION

    cement fills almost all reming pore space significantly reducing porosity
  75. common cements in sandstone are?
    calcite and qtz, and iron oxide (1-2% will make it red)
  76. common carbonate cements?
    calcite, aragonite and dolomite
  77. cement textures for sandstones
    for carbonates
    • sandstone 
    • mosiac- between clasts
    • overgrowths- around clasts

    • cabonates
    • drusy
    • blocky
    • rimcement
  78. what is authigenis and examples of three commons
    authigenisis is the creations of new minerals in-situ

    • 1- clay minerals kaolonite to illite or chlorite
    • 2-feldspar-->clay--> sericite
    • 3- hematite and pyrite from fe bearing
  79. what is replacement diagenisis
    • chemical diagenisis refering to the replacement of one mineral to another 
    • for example petrifid wood all organic carbon is replaced by chert
  80. what is recrystalization diagenisis
    existing clasts retain their chemistry but grain size gets larger

    such as micrite turing in into spar
  81. what is dissolution in diagenisis?
    important process tha tincrease 2nd degree porosity in rocks by removing solubale minerals
  82. difference between bars in braided and meandering systmes
    • braided have tranverse and longitudal bars
    • tranverse-sndier cross bedded
    • longitudal- massive planar bed forms, imbricated pebbles x bedding at down stream side

    meandering have point bars- epsilon cross bedding from the lateral movement of the point bar and cut bank
  83. 6 points to recognizing fluvial deposits in the stratigraphic record
    • 1- total lack of absence of MARINE fosils
    • 2-relitivly poor sorting
    • 3- red color common of oxidation
    • 4- unidirectional patterns
    • 5- downstream decrease in grain size
    • 6- fining upwards

    easy to mistake with glacial outwash and delta plain deposits
  84. where is an envoirnment where you would expect to see fining up ward and coarsening upward
    finning upward at a point bar or delta

    coarsening upward in aluvial fans and progradtions
  85. would an aeolian enviornment be compositionaly mature or imature?
    imature, compositionaly mature is an extremly high level of only qtz. in aeolian there is still abundant feld and others that have not been removed due to the lack of water
  86. aeolian deposit charectoeristics
    • high angle 30deg (compared to 10-15 in water)
    • thick tabular cross bedding
    • no typical vertical sequencing
    • rare fossils